ALBERT

Description: This paper aims to propose monthly models responsible for the theoretical evaluation of the global horizontal irradiance of a tropical region in India which is Sivagangai situated in Tamilnadu. The actual measured global horizontal irradiance hails from a 5MW solar power plant station located at Sivagangai in Tamilnadu. The data were monitored from May 2011 to April 2013. The theoretical assessment was conducted differently by employing a programming platform called Microsoft Visual Basic 2010 Express. A graphical user interface was created using Visual Basic 2010 Express, which provided the evaluation of empirical parameters for model formulation such as daily sunshine duration ( S ), maximum possible sunshine hour duration ( S 0 ), extra terrestrial horizontal global irradiance ( H 0 ) and extra terrestrial direct normal irradiance ( G 0 ). The proposed regression models were validated by the significance of statistical indicators such as mean bias error, root mean square error and mean percentage error from the predicted and the actual values for the region considered. Comparison was made between the proposed monthly models and the existing normalized models for global horizontal irradiance evaluation.

Description: The ground-water heat-pump system (GWHP) provides a high efficient way for heating and cooling while consuming a little electrical energy. Due to the lack of scientific guidance for operating control strategy, the coefficient of performance (COP) of the system and units are still very low. In this paper, the running strategy of GWHP was studied. First, the groundwater thermal transfer calculation under slow heat transfixion and transient heat transfixion was established by calculating the heat transfer simulation software Flow Heat and using correction factor. Next, heating parameters were calculated based on the building heat load and the terminal equipment characteristic equation. Then, the energy consumption calculation model for units and pumps were established, based on which the optimization method and constraints were established. Finally, a field test on a GWHP system in Beijing was conducted and the model was applied. The new system operation optimization idea for taking every part of the GWHP into account that put forward in this paper has an important guiding significance to the actual operation of underground water source heat pump.

Description: This paper demonstrates the convergence of the integrated AC-DC power-flow algorithm as affected by the selection of different base values for the DC quantities and adoption of different control strategies for the DC link. For power-flow modeling of integrated AC-DC systems, the base values of the various DC quantities can be defined in several ways, giving rise to different sets of per-unit system equations. It is observed that different per-unit system models affect the convergence of the power-flow algorithm differently. In a similar manner, the control strategy adopted for the DC link also affects the powerflow convergence. The sequential method is used to solve the DC variables in the Newton Raphson (NR) power flow model, where AC and DC systems are solved separately and are coupled by injecting an equivalent amount of real and reactive power at the terminal AC buses. Now, for a majority of the possible control strategies, the equivalent real and reactive power injections at the concerned buses can be computed a-priori and are independent of the NR iterative loop. However, for a few of the control strategies, the equivalent reactive power injections cannot be computed a-priori and need to be computed in every NR iteration. This affects the performance of the iterative process. Two different per-unit system models and six typical control strategies are taken into consideration. This is validated by numerous case studies conducted on the IEEE 118-bus and 300-bus test systems.

Description: Combined cycle power plants (CCPPs) are in operation with diverse thermodynamic cycle configurations. Assortment of thermodynamic cycle for scrupulous locality is dependent on the type of fuel available and different utilities obtained from the plant. In the present paper, seven of the practically applicable configurations of CCPP are taken into consideration. Exergetic and energetic analysis of each component of the seven configurations is conducted with the help of computer programming tool, i.e., engineering equation solver (EES) at different pressure ratios. For Case 7, the effects of pressure ratio, turbine inlet temperature and ambient relative humidity on the first and second law is studied. The thermodynamics analysis indicates that the exergy destruction in various components of the combined cycle is significantly affected by the overall pressure ratio, turbine inlet temperature and pressure loss in air filter and less affected by the ambient relative humidity.

Description: In this paper, the choice of power quality compensator is a DSTATCOM which constitutes a three phase four leg voltage source converter (VSC) with a DC capacitor. The control strategy proposed for the DSTATCOM is a neural network based one cycle control (OCC). This control strategy involves neural network block, digital circuits and linear elements, which eliminates the sensors required for sensing the load current and coupling inductor current in addition to the multiplier employed in the conventional method. The calculation of harmonic and reactive currents for the reference current generation is also eliminated, thus minimizing the complexity in the control strategy. The control strategy mitigates harmonic/reactive currents, ensures balanced and sinusoidal source current from the supply mains that are nearly in phase with the supply voltage, compensates neutral current, and maintains voltage across the capacitor under unbalanced source and load conditions. The performance of the DSTATCOM with the proposed artificial neural network (ANN) controllers is validated and investigated through simulations using Matlab software. The simulation results prove the efficacy of the proposed neural network based control strategy under varying source and load conditions.

Description: Today, induction machines are playing, thanks to their robustness, an important role in world industries. Although they are quite reliable, they have become the target of various types of defects. Thus, for a long time, many research laboratories have been focusing their works on the theme of diagnosis in order to find the most efficient technique to predict a fault in an early stage and to avoid an unplanned stopping in the chain of production and costs ensuing. In this paper, an approach called Park’s vector product approach (PVPA) was proposed which was endowed with a dominant sensitivity in the case in which there would be rotor or stator faults. To show its high sensitivity, it was compared with the classical methods such as motor current signature analysis (MCSA) and techniques studied in recent publications such as motor square current signature analysis (MSCSA), Park’s vector square modulus (PVSM) and Park-Hilbert (P-H) (PVSM P-H ). The proposed technique was based on three main steps. First, the three-phase currents of the induction motor led to a Park’s vector. Secondly, the proposed PVPA was calculated to show the distinguishing spectral signatures of each default and specific frequencies. Finally, simulation and experimental results were presented to confirm the theoretical assumptions.

Description: The intend of this paper is to give a description of the realization of a low-cost wind turbine emulator (WTE) with open source technology from graze required for the condition monitoring to diagnose rotor and stator faults in a wind turbine generator (WTG). The WTE comprises of a 2.5 kW DC motor coupled with a 1 kW squirrel-cage induction machine. This paper provides a detailed overview of the hardware and software used along with the WTE control strategies such as MPPT and pitch control. The emulator reproduces dynamic characteristics both under step variations and arbitrary variation in the wind speed of a typical wind turbine (WT) of a wind energy conversion system (WECS). The usefulness of the setup has been benchmarked with previously verified WT test rigs made at the University of Manchester and Durham University in UK. Considering the fact that the rotor blades and electric subassemblies direct drive WTs are most susceptible to damage in practice, generator winding faults and rotor unbalance have been introduced and investigated using the terminal voltage and generated current. This wind turbine emulator (WTE) can be reconfigured or analyzed for condition monitoring without the need for real WTs.

Description: This paper presents a new neural network based model reference adaptive system (MRAS) to solve low speed problems for estimating rotor resistance in vector control of induction motor (IM). The MRAS using rotor flux as the state variable with a two layer online trained neural network rotor flux estimator as the adaptive model (FLUX-MRAS) for rotor resistance estimation is popularly used in vector control. In this scheme, the reference model used is the flux estimator using voltage model equations. The voltage model encounters major drawbacks at low speeds, namely, integrator drift and stator resistance variation problems. These lead to a significant error in the estimation of rotor resistance at low speed. To address these problems, an offline trained NN with data incorporating stator resistance variation is proposed to estimate flux, and used instead of the voltage model. The offline trained NN, modeled using the cascade neural network, is used as a reference model instead of the voltage model to form a new scheme named as “NN-FLUXMRAS.” The NN-FLUX-MRAS uses two neural networks, namely, offline trained NN as the reference model and online trained NN as the adaptive model. The performance of the novel NN-FLUX-MRAS is compared with the FLUX-MRAS for low speed problems in terms of integral square error (ISE), integral time square error (ITSE), integral absolute error (IAE) and integral time absolute error (ITAE). The proposed NN-FLUX-MRAS is shown to overcome the low speed problems in Matlab simulation.

Description: The recent trend in light emitting diode or LED lighting applications and their claimed energy saving capabilities together with their overall attractiveness has us all convinced that they really are a greener alternative to the compact fluorescent lights or CFL. As convincing as it seems, the actual energy saving capabilities of LEDs are yet to be proven scientifically or at the least, on an empirical level when compared to CFLs. This paper tackles the issue with the use of a solar cell by evaluating the photovoltaic current and voltage generated by the solar cell subjected to each lighting system. Graphical representations are drawn and a conclusion is then reached based on the amount of power generation in the solar cells in order to determine the energy saving capabilities of each lighting system and its efficiency. From the result, it has been found that an LED is 3.7 times more power efficient than a CFL based light source of equal wattage.

Description: Large-scale, grid-connected photovoltaic systems have become an essential part of modern electric power distribution systems. In this paper, a novel approach based on the Markov method has been proposed to investigate the effects of large-scale, grid-connected photovoltaic systems on the reliability of bulk power systems. The proposed method serves as an applicable tool to estimate performance (e.g., energy yield and capacity) as well as reliability indices. The Markov method framework has been incorporated with the multi-state models to develop energy states of the photovoltaic systems in order to quantify the effects of the photovoltaic systems on the power system adequacy. Such analysis assists planners to make adequate decisions based on the economical expectations as well as to ensure the recovery of the investment costs over time. The failure states of the components of photovoltaic systems have been considered to evaluate the sensitivity analysis and the adequacy indices including loss of load expectation, and expected energy not supplied. Moreover, the impacts of transitions between failures on the reliability calculations as well as on the long- term operation of the photovoltaic systems have been illustrated. Simulation results on the Roy Billinton test system has been shown to illustrate the procedure of the proposed frame work and evaluate the reliability benefits of using large-scale, grid-connected photovoltaic system on the bulk electric power systems. The proposed method can be easily extended to estimate the operating and maintenance costs for the financial planning of the photovoltaic system projects.

Description: This paper critically assesses the geopolitical and geo-economic impact of novel fuel resources on both resource exporters and importers. Presently, very strong political and economic forces drive the utilisation of domestic, unconventional oil and gas recovery in the West as these enhance energy security and ease balance of payment issues. The additional capacity generated by this trend has, supported by other effects such as Saudi Arabia’s decision to maintain current production, triggered a significant reduction of oil prices. Consequently, it is now oil exporters that struggle with the balance of payment issues and often these countries base their fiscal budget completely on fossil fuel revenues. In fact, these unconventional resources help turn the tide while oil exporters are now politically significantly weakened due to the increased energy sufficiency of the West. The catch is that the extraction of unconventional types of oil has many environmental implications. So, internalising the environmental externalities have to be considered. This paper, therefore, assesses, next to geopolitics and geo-economics, the environmental implications of this trend.

Description: Smart technologies when used in the traditional grid infrastructure will provide a different environment and working conditions in the grid by bringing the required smartness into the grid, called the smart grid. The smart grid can play a major role in the upcoming days to come because there is a necessity to integrate coordinated renewable energy resources into the grid and to operate the grids at a higher efficiency considering many aspects including reliability of the supply. Apart from this, there is a necessity to manage the demand supply gap in the smart grid by optimally scheduling the generators or by effectively scheduling the demand side resources instead of going for the traditional methods like partial or full load shedding. This paper presents an overview on the present state-of-the-art of smart grid technologies and broadly classifies the papers referred into two major areas, papers based on improvement of operational efficiency in smart grids and papers based on smartness in maintaining the demand supply gap. Some of the papers projected in this work also give a brief overview of the necessity of the smart grid.

Description: This paper proposes the generation scheduling approach for a microgrid comprised of conventional generators, wind energy generators, solar photovoltaic (PV) systems, battery storage, and electric vehicles. The electrical vehicles (EVs) play two different roles: as load demands during charging, and as storage units to supply energy to remaining load demands in the MG when they are plugged into the microgrid (MG). Wind and solar PV powers are intermittent in nature; hence by including the battery storage and EVs, the MG becomes more stable. Here, the total cost objective is minimized considering the cost of conventional generators, wind generators, solar PV systems and EVs. The proposed optimal scheduling problem is solved using the hybrid differential evolution and harmony search (hybrid DE-HS) algorithm including the wind energy generators and solar PV system along with the battery storage and EVs. Moreover, it requires the least investment.

