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  • LUNAR AND PLANETARY EXPLORATION  (10)
  • Chemical Engineering  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Visualization of flow characteristics in a 2-D bubble column and three-phase fluidized bed (1993)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 39 (1993), S. 733-744 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Macroscopic flow structures of gas-liquid and gas-liquid-solid fluidization systems are studied through flow visualization using a two-dimensional column under various operating conditions. The gas distributor in the column comprises multiple injectors which are individually regulated to generate desired gas flow rates, bubble injection frequencies, and bubble sizes. Colored bed particles and neutrally buoyant particles as solid and liquid tracers, respectively, are used for flow visualization through video photography. In a gas-liquid system operated under liquid-batch conditions, bubble streams injected near both sidewalls are observed to migrate toward bed vertical axis, and vortices appear along the sidewalls when gas velocity exceeds 4-6 mm/s. A considerable amount of liquid descends along the sidewalls in a vortical flow pattern. The gross circulation pattern occurring at high gas velocities is associated closely with induced liquid or liquid-solid flows resulting from rising bubbles and bubble wakes. When the gross circulation occurs, four flow regions can be distinguished. The formation of and mechanism for gross circulations can be interpreted in part based on two simplified flow conditions involving single bubbles rising in a stationary liquid and single chains of bubbles injected in a batch liquid. The effects of particle size, inlet liquid velocity and gas flow distribution on the macroscopic flow structure are also examined.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690390502
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Flow structure in a three-dimensional bubble column and three-phase fluidized bed (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1093-1104 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Macroscopic flow structures of 3-D bubble columns and gas-liquid-solid fluidization systems under various operating conditions are studied using particle image velocimetry. Flow visualization is also conducted with the aid of a laser sheeting technique. The refractive index matching technique is used to eliminate the opaqueness of solid particles occurred in the visualization study of gas-liquid-solid fluidization. Three flow regimes (dispersed bubble, vortical-spiral flow, and turbulent flow) are identified. The flow structure is investigated for various operating variables including liquid velocity, gas velocity, and particle holdups. Four flow regions (descending flow, vortical-spiral flow, fast bubble flow, and central plume) can generally be characterized in the vortical-spiral flow regime where the gross circulation pattern occurs. A conceptual model for the flow structure in the vortical-spiral flow regime is discussed. The transition of the flow regimes and structure in the vortical-spiral flow regime is postulated to be related to the Taylor instability for flow between two concentric rotating cylinders. Similarities between the flow structures of 2- and 3-D beds are also discussed.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400702
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  • 3
    Electronic Resource
    Electronic Resource
    Compressible isothermal slip flow in the entrance region (1971)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 747-749 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690170347
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  • 4
    Electronic Resource
    Electronic Resource
    Prediction of the dew point locus in methane-light hydrocarbon binary systems in the neighborhood of the methane critical point (1974)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 399-401 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690200232
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  • 5
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    Time-dependent calculations of Jupiter's ionosphere (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Time-dependent calculations of the vertical distribution of protons in Jupiter's ionosphere show that the accumulation of protons in the topside ionosphere produced from solar ionizing radiation overwhelms the loss to vibrationally excited molecular hydrogen at vibrational temperatures as high at 1600 K. At 2500 K the ionization is decreased over the entire planet with little diurnal variation. For Voyager 1 then, unless the H2 vibrational temperature is as high as thousands of degrees and the topside density of H2 is asymmetric and larger by orders of magnitude, dynamical processes are more likely causes of the low electron densities seen in the nightside upper ionosphere. A calculation of the H3(+) density profile showed that the distribution above the turbopause is controlled by diffusion.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 87; Jan. 1
    Format: text
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  • 6
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    Electron precipitation and related aeronomy of the Jovian thermosphere and ionosphere (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A comprehensive theoretical model of both the auroral and nonauroral atmosphere and ionosphere of Jupiter is presented and used to study particle precipitation effects in the Jovian upper atmosphere, both at middle and high latitudes. The sources of energy in the model include extreme ultraviolet radiation and energetic electrons. The precipitation of monoenergetic beams of both one and ten keV electrons at high Jovian latitudes are treated in detail, and the effects of higher energy electrons and soft electrons at middle and low latitudes are considered. The effects of this precipitation, such as airglow excitation, ionization, dissociation, and heating are examined. Calculations of the densities of hydrogen, hydrocarbons, and the important ions as well as the temperatures of the neutral, electron, and ion species are included.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; Aug. 1
    Format: text
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  • 7
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    Studies of Jupiter's lower ionospheric layers (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Fluxes of heavy ions necessary to form layers of enhanced ionization observed in the lower ionosphere of Jupiter are theoretically calculated, and possible formation mechanisms of the layers are investigated. Estimates of ion drift velocities and neutral wind speeds are made from the shape of the ionization layers, and are found to range from a few centimeters per second to meters per second. Zonal wind shear ranges from 50 m/s westward to 200 m/s eastward over a