Description: Recently, mixture of different oils at various proportions have been used as feedstock for biodiesel production. The primary aim is to improve fuel properties which are strongly influenced by the fatty acid composition of the individual oil that makes up the feedstock mix. The tropics are renowned for abundant oil-bearing crops of which palm kernel oil (PKO) from palm seed and groundnut oil (GNO) are prominent. This present paper investigated biodiesel production from hybrid oil (HO) of PKO (medium carbon chain and highly saturated oil) and GNO (long carbon chain and highly unsaturated oil) at 50/50 (v/v) blending. The principal fatty acids (FAs) in the HO are oleic (35.62%) and lauric acids (24.23%) with 47.80% of saturated FA and 52.26% of unsaturated FA contents. The chemical conversion of the oil to methyl ester (ME) gave 86.56% yield. Fuel properties of hybrid oil methyl ester (the HOME) were determined in accordance with standard test methods and were found to comply with both ASTM D6751 and EN 14214 standards. The oxidative stability, cetane number and kinematic viscosity (KV) of HOME were observed to be improved when compared with those of GNO methyl ester from single parent oil, which could be accredited to the improved FA composition of the HO. The KV (3.69 mm 2 /s) of HOME obtained in this paper was remarkably low compared with those reported in literature for most biodiesels. This value suggests better flow, atomization, spray and combustion of this fuel. Conclusively, the binary blend of oils can be a viable option to improve the fuel properties of biodiesel feedstock coupled with reduced cost.

Description: It is well known that the ambient temperature is a sensitive parameter which has a great effect on biology, technology, geology and even on human behavior. A prediction is a statement about an uncertain event. It is often, but not always, based upon experience or knowledge. Although guaranteed accurate information about the future is in many cases impossible, prediction can be useful to assist in making plans about possible developments. As a result, temperature profiles can be developed which accurately represent the expected ambient temperature exposure that this environment experiences during measurement. The ambient temperature over time is modeled based on the previous T min and T max data and using a Lagrange interpolation. To observe the comprehensive variation of ambient temperature the profile must be determined numerically. The model proposed in this paper can provide an acceptable way to measure the change in ambient temperature.

Description: The collision frequency function for aerosol particles has already been calculated for the free molecule regime and for the continuum range. The present work, taking into account the influence of internal force fields such as magnetic force, electric force and molecular forces, created by particles themselves, recalculated the collision frequency in the case of particles much smaller than the mean free path of the gas (free molecule regime). Attractive forces increase naturally the collision frequency, while repulsive forces decrease it. The calculation was performed for all types of central forces deriving from a potential, including Coulomb forces and Van der Waals forces.

Description: As the basis of modern industry, the roles materials play are becoming increasingly vital in this day and age. With many superior physical properties over conventional fluids, the low melting point liquid metal material, especially room-temperature liquid metal, is recently found to be uniquely useful in a wide variety of emerging areas from energy, electronics to medical sciences. However, with the coming enormous utilization of such materials, serious issues also arise which urgently need to be addressed. A biggest concern to impede the large scale application of room-temperature liquid metal technologies is that there is currently a strong shortage of the materials and species available to meet the tough requirements such as cost, melting point, electrical and thermal conductivity, etc. Inspired by the Material Genome Initiative as issued in 2011 by the United States of America, a more specific and focused project initiative was proposed in this paper—the liquid metal material genome aimed to discover advanced new functional alloys with low melting point so as to fulfill various increasing needs. The basic schemes and road map for this new research program, which is expected to have a worldwide significance, were outlined. The theoretical strategies and experimental methods in the research and development of liquid metal material genome were introduced. Particularly, the calculation of phase diagram (CALPHAD) approach as a highly effective way for material design was discussed. Further, the first-principles (FP) calculation was suggested to combine with the statistical thermodynamics to calculate the thermodynamic functions so as to enrich the CALPHAD database of liquid metals. When the experimental data are too scarce to perform a regular treatment, the combination of FP calculation, cluster variation method (CVM) or molecular dynamics (MD), and CALPHAD, referred to as the mixed FP-CVMCALPHAD method can be a promising way to solve the problem. Except for the theoretical strategies, several parallel processing experimental methods were also analyzed, which can help improve the efficiency of finding new liquid metal materials and reducing the cost. The liquid metal material genome proposal as initiated in this paper will accelerate the process of finding and utilization of new functional materials.

Description: “Partial pressure” in humid air is a question very much concerned by scientists and no satisfactory answer has been found to date. This paper proposes a novel method to obtain the “partial pressures” of the water vapor and dry air in humid air. The results obtained by the proposed method are quite different from that obtained by Dalton’s partial pressure law. The fundamental behaviors of water vapor and dry air are studied in depth in wide pressure and temperature ranges. Semi-permeable membrane models are proposed and applied for both saturated and unsaturated humid air. “Improvement factors” are developed to quantitatively describe the magnitude of the interaction between dissimilar molecules. One discovery is that the “partial pressure” of the water vapor in saturated humid air equals P s , rather than ( f · P s ) which was formerly believed. The other is that the interaction between dissimilar molecules may be omitted when temperature is above “cutting-off temperature” for unsaturated humid air. This paper satisfactorily answers the quest of “partial pressures” in humid air from a new perspective.

Description: In estimating emissions reductions brought about by renewables in China, much of existing research assumes that renewables displace coal power. In this paper, this assumption is challenged and the potential environmental effects of photovoltaic (PV) power in North-west China are reevaluated when the marginal generator actually being displaced is taken into account. The annual PV power generation in the North-west Grid is estimated, in this paper, to be as high as 17900GW·h in 2015, roughly equaling to the output of 1.5 nuclear power plants in the US today. The total associated emission reduction in 2015 will at most be 0.36 percent of SO 2 and 0.25 percent of NO x emissions from their 2010 levels in China. Further, PV power may render no emissions reduction at all if it displaces hydropower, which is often used to meet peak demand in the North-west Grid in China. These results imply that a more cost-effective area of focus in the short-term may be on desulfurization and denitrification technologies for coal plants.

Description: In this paper, a simple strategy based differential evolution was proposed for solving the problem of multi-objective environmental optimal power flow considering a hybrid model (Wind-Shunt-FACTS). The DE algorithm optimized simultaneously a combined vector control based active power of wind sources and reactive power of multi STATCOM exchanged with the electrical power system to minimize fuel cost and emissions. The proposed strategy was examined and applied to the standard IEEE 30-bus with smooth cost function to solve the problem of security environmental economic dispatch considering multi distributed hybrid model based wind and STATCOM controllers. In addition, the proposed approach was validated on a large practical electrical power system 40 generating units considering valve point effect. Simulation results demonstrate that choosing the installation of multi type of FACTS devices in coordination with many distributed wind sources is a vital research area.

Description: The implementation of a simple power converter for a wound rotor induction generator employing a three phase diode bridge rectifier and a line commutated inverter in the rotor circuit for super synchronous speeds has been proposed. The detailed working of the system in power smoothing mode and maximum power point tracking mode is presented. The current flow in the rotor circuit is controlled (by controlling the firing angle of the line commutated inverter) for controlling the stator power in both the modes. An 8 bit PIC microcontroller has been programmed to vary the firing angle of the line commutated inverter. Experiments have been carried out on a 3-phase, 3.73 kW, 400 V, 50 Hz, 4-pole, 1500 r/min wound rotor induction generator and the results obtained with the generator supplying power in both the modes are furnished. The complete scheme has been modeled using MATLAB/SIMULINK blocks and a simulation study has been conducted. The experimental waveforms are compared with the simulation results and a very close agreement between them is observed.

Description: The energy consumption of office buildings in China has been growing significantly in recent years. Obviously, there are significant relationships between building envelope and the energy consumption of office buildings. The 8 key building envelope influencing factors were found in this paper to evaluate their effects on the energy consumption of the air-conditioning system. The typical combinations of the key influencing factors were performed in Trnsy simulation. Then on the basis of the simulated results, the multiple regression models were developed respectively for the four climates of China—hot summer and warm winter, hot summer and cold winter, cold, and severely cold. According to the analysis of regression coefficients, the appropriate building envelope design schemes were discussed in different climates. At last, the regression model evaluations consisting of the simulation evaluations and the actual case evaluations were performed to verify the feasibility and accuracy of the regression models. The error rates are within ±5% in the simulation evaluations and within ±15% in the actual case evaluations. It is believed that the regression models developed in this paper can be used to estimate the energy consumption of office buildings in different climates when various building envelope designs are considered.

Description: Unit commitment (UC) is an optimization problem used to determine the operation schedule of the generating units at every hour interval with varying loads under different constraints and environments. Many algorithms have been invented in the past five decades for optimization of the UC problem, but still researchers are working in this field to find new hybrid algorithms to make the problem more realistic. The importance of UC is increasing with the constantly varying demands. Therefore, there is an urgent need in the power sector to keep track of the latest methodologies to further optimize the working criterions of the generating units. This paper focuses on providing a clear review of the latest techniques employed in optimizing UC problems for both stochastic and deterministic loads, which has been acquired from many peer reviewed published papers. It has been divided into many sections which include various constraints based on profit, security, emission and time. It emphasizes not only on deregulated and regulated environments but also on renewable energy and distributed generating systems. In terms of contributions, the detailed analysis of all the UC algorithms has been discussed for the benefit of new researchers interested in working in this field.

Description: A deep analysis of orbiting scroll wraps was conducted in this paper by using ANSYS and SolidWorks. Through the modal analysis, the involute of the circle profile orbiting scroll wrap demonstrated a large span in natural frequencies, which led to more superiority in avoiding structural resonances. Based on the dynamic harmonic analysis, loads of frequency changes were gained and the stress and strain distribution of the orbiting scroll wrap in the most dangerous working conditions were obtained, which determined the segments with maximum stress and strain-displacement properties. Two paths defined to elucidate further the structural characteristics of the exhaust chamber provided evidence for the initial correction of orbiting wraps. The results of the present study offer a theoretical basis for the design and manufacture of scroll wraps, and providing a new way to evaluate different scroll wraps.

Description: This paper presents the complete mathematical model and predicts the performance of switched reluctance generator with time average and small signal models. The complete mathematical model is developed in three stages. First, a switching model is developed based on quasi-linear inductance profile. Next, based on the switching behaviour, a time average model is obtained to measure the difference between the excitation and generation time in each switching cycle. Finally, to track control voltage and current wave shapes, a small signal model is designed. The effectiveness of the complete multilevel model combining electrical machine, power converter, load and control with programming language is demonstrated through simulations. A PI controller is used for controlling the voltage of the generator. The results presented show that the controller exhibits accurate tracking control of load voltage under different operating conditions. This demonstrates that the proposed model is able to perform an accurate control of the generated output voltage even in transient situations. The simulation is performed to choose the control parameters and study the performance of switched reluctance generator prior to its actual implementation. Initial experimental results are presented using NI-Data acquisition card to control the output power according to load requirements.

Description: Recently, real-time simulation of renewable energy sources are indispensible for evaluating the performance of the maximum power point tracking (MPPT) controller, especially in the photovoltaic (PV) system in order to reduce cost in the testing phase. Nowadays, real time PV simulators are obtained by using analog and/or digital components. In this paper, a real-time simulation of a PV system with a boost converter was proposed using only the digital signal processor (DSP) processor with two DC voltage sources to emulate the temperature and irradiation in the PV system. AMATLAB/ Simulink environment was used to develop the real-time PV system with a boost converter into a C-program and build it into a DSP controller TMS320F28335. Besides, the performance of the real-time DSP-based PV was tested in different temperature and irradiation conditions to observe the P-V and V-I characteristics. Further, the performance of the PV with a boost converter was tested at different temperatures and irradiations using MPPT algorithms. This scheme was tested through simulation and the results were validated with that of standard conditions given in the PV data sheets. Implementation of this project helped to attract more researchers to study renewable energy applications without real sources. This might facilitate the study of PV systems in a real-time scenario and the evaluation of what should be expected for PV modules available in the market.

Description: Effective utilization of renewable energy sources and efficient management of electric energy are essential for any developing countries like India. This can be envisioned through the implementation of concepts of smart grid (SG). One of the key requisites for SG implementation is that the grid should be completely observable. Renovation of conventional Indian power grid to a SG necessitates incorporation of the phasor measurement units (PMUs) in the present power grid measurement and monitoring system. Since the cost of PMU is high and any bus containing a PMU makes the neighboring connected buses observable, optimal placement of PMUs is very important for complete observability of the grid. This paper proposes optimal redundant geographical locations in the northern, eastern and north-eastern regions of Indian power grid for PMU placement. The PMUs installed in these geographical locations will make the grid completely observable and maintain the observability under the conditions of failure of some PMUs or branch outages. Integer linear programming has been used for finding the optimal PMU locations. The results proposed in this paper can be a stepping stone for revamping the Indian power grid to a SG ensuring complete observability during different contingency conditions.

Description: If the heat of road surface can be stored in summer, the road surface temperature will be decreased to prevent permanent deformation of pavement. Besides, if the heat stored is released, it can supply heat for buildings or raise the road surface temperature for snow melting in winter. A road-solar energy system was built in this study, and the heat transfer mechanism and effect of the system were analyzed according to the monitored solar radiant heat, the solar energy absorbed by road and the heat stored by soil. The results showed that the road surface temperature was mainly affected by solar radiation, but the effect is hysteretic in nature. The temperature of the solar road surface was 3°C–6°C lower than that of the ordinary road surface. The temperature of the solar road along the vertical direction was 2°C–5°C lower than that of the ordinary road. The temperature difference increased as the distance to the heat transfer tubes decreased. The average solar collector efficiency of the system was 14.4%, and the average solar absorptivity of road surface was 36%.

Description: The aim of non-intrusive appliance load monitoring (NIALM) is to disaggregate the energy consumption of individual electrical appliances from total power consumption utilizing non-intrusive methods. In this paper, a systematic approach to ON-OFF event detection and clustering analysis for NIALM were presented. From the aggregate power consumption data set, the data are passed through median filtering to reduce noise and prepared for the event detection algorithm. The event detection algorithm is to determine the switching of ON and OFF status of electrical appliances. The goodness-of-fit (GOF) methodology is the event detection algorithm implemented. After event detection, the events detected were paired into ON-OFF pairing appliances. The results from the ON-OFF pairing algorithm were further clustered in groups utilizing the K -means clustering analysis. The K -means clustering were implemented as an unsupervised learning methodology for the clustering analysis. The novelty of this paper is the determination of the time duration an electrical appliance is turned ON through combination of event detection, ON-OFF pairing and K -means clustering. The results of the algorithm implementation were discussed and ideas on future work were also proposed.

Description: The analysis of the failure mechanics, namely hydrogen permeation of vacuum insulated tubing (VIT), indicated that the failure of VIT could be decreased but could not be avoided. To solve this problem, some measures by using non-vacuum materials were proposed and analyzed in this paper. The results show that to fill the tubing with foam-glass beads or high pressure argon may lead to a good performance.

Description: This paper focuses on modeling and performance predetermination of a photovoltaic (PV) system with a boost converter fed permanent magnet direct current (PMDC) motor-centrifugal pump load, taking the converter losses into account. Sizing is done based on the maximum power generated by the PV array at the average irradiation. Hence optimum sizing of the PV array for the given irradiation at the geographical location of interest is obtained using the predetermined values. The analysis presented here involves systems employing maximum power point tracking (MPPT) as they are more efficient than directly coupled systems. However, the voltage and power of the motor might rise above rated values for irradiations greater than the average when employing MPPT, hence a control scheme has been proposed to protect the PMDC motor from being damaged during these conditions. This control scheme appropriately chooses the optimum operating point of the system, ensuring long-term sustained operation. The numerical simulation of the system is performed in Matlab/Simulink and is validated with experimental results obtained from a 180 V, 0.5 hp PMDC motor coupled to a centrifugal pump. The operation of the system with the proposed control scheme is verified by varying the irradiation levels and the relevant results are presented.

Description: Conventional power grids across the globe are reforming to smart power grids with cutting edge technologies in real time monitoring and control methods. Advanced real time monitoring is facilitated by incorporating synchrophasor measurement units such as phasor measurement units (PMUs) to the power grid monitoring system. Several physical and economic constraints limit the deployment of PMUs in smart power grids. This paper proposes a pragmatic multi-stage simulated annealing (PMSSA) methodology for finding the optimal locations in the smart power grid for installing PMUs in conjunction with existing conventional measurement units (CMUs) to achieve a complete observability of the grid. The proposed PMSSA is much faster than the conventional simulated annealing (SA) approach as it utilizes controlled uphill and downhill movements during various stages of optimization. Moreover, the method of integrating practical phasor measurement unit (PMU) placement conditions like PMU channel limits and redundant placement can be easily handled. The efficacy of the proposed methodology has been validated through simulation studies in IEEE standard bus systems and practical regional Indian power grids.

Description: In this paper, the effect of adding an antioxidant mixture in Jatropha biodiesel as fuel, in a single cylinder, direct injection compression ignition engine was experimentally investigated and the level of pollutants in the exhaust and performance characteristics of the engine were analyzed. Nine test fuels were prepared with three antioxidants, namely, Succinimide (C 4 H 5 NO 2 ), N , N -dimethyl- p -phenylenediamine-dihydrochloride (C 8 H 14 Cl 2 N 2 ), and N -phenyl- p -phenylenediamine (C 6 H 5 NHC 6 H 4 NH 2 ) added to neat biodiesel at 500 parts per million (ppm), 1000 ppm and 2000 ppm and the observed experimental results were compared with those of neat biodiesel and neat diesel as base fuels. The comparison showed that NO emission was reduced drastically for the test fuels with the antioxidant addition of 2000 ppm. The maximum reduction of 10% of NO emission was observed for the antioxidant mixture in neat biodiesel, with a slight increase in unburned HC, CO and smoke opacity. In addition, the obtained experimental results reveal that the addition of two antioxidants as mixture in neat biodiesel caused improved NO emission reduction for all test fuels.

Description: This paper aims to develop a new microemulsions system comprising diesel and palm oil methyl ester (PME) that have the potential to be used as alternative fuels for diesel engines. The water-in-diesel-biodiesel microemulsions were prepared by applying PME mixed with diesel, non-ionic surfactants, co-surfactants and water to make the water-in-oil (W/O) microemulsion system. This microemulsified fuel was achieved through low-energy microemulsification by using the constant composition method. The diesel used was mixed with four different concentrations of PME, i.e., 10% (w/w) (B10), 20% (w/w) (B20), 30% (w/w) (B30) and neat diesel (B0). The amount of water was fixed at 20%(w/w). The phase behavior of the water/mixed non-ionic surfactant/diesel-PME system were studied by constructing pseudoternary phase diagrams with the goal of formulating optimized systems. The results showed that the microemulsions were formed and stabilized with a mixture of non-ionic surfactants at a weight ratio of 80:20 at 20% (w/w), and with mixed co-surfactants at a weight ratio of 25:75, 20:80 and 10:90 for B0, B10, B20 and B30 respectively. The particle size, kinematic viscosity at 40°C, refractive index, density, heating value, cloud point, pour point and flash point of the selected water-in-diesel microemulsion were 19.40 nm (polydispersity of 0.012), 12.86 mm 2 /s, 1.435, 0.8913 g/mL, 31.87 MJ/kg, 7.15°C, 10.5°C and 46.5°C respectively. The corresponding values of the water-in-diesel-PME selected were 20.72 nm to 23.74 nm, 13.02 mm 2 /s to 13.29 mm 2 /s, 1.442, 0.8939 g/mL to 0.8990 g/mL, 31.45 MJ/kg to 27.34 MJ/kg, 7.2°C to 6.8°C, 8.5°C to 1.5°C and 47.5°C to 52.0°C. These preliminary findings were further studied as potential fuels for diesel engines.

Description: The optimized structure strength design and finite element analysis method for very high pressure (VHP) rotors of the 700°C ultra-super-critical (USC) steam turbine are presented. The main parameters of steam and the steam thermal parameters of blade stages of VHP welded rotors as well as the start and shutdown curves of the steam turbine are determined. The structure design feature, the mechanical models and the typical position of stress analysis of the VHP welded rotors are introduced. The steady and transient finite element analysis are implemented for steady condition, start and shutdown process, including steady rated condition, 110% rated speed, 120% rated speed, cold start, warm start, hot start, very hot start, sliding-pressure shutdown, normal shutdown and emergency shutdown, to obtain the temperature and stress distribution as well as the stress ratio of the welded rotor. The strength design criteria and strength analysis results of the welded rotor are given. The results show that the strength design of improved structure of the VHP welded rotor of the 700°C USC steam turbine is safe at the steady condition and during the transient start or shutdown process.

Description: This paper investigates a new operation strategy for photovoltaic (PV) systems, which improves the overall reliability of the system as a result of the improvement in the reliability of the critical components. First, a mathematical model is proposed using the fault tree analysis (FTA) to estimate the reliability of the PV systems in order to find the suitable maintenance strategies. The implementations demonstrate that it is essential to employ smart maintenance plans and monitor the identified most critical components of PV systems. Then, an innovative analytical method based on the Markov process is presented to model smart operation plans in PV systems. The impact of smart operation strategy on the PV systems is then evaluated. The objective of this paper is to develop plans for improving the reliability of PV systems. A series of case studies have been conducted to demonstrate the importance of smart operation strategies for PV systems as well as the applicability and feasibility of the proposed method.

Description: The major advantages of homogeneous charge compression ignition (HCCI) are high efficiency in combination with low NO x -emissions. However, one of the major challenges with HCCI is the control of higher peak pressures which may damage the engine, limiting the HCCI engine life period. In this paper, an attempt is made to analyze computationally the effect of induction swirl in controlling the peak pressures of an HCCI engine under various operating parameters. A single cylinder 1.6 L reentrant piston bowl diesel engine is chosen. For computational analysis, the ECFM-3Z model of STAR–CD is considered because it is suitable for analyzing the combustion processes in SI and CI engines. As an HCCI engine is a hybrid version of SI and CI engines, the ECFM- 3Z model with necessary modifications is used to analyze the peak pressures inside the combustion chamber. The ECFM-3Z model for HCCI mode of combustion is validated with the existing literature to make sure that the results obtained are accurate. Numerical experiments are performed to study the effect of varying properties like speed of the engine, piston bowl geometry, exhaust gas recirculation (EGR) and equivalence ratio under different swirl ratios in controlling the peak pressures inside the combustion chamber. The results show that the swirl ratio has a considerable impact on controlling the peak pressures of HCCI engine. A reduction in peak pressures are observed with a swirl ratio of 4 because of reduced in cylinder temperatures. The combined effect of four operating parameters, i.e., the speed of the engine, piston bowl geometry, EGR, and equivalence ratio with swirl ratios suggest that lower intake temperatures, reentrant piston bowl, higher engine speeds and higher swirl ratios are favorable in controlling the peak pressures.

Description: Over the last decade, India has started to concentrate earnestly on renewable energy. The Indian government, as well as different state governments, are adopting policy instruments such as feed in tariff, captive consumption, renewable purchase obligation and generation based incentive etc. aimed at renewable energy development. This paper evaluates the effectiveness of state level incentives for the development of wind energy in India. Fixed effect panel data modelling technique of econometric analysis is used to analyse the data of 26 Indian states in 11 years. The results show that feed in tariff and captive consumption are the significant predictors of wind energy development. However, renewable purchase obligation does not affect wind energy significantly.

Description: Based on energy conservation equation and Darcy’s law, a model of beach well infiltration intake system applied in a seawater source heat pump system was established. The model consists of the seawater seepage and the heat transfer process. A porous medium model in a software named FLUENT was applied to simulate the seepage and the heat transfer process. This model was also validated by field experiment conducted on the seashore in Tianjin, China. The maximum relative error between simulation results and experimental results was 2.1% (less than 5%), which was acceptable in engineering application. The porosity and coefficient of thermal conductivity of the aquifer soil were determined to be 0.49 W/(m·K) and 1.46 W/(m·K), respectively in the simulation. In addition, the influencing factors of pumping water of beach well were also analyzed. The pumping water was found to increase when the distance between the beach well and the impervious boundary becomes longer, when the distance between the beach well and the supplying water source shortens, when the diameter of the beach well enlarges, and the drawdown enlarges.

Description: This paper addresses the attuned use of multiconverter flexible alternative current transmission systems (M-FACTS) devices and demand response (DR) to perform congestion management (CM) in the deregulated environment. The strong control capability of the M-FACTS offers a great potential in solving many of the problems facing electric utilities. Besides, DR is a novel procedure that can be an effective tool for reduction of congestion. A market clearing procedure is conducted based on maximizing social welfare (SW) and congestion as network constraint is paid by using concurrently the DR and M-FACTS. A multi-objective problem (MOP) based on the sum of the payments received by the generators for changing their output, the total payment received by DR participants to reduce their load and M-FACTS cost is systematized. For the solution of this problem a nonlinear time-varying evolution (NTVE) based multi-objective particle swarm optimization (MOPSO) style is formed. Fuzzy decision-making (FDM) and technique for order preference by similarity to ideal solution (TOPSIS) approaches are employed for finding the best compromise solution from the set of Pareto-solutions obtained through multi-objective particle swarm optimization-nonlinear time-varying evolution (MOPSO-NTVE). In a real power system, Azarbaijan regional power system of Iran, comparative analysis of the results obtained from the application of the DR & unified power flow controller (UPFC) and the DR & M-FACTS are presented.

Description: This paper explored the feasibility and benefit of CO 2 utilization as gasifying agent in the autothermal gasification process. The effects of CO 2 injection on reaction temperature and producer gas composition were examined in a pilot scale downdraft gasifier by varying the CO 2 /C ratio from 0.6 to 1.6. O 2 was injected at an equivalence ratio of approximately 0.33–0.38 for supplying heat through partial combustion. The results were also compared with those of air gasification. In general, the increase in CO 2 injection resulted in the shift of combustion zone to the downstream of the gasifier. However, compared with that of air gasification, the long and distributed high temperature zones were obtained in CO 2 -O 2 gasification with a CO 2 /C ratio of 0.6–1.2. The progress of the expected CO 2 to CO conversion can be implied from the relatively insignificant decrease in CO fraction as the CO 2 /C ratio increased. The producer gas heating value of CO 2 -O 2 gasification was consistently higher than that of air gasification. These results show the potential of CO 2 -O 2 gasification for producing high quality producer gas in an efficient manner, and the necessity for more work to deeply imply the observation.

Description: Harvesting the energy from ocean waves is one of the greatest attractions for energy engineers and scientists. Till date, plenty of methods have been adopted to harvest the energy from the ocean waves. However, due to technological and economical complexity, it is intricate to involve the majority of these energy harvesters in the real ocean environment. Effective utilization and sustainability of any wave energy harvester depend upon its adaptability in the irregular seasonal waves, situation capability in maximum energy extraction and finally fulfilling the economic barriers. In this paper, the front end energy conversions are reviewed in detail which is positioned in the first stage of the wave energy converter among other stages such as power take off (PTO) and electrical energy conversion. If the recent development of these front end energy conversion is well known then developing wave energy converter with economic and commercial viability is possible. The aim of this review is to provide information on front end energy conversion of a point absorber and emphasize the strategies and calamity to be considered in designing such kinds of devices to improve the energy harvesting competence. This will be useful to the engineers for speeding up the development of a matured point absorbing type wave energy converter.

Description: Biodiesel is an alternative fuel to replace fossilbased diesel fuel. It has fuel properties similar to diesel which are generally determined experimentally. The experimental determination of various properties of biodiesel is costly, time consuming and a tedious process. To solve these problems, artificial neural network (ANN) has been considered as a vital tool for estimating the fuel properties of biodiesel, especially from its fatty acid (FA) composition. In this study, four ANNs have been designed and trained to predict the cetane number (CN), flash point (FP), kinematic viscosity (KV) and density of biodiesel using ANN with logsig and purelin transfer functions in the hidden layer of all the networks. The five most prevalent FAs from 55 feedstocks found in the literature utilized as the input parameters for the model are palmitic, stearic, oleic, linoleic and linolenic acids except for density network with a sixth parameter (temperature). Other FAs that are present in the biodiesels have been considered based on the number of carbon atom chains and the level of saturation. From this study, the prediction accuracy and the average absolute deviation of the networks are CN (96.69%; 1.637%), KV (95.80%; 1.638%), FP (99.07%; 0.997%) and density (99.40%; 0.101%). These values are reasonably better compared to previous studies on empirical correlations and ANN predictions of these fuel properties found in literature. Hence, the present study demonstrates the ability of ANN model to predict fuel properties of biodiesel with high accuracy.

Description: A novel controller is proposed to regulate the DC-link voltage of a single phase active power filter (SPAPF). The proposed switched fractional controller (SFC) consists of a conventional PI controller, a fractional order PI (FO-PI) controller and a decision maker that switches between them. Commonly, the conventional PI controller is used in regulation loops due to its advantages in steady-state but it is limited in transient state. On the other hand, the FO-PI controller overcomes these drawbacks but it causes dramatic degradation in control performances in steady-state because of the fractional calculus theory and the approximation method used to implement this kind of controller. Thus, the purpose of this paper is to switch to the PI controller in steady-state to obtain the best power quality and to switch to the FO-PI controller when external disturbances are detected to guarantee a fast transient state. To investigate the efficiency and accuracy of the SFC considering all robustness tests, an experimental setup has been established. The results of the SFC fulfill the requirements, confirm its high performances in steady and transient states and demonstrate its feasibility and effectiveness. The experiment results have satisfied the limit specified by the IEEE harmonic standard 519.

Description: The aim of this paper is simultaneous minimization of hydrothermal units to reach the best solution by employing an improved artificial bee colony (ABC) algorithm in a multi-objective function consisting of economic dispatch (ED) considering the valve-point effect and pollution function in power systems in view of the hot water of the hydro system. In this type of optimization problem, all practical constraints of units were taken into account as much as possible in order to comply with the reality. These constraints include the maximum and minimum output power of units, the constraints caused by the balance between supply and demand, the impact of pollution, water balance, uneven production curve considering the valve-point effect and system losses. The proposed algorithm is applied on the studied system, and the obtained results indifferent operating conditions are analyzed. To investigate in various operating conditions, different load profiles in 12 h are taken into account. The obtained results are compared with those of the other methods including the genetic algorithm (GA), the Basu technique, and the improved genetic algorithm. Fast convergence is one of this improved algorithm features.

Description: The higher heating value of five types of nonwoody biomass and their torrefaction char was predicted and compared with the experimental data obtained in this paper. The correlation proposed in this paper and the ones suggested by previous researches were used for prediction. For prediction using proximate analysis data, the mass fraction of fixed carbon and volatile matter had a strong effect on the higher heating value prediction of torrefaction char of non-woody biomass. The high ash fraction found in torrefied char resulted in a decrease in prediction accuracy. However, the prediction could be improved by taking into account the effect of ash fraction. The correlation developed in this paper gave a better prediction than the ones suggested by previous researches, and had an absolute average error (AAE) of 2.74% and an absolute bias error (ABE) of 0.52%. For prediction using elemental analysis data, the mass fraction of carbon, hydrogen, and oxygen had a strong effect on the higher heating value, while no relationship between the higher heating value and mass fractions of nitrogen and sulfur was discovered. The best correlation gave an AAE of 2.28% and an ABE of 1.36%.

Description: This paper deals with robust direct power control of a grid-connected brushless doubly-fed induction generator(BDFIG). Using a nonlinear feedback linearization strategy, an attempt is made to improve the desired performances by controlling the generated stator active and reactive power in a linear and decoupled manner. Therefore, to achieve this objective, the Lyapunov approach is used associated with a sliding mode control to guarantee the global asymptotical stability. Thus, an optimal operation of the BDFIG in sub-synchronous operation is obtained as well as the stator power flows with the possibility of keeping stator power factor at a unity. The proposed method is tested with the Matlab/Simulink software. Simulation results illustrate the performances and the feasibility of the designed control.

Description: Fabrication of modern multi-crystalline silicon solar cells involves multiple processes that are thermally intensive. These include emitter diffusion, thermal oxidation and firing of the metal contacts. This paper illustrates the variation and potential effects upon recombination in the wafers due to these thermal processes. The use of light emitter diffusions more compatible with selective emitter designs had a more detrimental effect on the bulk lifetime of the silicon than that of heavier diffusions compatible with a homogenous emitter design and screen-printed contacts. This was primarily due to a reduced effectiveness of gettering for the light emitter. This reduction in lifetime could be mitigated through the use of a dedicated gettering process applied before emitter diffusion. Thermal oxidations could greatly improve surface passivation in the intragrain regions, with the higher temperatures yielding the highest quality surface passivation. However, the higher temperatures also led to an increase in bulk recombination either due to a reduced effectiveness of gettering, or due to the presence of a thicker oxide layer, which may interrupt hydrogen passivation. The effects of fast firing were separated into thermal effects and hydrogenation effects. While hydrogen can passivate defects hence improving the performance, thermal effects during fast firing can dissolve precipitating impurities such as iron or de-getter impurities hence lower the performance, leading to a poisoning of the intra-grain regions.

Description: Recently, renewable energy sources such as wind power and photovoltaic (PV) are receiving a wide acceptance because they are inexhaustible and nonpolluting. Renewable energy sources are intermittent ones because of climate changes in wind speed and solar irradiance. Due to the continuous demand growth and the necessity for efficient and reliable electricity supply, there is a real need to increase the penetration of gas technologies in power grids. The Canadian government and stakeholders are looking for ways to increase the reliability and sustainability of power grid, and gas-power technologies may provide a solution. This paper explores the integration of gas and renewable generation technologies to provide a qualified, reliable, and environmentally friendly power system while satisfying regional electricity demands and reducing generation cost. Scenarios are evaluated using four key performance indicators (KPIs), economic, power quality, reliability, and environmental friendliness. Various scenarios outcomes are compared based on the defined performance indices. The proposed scenario analysis tool has three components, the geographic information system (GIS) for recording transmission and distribution lines and generation sites, the energy semantic network (ESN) knowledgebase to store information, and an algorithm created in Matlab/Simulink for evaluating scenarios. To interact with the scenario analysis tool, a graphical user interface (GUI) is used where users can define the desired geographic area, desired generation percentage via gas technology, and system parameters. To evaluate the effectiveness of the proposed method, the regional zone of the province of Ontario and Toronto are used as case studies.

Description: Globally, solar energy is expected to play a significant role in the changing face of energy economies in the near future. However, the variability of this resource has been the main barrier for solar energy development in most locations around the world. This paper investigated the distribution and variability of solar radiation using the a 10-year (2006 to 2015) data collected at Sørås meteorological station located at latitude 59° 39′ N and longitude 10° 47′E, about 93.3 m above sea level (about 30 km from Oslo), in south-eastern part of Norway. It is found that on annual basis, the total number of days with a global solar radiation of less than 1 kWh/(m 2 ∙d) is 120 days while the total number of days with an expected global solar radiation greater than 3 kWh/(m 2 ∙d) is 156 days (42.74%) per year. The potential energy output from a horizontally placed solar collector in these 156 days is approximately 75% of the estimated annual energy output. In addition, it is found that the inter-annual coefficient of variation of the global solar radiation is 4.28%, while that of diffuse radiation is 4.96%.

Description: Energy-saving awareness of heat users and heating enterprises can be stimulated by implementing heat metering for public buildings and by establishing scientific and reasonable policies for heat prices in China. In this paper, a two-part heat price for public buildings in Tianjin is introduced, which divides the heat price into a basic part and a metering part. According to the statistical analysis of information collected from two pilot heating enterprises, the specific heat load for public buildings in Tianjin is calculated, and three candidate schemes of heat price are proposed. A simulation of heat cost is also conducted, and the benefits for both heat users and heating enterprises are balanced. Finally, the two-part heat price for public buildings in Tianjin is determined: the basic heat price is recommended to be 20 CNY/m 2 , and the metering heat price is recommended to be 76.10 CNY/GJ. Such a price could be implemented in the initial stage of heat metering for public buildings in Tianjin.

Description: To increase the output efficiency of a photovoltaic (PV) system, it is important to apply an efficient maximum power point tracking (MPPT) technique. This paper describes the analysis, the design and the experimental implementation of the tracking methods for a standalone PV system, using two approaches. The first one is the constant voltage (CV) MPPT method based on the optimum voltage, which was deduced experimentally, and considered as a reference value to extract the optimum power. The second one is the increment conductance (Inc- Cond) MPPT method based on the calculation of the power derivative extracted by the installation. The output controller can adjust the duty ratio to the optimum value. This optimum duty ratio is the input of a DC/DC boost converter which feeds a set of Moto-pump via a DC/AC inverter. This paper presents the details of the two approaches implemented, based on the system performance characteristics. Contributions are made in several aspects of the system, including converter design, system simulation, controller programming, and experimental setup. The MPPT control algorithms implemented extract the maximum power point (MPP), with satisfactory performance and without steady-state oscillation. MATLAB/Simulink and dSpace DS1104 are used to conduct studies and implement algorithms. The two proposed methods have been validated by implementing the performance of the PV pumping systems installed on the roof of the research laboratory in INSAT Tunisia. Experimental results verify the feasibility and the improved functionality of the system.

Description: The aims of this paper is to investigate the effects of various materials inside the solar still on the increase of the productivity of potable water. Here, blue metal stones and cow dung cakes were used as materials. To investigate their effect, three identical solar stills with an effective area of 1 m square made from locally available materials were tested in climate conditions of Mehsana (23°50′ N 72° 23′). The first and second solar stills were filled with blue metal, stones and cow dung cakes, while the third one was taken as a reference which consisted of only blue paint at the basin. The experiments show that blue metal stones have the highest distillate output at daytime, followed by cow dung cakes solar still and reference solar still. On the other hand, the overall distillate output of blue metal stones and cow dung cakes at daytime as well as at night were 35% and 20% compared with that of reference solar still.

Description: In most isolated sites situated in south Algeria, the diesel generators are the major source of electrical energy. Indeed, the power supply of these remote regions still poses order problems (technical, economical and ecological). The electricity produced with the help of diesel generators is very expensive and responsible for CO2 emission. These isolated sites have significant wind energy potential. Hence, the use of twinning wind-diesel is widely recommended, especially to reduce operating deficits. The objective of this paper is to study the global modeling of a hybrid system which compounds wind turbine generator, diesel generator and storage system. This model is based on the control strategy to optimize the functioning of the hybrid system and to consolidate the gains to provide proper management of energy sources (wind, diesel, battery) depending on the load curve of the proposed site. The management is controlled by a controller which ensures the opening/closing of different power switches according to meteorological conditions (wind speed, air mass, temperature, etc).

Description: The purpose of this paper is to improve the control performance of the variable speed, constant frequency doubly-fed induction generator in the wind turbine generation system by using fuzzy logic controllers. The control of the rotor-side converter is realized by stator flux oriented control, whereas the control of the grid-side converter is performed by a control strategy based on grid voltage orientation to maintain the DC-link voltage stability. An intelligent fuzzy inference system is proposed as an alternative of the conventional proportional and integral (PI) controller to overcome any disturbance, such as fast wind speed variation, short grid voltage fault, parameter variations and so on. Five fuzzy logic controllers are used in the rotor side converter (RSC) for maximum power point tracking (MPPT) algorithm, active and reactive power control loops, and another two fuzzy logic controllers for direct and quadratic rotor currents components control loops. The performances have been tested on 1.5MW doubly-fed induction generator (DFIG) in a Matlab/Simulink software environment.

Description: In recent years, many different techniques are applied in order to draw maximum power from photovoltaic (PV) modules for changing solar irradiance and temperature conditions. Generally, the output power generation of the PV system depends on the intermittent solar insolation, cell temperature, efficiency of the PV panel and its output voltage level. Consequently, it is essential to track the generated power of the PV system and utilize the collected solar energy optimally. The aim of this paper is to simulate and control a grid-connected PV source by using an adaptive neuro-fuzzy inference system (ANFIS) and genetic algorithm (GA) controller. The data are optimized by GA and then, these optimum values are used in network training. The simulation results indicate that the ANFIS-GA controller can meet the need of load easily with less fluctuation around the maximum power point (MPP) and can increase the convergence speed to achieve the MPP rather than the conventional method. Moreover, to control both line voltage and current, a grid side P/Q controller has been applied. A dynamic modeling, control and simulation study of the PV system is performed with the Matlab/Simulink program.

Description: Online estimation of rotor resistance is essential for high performance vector controlled drives. In this paper, a novel modified neural algorithm has been identified for the online estimation of rotor resistance. Neural based estimators are now receiving active consideration as they have a number of advantages over conventional techniques. The training algorithm of the neural network determines its learning speed, stability, weight convergence, accuracy of estimation, speed of tracking and ease of implementation. In this paper, the neural estimator has been studied with conventional and proposed learning algorithms. The sensitivity of the rotor resistance change has been tested for a wide range of variation from −50% to +50% on the stability of the drive system with and without estimator. It is quiet appealing to settle with optimal estimation time and error for the viable realization. The study is conducted extensively for estimation and tracking. The proposed learning algorithm is found to exhibit good estimation and tracking capabilities. Besides, it reduces computational complexity and, hence, more feasible for practical digital implementation.

Description: The standalone hybrid power system constitutes a synchronous generator driven by a diesel engine, renewable energy source (wind) apart from a battery energy storage system. A coherent control strategy to regulate the voltage and frequency of the standalone grid is proposed in this paper. The system is simulated using Matlab/Simulink for preliminary validation and further tested on a laboratory prototype which involves a TMS320LF2407A DSP controller to digitally implement the control strategy. The dynamic behavior of the system is perused through the direct connection of an induction machine. The control strategy is verified for step changes in load and variation in wind power.

Description: The thermal behavior of Nannochloropsis oculata combustion in air atmosphere were investigated by performing experiments on STA PT1600 Thermal Analyzer at heating rates of 10°C/min, 40°C/min and 70°C/min and range of temperatures from room temperature to 1200°C. The kinetic parameters were evaluated by using Kissinger and Ozawa methods. The result showed that Nannochloropsis oculata combustion occurred in five stages. Started with initial devolatilization, the main thermal decomposition and combustion process, transition stage, the combustion of char and the last stage was the slow burning reaction of residual char. In line with increasing heating rate, the mass loss rate increased as well, but it delayed the thermal decomposition processes toward higher temperatures. The average activation energy at the main thermal decomposition stage and the stage of char combustion were approximately 251 kJ/mol and 178 kJ/mol, respectively.

Description: Understanding the spatial variability of household carbon emissions is necessary for formulating sustainable and low-carbon energy policy. However, data on household carbon emissions is limited in China, the world’s largest greenhouse gases emitter. This study quantifies and maps household carbon emissions in Shanghai using a city-wide household survey. The findings reveal substantial spatial variability in household carbon emissions, especially in transport-related emissions. Low emission clusters are founded in Hongkou, Xuhui, Luwan, Jinshan, and Fengxian. High emission clusters are located in Jiading and Pudong. Overall, the spatial pattern of household carbon emissions in Shanghai is donut-shaped: lowest in the urban core, increasing in the surrounding suburban areas, and declining again in the urban fringe and rural regions. The household emissions are correlated with a number of housing and socioeconomic factors, including car ownership, type of dwelling, size of dwelling, age of dwelling, and income. The findings underscore the importance of a localized approach to low-carbon policymaking and implementation.

Description: The number of electric vehicles are increasing in the society as they are considered as zero emission vehicles and also because conventional fuels are becoming expensive. Additional electrical power should be produced to meet the energy requirement of this increase in electric vehicle population. To use the existing grid infrastructure without any failure, installing distributed generator at secondary distribution network is essential. In this work, sizing of wind-driven permanent magnet synchronous generator—photovoltaic hybrid distributed generating system has been attempted to meet the energy demand of electric vehicles of a particular residential area. Different feasible combinations for wind generator capacity and photovoltaic capacity are obtained to satisfy the additional energy requirement. Results are analyzed based on energy, financial payback periods and daily power profile of the hybrid system. Based on this analysis, the sizes of wind generator and photovoltaic array have been chosen to meet the energy demand of electric vehicles of that particular residential locality.

Description: Power system planning is a capital intensive investment-decision problem. The majority of the conventional planning conducted since the last half a century has been based on the least cost approach, keeping in view the optimization of cost and reliability of power supply. Recently, renewable energy sources have found a niche in power system planning owing to concerns arising from fast depletion of fossil fuels, fuel price volatility as well as global climatic changes. Thus, power system planning is under-going a paradigm shift to incorporate such recent technologies. This paper assesses the impact of renewable sources using the portfolio theory to incorporate the effects of fuel price volatility as well as CO 2 emissions. An optimization framework using a robust multi-objective evolutionary algorithm, namely NSGA-II, is developed to obtain Pareto optimal solutions. The performance of the proposed approach is assessed and illustrated using the Indian power system considering real-time design practices. The case study for Indian power system validates the efficacy of the proposed methodology as developing countries are also increasing the investment in green energy to increase awareness about clean energy technologies.

Description: Gas market in Europe is experiencing a radical change for different reasons, partially determined and accelerated by economic downturn of the last period. In the past few years, many European countries adopted energy policies largely based on the utilization of natural gas. In fact, a sharp increase of the demand was observed and, at the same time, a lot of infrastructures were developed to assure the necessary supply. In the last few years, due to the economic downturn, natural gas demand decreased, causing a consistent oversupply on the market, which altered the consolidated dynamics of the sector. Understanding the changes currently under development in the European gas market is of paramount importance in order to design future strategies for the sector; in particular, it is necessary to understand if the present situation will cause a reshaping of the sector.

Description: The aim of this paper is to investigate the implementation of a molten carbonate fuel cell (MCFC) as a CO 2 separator. By applying multi-objective optimization (MOO) using the genetic algorithm, the optimal values of operating load and the corresponding values of objective functions are obtained. Objective functions are minimization of the cost of electricity (COE) and minimization of CO 2 emission rate. CO 2 tax that is accounted as the pollution-related cost, transforming the environmental objective to the cost function. The results show that the MCFC stack which is fed by the syngas and gas turbine exhaust, not only reduces CO 2 emission rate, but also produces electricity and reduces environmental cost of the system.

Description: Due to the high interest in renewable energy and diversity of research regarding photovoltaic (PV) array, a great research effort is focusing nowadays on solar power generation and its performance improvement under various weather conditions. In this paper, an integrated framework was proposed, which achieved both maximum power point tracking (MPPT) and minimum ripple signals. The proposed control scheme was based on extremum-seeking (ES) combined with fractional order systems (FOS). This auto-tuning strategy was developed to maximize the PV panel output power through the regulation of the voltage input to the DC/DC converter in order to lead the PV system steady-state to a stable oscillation behavior around the maximum power point (MPP). It is shown that fractional order operators can improve the plant dynamics with respect to time response and disturbance rejection. The effectiveness of the proposed controller scheme is illustrated with simulations using measured solar radiation data.

Description: The operation condition of the cold-end system of a steam turbine has a direct impact on the economy and security of the unit as it is an indispensible auxiliary system of the thermal power unit. Many factors influence the cold-end operation of a steam turbine; therefore, the operation mode needs to be optimized. The optimization analysis of a 1000MW ultra-supercritical (USC) unit, the turbine cold-end system, was performed utilizing the back propagation (BP) neural network method with genetic algorithm (GA) optimization analysis. The optimized condenser pressure under different conditions was obtained, and it turned out that the optimized parameters were of significance to the performance and economic operation of the system.

Description: Hydrogen (H 2 ) is being considered as a primary automotive fuel and as a replacement for conventional fuels. Some of the desirable properties, like high flame velocity, high calorific value motivate us to use hydrogen fuel as a dual fuel mode in diesel engine. In this experiment, hydrogen was inducted in the inlet manifold with intake air. The experiments were conducted on a four stroke, single cylinder, water cooled, direct injection (DI), diesel engine at a speed of 1500 r/min. Hydrogen was stored in a high pressure cylinder and supplied to the inlet manifold through a water-and-air-based flame arrestor. A pressure regulator was used to reduce the cylinder pressure from 140 bar to 2 bar. The hydrogen was inducted with a volume flow rate of 4l pm, 6l pm and 8l pm, respectively by a digital volume flow meter. The engine performance, emission and combustion parameters were analyzed at various flow rates of hydrogen and compared with diesel fuel operation. The brake thermal efficiency (BTE) was increased and brake specific fuel consumption (BSFC) decreased for the hydrogen flow rate of 8l pm as compared to the diesel and lower volume flow rates of hydrogen. The hydrocarbon (HC) and carbon monoxide (CO) were decreased and the oxides of nitrogen (NO x ) increased for higher volume flow rates of hydrogen compared to diesel and lower volume flow rates of hydrogen. The heat release rate and cylinder pressure was increased for higher volume flow rates of hydrogen compared to diesel and lower volume flow rates of hydrogen.

Description:    Induction motor driven by vector control method makes high performance control of torque and speed possible. The decoupling of flux and electromagnetic torque obtained by field orientation depends on the precision and the accuracy of the estimated states. Rotor asymmetries lead to perturbations of air gap flux patterns in induction machines. These perturbations in flux components affect the electromagnetic torque, as well as stator currents and voltages. This paper first investigates the control of the induction motor using an extended Kalman filter (EKF) for a direct field-oriented control. It then studies the broken rotor bars (BRBs) fault by the monitoring the rotor resistance. The hypothesis on which the detection is based is that the apparent rotor resistance of the motor will increase when a rotor bar breaks. The rotor resistance is estimated and compared with its nominal value to detect BRBs fault. The EKF estimates the rotor flux, speed and rotor resistance on line by using only measurements of the stator voltages and currents. Simulation results show the effectiveness of the proposed method in the cases of load torque perturbation and speed reversion. Content Type Journal Article Category Research Article Pages 1-7 DOI 10.1007/s11708-012-0192-z Authors K. Yahia, GEB Laboratory, Department of Electrical Engineering, University of Biskra, BP 145, Biskra, Algeria S. Zouzou, GEB Laboratory, Department of Electrical Engineering, University of Biskra, BP 145, Biskra, Algeria F. Benchabane, MSE Laboratory, Department of Electrical Engineering, University of Biskra, BP 145, Biskra, Algeria Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701

Description:    An energy audit of 22 tertiary hospitals was conducted in Tianjin. The detailed content included design data, basic information, energy bills and equipment lists. It was shown that during the study, the energy intensity of hospitals in Tianjin was approximately stable and the average level of energy consumption was 348 kW·h/(m 2 ·a). From the date collected, it was calculated that the energy intensity of general hospitals was 380 kW·h/(m 2 ·a), and the average carbon emissions was 157 kgCO 2 /(m 2 ·a); While the energy intensity of specialized hospitals was 309 kW·h/(m 2 ·a), and the average carbon emissions was 131 kgCO 2 /(m 2 ·a). By breaking the energy consumption down into several items, it was found that the heating system consumed the highest amount of energy (42.12%), followed by the cooling system (6.78%), the medical equipment (4.98%) and the lighting system (3.63%). The main factors that affect the hospital energy consumption were determined, and some feasible technology and management measures to save energy and reduce carbon emissions were proposed. Content Type Journal Article Category Research Article Pages 1-9 DOI 10.1007/s11708-012-0199-5 Authors Chongxu Jiang, School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072 China Jincheng Xing, School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072 China Jihong Ling, School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072 China Xiaona Qin, School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701

Description:    This paper presents studies of spray characteristics and controlling mechanism of fuel containing CO 2 . Using diesel fuel containing CO 2 gas, experiments were conducted on diesel hole-type nozzles and simple nozzles. The steady spray and transient spray characteristics were observed and measured by instantaneous shadowgraphy, high-speed photography, phase Doppler anemometry (PDA) and LDSA respectively. The effects of CO 2 concentration in the fuel, the injection pressure, the nozzle L/D ratio, surrounding gas pressure and temperature on the atomization behavior and spray pattern were evaluated. The results show that the injection of fuel containing CO 2 can greatly improve the atomization and produce a parabolic-shaped spray; and the CO 2 gas concentration, surrounding gas pressure, temperature and nozzle configuration have dominant influences on spray characteristics of the fuel containing CO 2 . New insight into the controlling mechanism of atomization of the fuel containing CO 2 was provided. Content Type Journal Article Category Research Article Pages 80-88 DOI 10.1007/s11708-012-0180-3 Authors Zhen Huang, Key Laboratory for Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240 China Jin Xiao, Key Laboratory for Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240 China Xinqi Qiao, Key Laboratory for Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240 China Gaozhi Jiang, Faculty of Science and Engineering, Waseda University, Tokyo, 169-8555 Japan Yiming Shao, Faculty of Transportation Engineering, Chongqing Jiaotong University, Chongqing, 400074 China Seiichi Shiga, Faculty of Engineering, Department of Mechanical System Engineering, Gunma University, Gunma, 376-8515 Japan Yasuhiro Daisho, Faculty of Science and Engineering, Waseda University, Tokyo, 169-8555 Japan Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 6 Journal Issue Volume 6, Number 1

Description:    This paper discusses two problems in in-line particle sizing when using light fluctuation method. First, by retrieving the ratio of particle concentrations at different time, the intensity of incident light is obtained. There exists narrow error between the calculated and pre-detected value of the intensity of incident light. Secondly, by combining spectrum analysis with Gregory’s theory, a multi-sub-size zone model is proposed, with which the relationship between the distribution of turbidity and the particle size distribution (PSD) can be established, and an algorithm developed to determine the distribution of turbidity. Experiments conducted in the laboratory indicate that the measured size distribution of pulverized coal conforms well with the imaging result. Content Type Journal Article Category Research Article Pages 89-97 DOI 10.1007/s11708-012-0176-z Authors Shouxuan Qin, Institute of Particle and Two-phase Flow Measurement, University of Shanghai for Science & Technology, Shanghai, 200093 China Xiaoshu Cai, Institute of Particle and Two-phase Flow Measurement, University of Shanghai for Science & Technology, Shanghai, 200093 China Li Ma, Institute of Particle and Two-phase Flow Measurement, University of Shanghai for Science & Technology, Shanghai, 200093 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 6 Journal Issue Volume 6, Number 1

Description:    An optically accessed, single cylinder engine operated in homogenous charge compression ignition (HCCI) mode with negative valve overlap (NVO) strategy was used to perform combustion processes diagnostics under premixed conditions corresponding to the low load regime of the HCCI operational envelope. The aforementioned processes analysis was conducted utilizing synchronized simultaneous combustion event crank-angle resolved images, acquired through piston crown window with in-cylinder pressure recording. This investigation was carried out for one-step ignition fuel—standard gasoline, fuel proceeding single-stage ignition process under conditions studied. The initial combustion stage is characterized by a maximum local reaction spreading velocity in the range of 40–55 m/s. The later combustion stage reveals values as high as 140 m/s in case of stoichiometric combustion. The mixture as well as combustion stages effects are pronounced in these observed analytical results. Content Type Journal Article Category Reseach Article Pages 313-321 DOI 10.1007/s11708-011-0154-x Authors Pawel Luszcz, School of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT UK Hongming Xu, Department of Automotive Engineering, Tsinghua University, Beijing, 100084 China Mirek Wyzsnski, School of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT UK Xiao Ma, Department of Automotive Engineering, Tsinghua University, Beijing, 100084 China Rob Stevens, Jaguar and Land Rover Research, Coventry, CV3 4LF UK Athanasios Tsolakis, School of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT UK Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 3

Description:    To investigate the performance of heat and mass transfer of ammonia-water during the process of falling film evaporation in vertical tube evaporator, a mathematical model of evaporation process was presented, the solution of which that needed a coordinate transformation was based on stream function. The computational results from the mathematical model were validated with experimental data. Subsequently, a series of parameters, such as velocity, film thickness and concentration, etc., were obtained from the mathematical model. Calculated results show that the average velocity and the film thickness change dramatically at the entrance region when x 〈100 mm, while they vary slightly with the tube length in the fully developed region when x 〉100 mm. The average concentration of the solution reduces along the tube length because of evaporation, but the reducing tendency becomes slow. It can be concluded that there is an optimal relationship between the tube length and the electricity generated. The reason for the bigger concentration gradient in the y direction is that the smooth tube is chosen in the calculation. It is suggested that the roll-worked enhanced tube or other enhanced tube can reduce the concentration gradient in the film thickness direction and enhance the heat and mass transfer rate. Content Type Journal Article Category Research Article Pages 358-366 DOI 10.1007/s11708-011-0161-y Authors Xianbiao Bu, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou, 510640 China Weibin Ma, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou, 510640 China Huashan Li, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou, 510640 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 4

Description:    Natural gas (NG) represents today a promising alternative to conventional fuels for road vehicles propulsion, since it is characterized by a relatively low cost, better geopolitical distribution than oil, and lower environmental impact. This explains the current spreading of compressed natural gas (CNG) fuelled spark ignition (SI) engine, above all in the bi-fuel version, which is able to run either with gasoline or with NG. However, the aim of the present investigation is to evaluate the emission characteristics at idling condition. The vehicle engine was converted to bifueling system from a gasoline engine, and operated separately either with gasoline or CNG. Two different fuel injection systems (i.e., multi-point injection (MPI)-sequential and closed-loop venturi-continuous) are used, and their influences on the formation of emissions at different operating conditions are examined. A detailed comparative analysis of the engine exhaust emissions using gasoline and CNG is made. The results indicate that the CNG shows low air index and lower emissions of carbon monoxide (CO), carbon dioxide (CO 2 ), and total hydrocarbon (THC) compared to gasoline. Content Type Journal Article Category Reseach Article Pages 322-329 DOI 10.1007/s11708-011-0158-6 Authors Sameh M. Metwalley, Faculty of Engineering, Helwan University, Cairo, Egypt Shawki A. Abouel-Seoud, Faculty of Engineering, Helwan University, Cairo, Egypt Abdelfattah M. Farahat, Faculty of Engineering, Helwan University, Cairo, Egypt Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 3

Description:    As a result of adopting saturation steam and long blade, problems of water erosion of last stage blade for steam turbine become more prominent. In order to improve the operation reliability and efficiency of steam turbine, it is necessary to investigate the nonequilibrium condensing wet steam two phase flow and the dehumidity method. A wet steam model with user defined function based on FLUENT software was investigated to simulate the steam condensing flow in the cascades. The simulation consequences show that the pressure variations in simulation depict a good agreement with the experiment data. On the basis of the discrete phase model simulation results and experiment data, the efficiency of existing dehumidity blade with suction slot was calculated. A new stationary dehumidity blade was designed to elevate the dehumidity efficiency: the efficiency in the suction surface was increased by 21.5%, and that in the pressure surface was increased by 12.2%. Content Type Journal Article Category Research Article Pages 288-296 DOI 10.1007/s11708-011-0160-z Authors Youmin Hou, School of Power and Mechanical Engineering, Wuhan University, Wuhan, 430072 China Danmei Xie, School of Power and Mechanical Engineering, Wuhan University, Wuhan, 430072 China Wangfan Li, Shanghai Power Equipment Research Institute, Shanghai, 200240 China Xinggang Yu, School of Power and Mechanical Engineering, Wuhan University, Wuhan, 430072 China Yang Shi, School of Power and Mechanical Engineering, Wuhan University, Wuhan, 430072 China Hanshi Qin, School of Power and Mechanical Engineering, Wuhan University, Wuhan, 430072 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 3

Description:    Pure Fe, Cr, Al, Ti elemental powders and prealloyed Y 2 O 3 powder were processed by high energy mechanical milling. The compositions of the mixed powders are designed as Fe-18Cr-0.2Ti-0.35Y 2 O 3 and Fe-18Cr-5Al-0.2Ti-0.35Y 2 O 3 in weight percent. The asmilled powders were consolidated by hot extrusion at 1423 K. The dispersed oxide particles were identified to be titania + yttria for Al-free oxide dispersion strengthened (ODS) steel and alumina + yttria for Al-added ODS steel, respectively. The ultimate tensile strength of Al-free ODS steel was higher than that of Al-added ODS steel over the temperature range of 298–973 K, because of the difference in number density and size of thermally stable oxide particles dispersed in both steel matrices. The strength in the longitudinal direction was lower than that in the transverse direction, probably due to anisotropy of the microstructure with elongated grains in the hot-extrusion direction for the 18%Cr-ODS steels with and without 5% Al. Content Type Journal Article Category Research Article Pages 29-34 DOI 10.1007/s11708-012-0178-x Authors Jae Hoon Lee, Sheet Products & Process Research Gr., POSCO Technical Research Laboratories, 699, Gumho-dong, Gwangyang-si, Jeonnam, 545-090 Republic of Korea Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 6 Journal Issue Volume 6, Number 1

Description:    This paper presents an approach for the structural modeling and analysis of a typical gas turbine system. This approach has been applied to the systems and subsystems, which are integral parts of a typical gas turbine system. Since a gas turbine system performance is measured in terms of fluid flow energy transformations across its various assemblies and subassemblies, the performance of such subsystems affects the overall performance of the gas turbine system. An attempt has been made to correlate the associativity of such subsystems contributing to overall gas turbine system functional evaluation using graph theoretic approach. The characteristic equations at the system level as well as subsystem level have been developed on the basis of associativity of various factors affecting their performance. A permanent function has been proposed for the functional model of a gas turbine system, which further leads to selection, identification and optimal evaluation of gas turbine systems. Content Type Journal Article Category Research Article Pages 57-79 DOI 10.1007/s11708-011-0164-8 Authors Naresh Yadav, Mechanical Engineering Department, Jamia Millia Islamia, New Delhi, 110025 India Irshad Ahmad Khan, Mechanical Engineering Department, Jamia Millia Islamia, New Delhi, 110025 India Sandeep Grover, Mechanical Engineering Department, YMCA University of Science and Technology, Faridabad, 121006 India Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 6 Journal Issue Volume 6, Number 1

Description:    Surface nitrogen complex formation upon reaction of coal char with NO at 600°C was studied by X-ray photoelectron spectroscopy. Particle size had a noticeable effect on the magnitude of changes, which was observed on the surface of the coal char in the nitrogen functional group. The surface increased its -NO, pyridine-N-oxide, and -NO 2 functional group contents with a decrease in particle size. The chemisorption processes of NO molecules on the char were simulated using the ab initio Hartree-Fock method and density functional theory. Molecular modeling was applied to determine the thermodynamics of the reactions. Mechanisms were proposed to explain the formation of the -NO, pyridine-N-oxide, and -NO 2 functional groups at 600°C. Content Type Journal Article Category Research Article Pages 221-228 DOI 10.1007/s11708-011-0146-x Authors Xiumin Jiang, Institute of Thermal Energy Engineering, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240 China Xiangyong Huang, Institute of Thermal Energy Engineering, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240 China Jiaxun Liu, Institute of Thermal Energy Engineering, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240 China Chaoqun Zhang, Institute of Thermal Energy Engineering, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 2

Description:    Current work on the performance of a solid oxide fuel cell (SOFC) and gas turbine hybrid system is presented. Each component model developed and applied is mathematically defined. The electrochemical performance of single SOFC with different fuels is tested. Experimental results are used to validate the SOFC mathematical model. Based on the simulation model, a safe operation regime of the hybrid system is accurately plotted first. Three different part-load strategies are introduced and used to analyze the part-load performance of the hybrid system using the safe regime. Another major objective of this paper is to introduce a suitable startup and shutdown strategy for the hybrid system. The sequences for the startup and shutdown are proposed in detail, and the system responses are acquired with the simulation model. Hydrogen is used instead of methane during the startup and shutdown process. Thus, the supply of externally generated steam is not needed for the reforming reaction. The gas turbine is driven by complementary fuel and supplies compressed air to heat up or cool down the SOFC stack operating temperature. The dynamic simulation results show that smooth cooling and heating of the cell stack can be accomplished without external electrical power. Content Type Journal Article Category Research Article Pages 181-194 DOI 10.1007/s11708-011-0149-7 Authors Yang Li, School of Mechanical Engineering, Key Laboratory for Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240 China Yiwu Weng, School of Mechanical Engineering, Key Laboratory for Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240 China Shilie Weng, School of Mechanical Engineering, Key Laboratory for Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 2

Description:    A fully three-dimensional mathematical model of a planar solid oxide fuel cell (SOFC) with complete direct internal steam reforming was constructed to investigate the chemical and electrochemical characteristics of the porous-electrode-supported (PES)-SOFC developed by the Central Research Institute of Electric Power Industry of Japan. The effective kinetic models developed over the Ni/YSZ anode takes into account the heat transfer and species diffusion limitations in this porous anode. The models were used to simulate the methane steam reforming processes at the co- and counter-flow patterns. The results show that the flow patterns of gas and air have certain effects on cell performance. The cell at the counter-flow has a higher output voltage and output power density at the same operating conditions. At the counter-flow, however, a high hotspot temperature is observed in the anode with a non-fixed position, even when the air inlet flow rate is increased. This is disadvantageous to the cell. Both cell voltage and power density decrease with increased air flow rate. Content Type Journal Article Category Research Article Pages 195-206 DOI 10.1007/s11708-011-0148-8 Authors Yuzhang Wang, School of Mechanical Engineering, Key Laboratory for Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240 China Shilie Weng, School of Mechanical Engineering, Key Laboratory for Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240 China Yiwu Weng, School of Mechanical Engineering, Key Laboratory for Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 2

Description:    A surge in interest in developing alternative renewable energy technologies has been observed in recent years. In particular, thermoelectrics has drawn attention because thermoelectric effects enable direct conversion between thermal and electrical energy, and provide power generation and refrigeration alternatives. During the past decade, the performance of thermoelectric materials has been considerably improved; however, many challenges continue to exist. Developing thermoelectric materials with superior performance means tailoring interconnected thermoelectric physical parameters-electrical conductivities, Seebeck coefficients, and thermal conductivities for a crystalline system. The objectives of this paper are to introduce the recent developments in semiconductor thermoelectric materials, and briefly summarize the applications of such materials. Content Type Journal Article Category Feature Article Pages 125-136 DOI 10.1007/s11708-011-0150-1 Authors Laifeng Li, The Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 China Zhen Chen, The Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 China Min Zhou, The Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 China Rongjin Huang, The Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 2

Description:    In this paper, the feasibility of using metal foams to enhance the heat transfer capability of phase change materials (PCMs) in low- and high-temperature thermal energy storage systems was assessed. Heat transfer in solid/liquid phase change of porous materials (metal foams and expanded graphite) at low and high temperatures was investigated. Organic commercial paraffin wax and inorganic calcium chloride hydrate were employed as the low-temperature materials, whereas sodium nitrate was used as the high-temperature material in the experiment. Heat transfer characteristics of these PCMs embedded with open-cell metal foams were studied. Composites of paraffin and expanded graphite with a graphite mass ratio of 3%, 6%, and 9% were developed. The heat transfer performances of these composites were tested and compared with metal foams. The results indicate that metal foams have better heat transfer performance due to their continuous inter-connected structures than expanded graphite. However, porous materials can suppress the effects of natural convection in liquid zone, particularly for PCMs with low viscosities, thereby leading to different heat transfer performances at different regimes (solid, solid/liquid, and liquid regions). This implies that porous materials do not always enhance heat transfer in every regime. Content Type Journal Article Category Research Article Pages 174-180 DOI 10.1007/s11708-011-0140-3 Authors C. Y. Zhao, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240 China D. Zhou, School of Engineering, University of Warwick, Coventry, UK Z. G. Wu, School of Engineering, University of Warwick, Coventry, UK Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 2

Description:    Permeability and thermal conductivity test units were set up to study the heat and mass transfer performance of the host material, i.e. expanded natural graphite (ENG), for consolidated activated carbon (AC) adsorbent. The permeability was tested with nitrogen as the gas source, and the thermal conductivity was studied using steady-state heat source method. The results showed that the values of permeability and thermal conductivity were 10 −15 to 10 −12 m 2 and 1.7 to 3.2 W/(m·K), respectively, while the density compressed expanded natural graphite (CENG) varied from 100 to 500 kg/m 3 . The permeability decreased with the increasing density of CENG, whereas the thermal conductivity increased with the increasing density of CENG. Then the thermal conductivity and permeability of granular AC were researched. It was discovered that the thermal conductivity of samples with different grain size almost kept constant at 0.36 W/(m·K) while the density was approximately 600 kg/m 3 . This means that the thermal conductivity was not related to the grain size of AC. The thermal conductivity of CENG was improved by 5 to 10 times compared with that of granular AC. Such a result showed that CENG was a promising host material for AC to improve the heat transfer performance, while the mass transfer performance should be considered in different conditions for utilization of adsorbent. Content Type Journal Article Category Research Article Pages 159-165 DOI 10.1007/s11708-011-0145-y Authors Bo Tian, Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai, 200240 China Liwei Wang, Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai, 200240 China Zhequan Jin, Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai, 200240 China Ruzhu Wang, Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai, 200240 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 2

Description:    Most people were not aware of the role of energy as a basic force that drives the development and economic growth of the world until the two great oil crises occurred. According to the conservation law, energy not only exists in various forms but is also capable of being converted from one form to another. The common forms of energy are mechanical energy, chemical energy, internal energy, electrical energy, atomic energy, and electromagnetic energy, among others. The fluids in nature serve as the most common carriers and media in the energy conversion process. Following the rapid development of microelectromechanical systems (MEMS) technology, the energy supply and conversion issue in micro/nano scale has also been introduced in research laboratories worldwide. With unremitting efforts, great quantities of micro/nano scale energy devices have been investigated. Micro/nanofluid shows distinct features in transporting and converting energy similar to their counterpart macroscale tasks. In this paper, a series of micro/nanofluid-enabled energy conversion devices is reviewed based on the transformation between different forms of energy. The evaluation and contradistinction of their performances are also examined. The role of micro/nanofluid as media in micro/nano energy devices is summarized. This contributes to the establishment of a comprehensive and systematic structure in the relationship between energy conversion and fluid in the micro/nano scale. Some fundamental and practical issues are outlined, and the prospects in this challenging area are explored. Content Type Journal Article Category Review Article Pages 270-287 DOI 10.1007/s11708-010-0126-6 Authors Yang Yang, Key Laboratory of Cryogenics (Y0AS011010), Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 China Jing Liu, Key Laboratory of Cryogenics (Y0AS011010), Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 3

Description:    Aeroelasticity has become a critical issue for Multi-Megawatt wind turbine due to the longer and more flexible blade. In this paper, the development of aeroelasticity and aeroelastic codes for wind turbine is reviewed and the aeroelastic models for wind turbine blade are described, based on which, the current research focuses for large scale wind turbine are discussed, including instability problems for onshore and offshore wind turbines, effects of complex inflow, nonlinear effects of large blade deflection, smart structure technologies, and aerohydroelasticity. Finally, the future development of aeroelastic code for large scale wind turbine: aeroservoelasticity and smart rotor control; nonlinear aeroelasticity due to large blade deflection; full-scale 3D computational fluid dynamics (CFD) solution for dynamics; and aerohydroelasticity are presented. Content Type Journal Article Category Review Article Pages 419-434 DOI 10.1007/s11708-011-0166-6 Authors Pinting Zhang, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, 430074 China Shuhong Huang, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, 430074 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 4

Description:    The flow structure in tight lattice is still of great interest to nuclear industry. An accurate prediction of flow parameter in subchannels of tight lattice is likable. Unsteady Reynolds averaged Navier Stokes (URANS) is a promising approach to achieve this goal. The implementation of URANS approach will be validated by comparing computational results with the experimental data of Krauss. In this paper, the turbulent flow with different Reynolds number (5000–215000) and different pitch-to-diameter( P/D ) (1.005–1.2) are simulated with computational fluid dynamics (CFD) code CFX12. The effects of the Reynolds number and the bundle geometry ( P/D ) on wall shear stress, turbulent kinetic energy, turbulent mixing and large scale coherent structure in tight lattice are analyzed in details. It is hoped that the present work will contribute to the understanding of these important flow phenomena and facilitate the prediction and design of rod bundles. Content Type Journal Article Category Research Article Pages 404-411 DOI 10.1007/s11708-011-0165-7 Authors Yiqi Yu, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240 China Yanhua Yang, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 4

Description:    In this paper, the effect of cetane number (CN) improver on performance and emissions, including particulate number concentration and size distribution, of a turbocharged, common-rail diesel engine fueled with biodiesel-methanol were studied. Two volume fractions (0.3% and 0.6%) of CN improver were added to BM30 (30% of methanol in the biodiesel-methanol blend) in the experiment. The results show that, compared with those of biodiesel-methanol blend, the peak value of cylinder pressure increases, the second peak of heat release rate decreases, the start of second heat release are advanced, and the fuel economy and thermal efficiency are improved when CN improver is added to biodiesel-methanol blend. Besides, CO and HC emissions decrease, NO x emission varies little and smoke emissions increase slightly. Moreover, exhaust particles of BM30 mainly distribute in nanosize range. Furthermore, particle number concentration decreases and peak of size distribution profile shifts toward large size direction. Content Type Journal Article Category Research Article Pages 412-418 DOI 10.1007/s11708-011-0163-9 Authors Wu Yu, State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 China Gen Chen, State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 China Huang Zuohua, State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 4

Description:    The simulation model of a power generation system was developed based on EASY5 simulation platform. The performances of the power plant under the conditions of the furnace slagging and ash deposition of the heating surfaces in the boiler were simulated. The results show that the simulation model can reasonably reflect the characteristics of the power plant when each component is under fault conditions. Through fault simulation, the change of the performance parameters can be obtained, which can be used in fault diagnosis system as the diagnosis criterion for expert system. Content Type Journal Article Pages 435-443 DOI 10.1007/s11708-011-0162-x Authors Weiwei Zhang, The Key Laboratory of Power Machinery and Engineering of the Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200030 China Huisheng Zhang, The Key Laboratory of Power Machinery and Engineering of the Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200030 China Ming Su, The Key Laboratory of Power Machinery and Engineering of the Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200030 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 4

Description:    Water is perhaps the most widely adopted working fluid in conventional industrial heat transport engineering. However, it may no longer be the best option today due to the increasing scarcity of water resources. Furthermore, the wide variations in water supply throughout the year and across different geographic regions also makes it harder to easily access. To address this issue, finding new alternatives to replace water-based technologies is imperative. In this paper, the concept of a water-free heat exchanger is proposed and comprehensively analyzed for the first time. The liquid metal with a low melting point is identified as an ideal fluid that can flexibly be used within a wide range of working temperatures. Some liquid metals and their alloys, which have previously received little attention in thermal management areas, are evaluated. With superior thermal conductivity, electromagnetic field drivability, and extremely low power consumption, liquid metal coolants promise many opportunities for revolutionizing modern heat transport processes: serving as heat transport fluid in industries, administrating thermal management in power and energy systems, and innovating enhanced cooling in electronic or optical devices. Furthermore, comparative analyses are conducted to understand the technical barriers encountered by advanced water-based heat transfer strategies and clarify this new frontier in heat-transport study. In addition, the unique merits of liquid metals that could lead to innovative heat exchanger technologies are evaluated comprehensively. A few promising industrial situations, such as heat recovery, chip cooling, thermoelectricity generation, and military applications, where liquid metals could play irreplaceable roles, were outlined. The technical challenges and scientific issues thus raised are summarized. With their evident ability to meet various critical requirements in modern advanced energy and power industries, liquid metal-enabled technologies are expected to usher a new and global era of water-free heat exchangers. Content Type Journal Article Category Feature Article Pages 20-42 DOI 10.1007/s11708-011-0139-9 Authors Haiyan Li, Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Bejing, 100190 China Jing Liu, Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Bejing, 100190 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 1

Description:    In China, coal is a dominant component of energy mix, and it is expected to remain as such over the next 30 to 40 years. Coal is expected to be used even more in power generation. The direct combustion of coal already has been causing severe pollution and ecological degradation, and it is quite difficult to address the need to reduce greenhouse gas (GHG) given the direct combustion of coal. Therefore, the polygeneration system based on coal gasification, which is one of the major examples of synergistic utilization of coal, is proposed. It is a comprehensive solution to meet the energy challenges China is facing. Furthermore, the synergy of fossil fuels (especially coal) with renewable energy, the synergy of different kinds of energy for energy storage, the synergy of centralized and distributed supply of different kinds of energy, and the synergy of different kinds of energy in smart energy grid (power, gas, heat, and water) are the keys to making China a low-carbon economy. Carbon dioxide (CO 2 ) mitigation in China should begin from the coalchemical industry given their accumulated relevant experiences. The mitigation process should gradually be transformed into the “IGCC + polygeneration + CCUS”. The objectives of this paper are to describe the synergistic utilization of coal, and to analyze the synergy of coal with other energy resources, and to propose the scientific and technological problems to achieve these synergies. Content Type Journal Article Category Feature Article Pages 1-19 DOI 10.1007/s11708-010-0136-4 Authors Weidou Ni, State Key Laboratory of Control and Simulation of Power System and Generation Equipment, Department of Thermal Engineering, Tsinghua University, Beijing, 100084 China Zhen Chen, State Key Laboratory of Control and Simulation of Power System and Generation Equipment, Department of Thermal Engineering, Tsinghua University, Beijing, 100084 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 1

Description:    Global warming poses serious global concerns, and the mobile air conditioning (MAC) industry must be promoted to reduce greenhouse gas emissions. In this paper, the development of the MAC system and components for new energy vehicles, low global warming potential (GWP) refrigerants, methods to control refrigerant leakage, and new energy-saving technologies in China are introduced. Content Type Journal Article Category Review Article Pages 53-58 DOI 10.1007/s11708-010-0137-3 Authors Jiangping Chen, Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai, 200240 China Yu Zhao, Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai, 200240 China Zhaogang Qi, Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai, 200240 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 1

Description:    The influence of energy intensity ɛ on carbon intensity κ depends upon the fraction of energy mixes with high carbon emissions in the total energy mixes γ . The correlation of γ with a variety of primary energy mix fractions and technology advances such as CCS and CCHP is analyzed and deduced. Taking the long-term carbon reduction target in 2050 settled upon by the Copenhagen Agreement and the mid-term target suggested by the “450 Scenes Program” of the International Energy Agency (IEA) as constraints, the new pattern of the energy transition of the world in 2020, 2030, and 2050 are estimated and figured out. The peak value of energy consumption will lag behind the peak value of carbon emissions; the world energy structure shifting point will be in 2020–2025. Estimates show that China’s mid-2020 and long-term targets of energy-saving and emission reduction announced by the Chinese government might be achieved. Content Type Journal Article Category Research Article Pages 214-220 DOI 10.1007/s11708-010-0133-7 Authors Ben Hua, Research Center of Natural Gas, South China University of Technology, Guangzhou, 510640 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 2

Description:    The combustion and emission characteristics of a turbo-charged, common rail diesel engine fuelled with diesel-biodiesel-DEE blends were investigated. The study reports that the brake-specific fuel consumption of dieselbiodiesel-DEE blends increases with increase of oxygenated fuel fractions in the blends. Brake thermal efficiency shows little variation when operating on different dieselbiodiesel-DEE blends. At a low load, the NO x emission of the diesel-biodiesel-DEE blends exhibits little variation in comparison with the biodiesel fraction. The NO x emission slightly increases with increase in the biodiesel fraction in diesel-biodiesel-DEE blends at medium load. However, the NO x emission increases remarkably with increase of the biodiesel fraction at high load. Particle mass concentration decreases significantly with increase of the oxygenated-fuels fraction at all engine speeds and loads; particle number concentration decreases remarkably with increase of the oxygenated-fuels fraction. HC and CO emissions decrease with increasing oxygenated-fuels fraction in these blends. Content Type Journal Article Category Research Article Pages 104-114 DOI 10.1007/s11708-011-0138-x Authors Ni Zhang, State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 China Zuohua Huang, State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 China Xiangang Wang, State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 China Bin Zheng, State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 1

Description:    This paper aims to investigate the Granger causality relationships between the photovoltaic (PV) market scale and PV manufacturing development in China, Germany, the US, and Japan, and consequently provide recommendations for strategic investment and industrial policy making. The empirical results show that the growth of the market scale caused the increase in innovation scale in the four countries except China. Moreover, there were bidirectional causalities between them in Germany and in the US, respectively, suggesting that the strategic perspective and the formation of a virtuous circle could make PV industry policies cost effective. Only in China did the growth of the market scale cause the increase in production scale, implying significant market risk for the manufacturing sector. The empirical result shows that the manufacturing sector can affect the dynamics of the market scale. Content Type Journal Article Category Research Article Pages 43-48 DOI 10.1007/s11708-010-0135-5 Authors Molin Huo, Institute of Energy, Environment and Economy, Tsinghua University, Beijing, 100084 China Xiliang Zhang, Institute of Energy, Environment and Economy, Tsinghua University, Beijing, 100084 China Jiankun He, Institute of Low Carbon Economy, Tsinghua University, Beijing, 100084 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 1

Description:    Approximately 2.8 × 10 10 m 3 of methane is emitted per year to the atmosphere from coal mining activities around the world. Mitigation and utilization of the fugitive coal mine methane is very difficult because its concentration is very low and varies from 0.1% to 1%, and the methane is contained in a large air flow rate of 150–400 m 3 /s. This paper overviews existing and developing technologies for the mitigation and utilization of the fugitive mine methane, and then presents research progress in developing an innovative lean burn catalytic turbine technology for fugitive methane mitigation and utilization. This turbine system can be powered with about 1% methane in air. Content Type Journal Article Category Review Article Pages 229-235 DOI 10.1007/s11708-011-0147-9 Authors Shi Su, CSIRO Advanced Coal Technology, 1 Technology Court, Pullenvale, QLD 4069, Australia Xinxiang Yu, CSIRO Advanced Coal Technology, 1 Technology Court, Pullenvale, QLD 4069, Australia Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 2

Description:    A two-stage chemisorption cycle suitable for deep-freezing application driven by low-temperature heat source was proposed. Through two-stage desorption processes, the two-stage cycle can break through the limitations of the heating temperature and ambient cooling temperature. The two-stage cycle based on CaCl 2 /BaCl 2 -NH 3 working pair can utilize the heat source with a temperature of above 75°C, and simultaneously realize deep-freezing all the year round. Experimental results and performance prediction show that the adsorption quantity of calcium, theoretical coefficient of performance (COP) and optimized specific cooling power (SCP) of the CaCl 2 /BaCl 2 -NH 3 chemisorption system are 0.489 kg/kg (salt), 0.24 and 120.7W/kg, when the heating temperature, ambient cooling temperature, pseudo-evaporating temperature and mass ratio of reacting salt and expanded graphite are 85, 30, −20, and 4:1, respectively. Content Type Journal Article Category Research Article Pages 263-269 DOI 10.1007/s11708-011-0152-z Authors Yuanyang Hu, Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai, 200240 China Liwei Wang, Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai, 200240 China Lu Xu, Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai, 200240 China Ruzhu Wang, Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai, 200240 China Jeremiah Kiplagat, Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai, 200240 China Jian Wang, Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai, 200240 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 3

Description:    The analysis of collected wind data at two sites in the Gaza Strip, namely, Gaza City and Gaza International Airport in Rafah city, is presented. The two sites are candidates for remote area wind energy applications. The purpose of this paper is to present the results of the assessment of wind energy potential in the Gaza Strip in order to evaluate the wind regimes for installing wind energy conversion systems for power generation. The data on wind speed, direction and frequency distribution are used to analyze wind energy characteristics and availability at some stations in the Gaza Strip. The vertical extrapolation was based on the power-law expression, and the wind energy and potential have been estimated at the wind turbine hub height of approximately 50 m. Furthermore, the values of theWeibull parameters c and k are determined from summary statistics of wind resource. Consequently, the wind power is estimated by adoption of the Weibull distribution expression. Based on the results of this paper, sites are recommended for wind energy exploitation in the Gaza Strip. Content Type Journal Article Category Research Article Pages 297-304 DOI 10.1007/s11708-010-0134-6 Authors Juma Yousuf Alaydi, Industrial Engineering Department, IUG, Gaza, Palestine Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 3

Description:    An economic evaluation of a network of distributed energy resources (DERs) comprising a microgrid structure of power delivery system in an Indian scenario has been made. The mathematical analysis is based on the application of tuned genetic algorithm (TGA). The analyses for optimal power operation pertaining to minimum cost have been made for two cases in Indian power delivery system. The first case deals with the consumers’ individual optimal operation of DERs, while in the second one, consumers altogether form a microgrid with the optimal supply of power from DERs. The total annual costs for these two cases are found to be economically competitive and encouraging. A reduction of approximately 5.7% in the annual cost has been obtained in the case of microgid system than that in the separately operating consumers’ system for a small locality of India. It is observed that the application of TGA results in a reduction of the minimum cost depicting an improved outcome in terms of energy economy. Content Type Journal Article Category Research Article Pages 12-20 DOI 10.1007/s11708-012-0172-3 Authors Trina Som, Power Engineering Department, Jadavpur University, Kolkata, 700098 India Niladri Chakraborty, Power Engineering Department, Jadavpur University, Kolkata, 700098 India Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 6 Journal Issue Volume 6, Number 1

Description:    Solid oxide fuel cell (SOFC) is a complicated system with heat and mass transfer as well as electrochemical reactions. The flowing configuration of fuel and oxidants in the fuel cell will greatly affect the performance of the fuel cell stack. Based on the developed mathematical model of direct internal reforming SOFC, this paper established a distributed parameters simulation model for cocurrent and countercurrent types of SOFC based on the volume-resistance characteristic modeling method. The steady-state distribution characteristics and dynamic performances were compared and were analyzed for cocurrent and countercurrent types of SOFCs. The results indicate that the cocurrent configuration of SOFC is more suitable with regard to performance and safety. Content Type Journal Article Category Research Article Pages 207-213 DOI 10.1007/s11708-011-0151-0 Authors Huisheng Zhang, The Key Laboratory of Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240 China Shilie Weng, The Key Laboratory of Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240 China Ming Su, The Key Laboratory of Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240 China Journal Frontiers in Energy Online ISSN 2095-1698 Print ISSN 2095-1701 Journal Volume Volume 5 Journal Issue Volume 5, Number 2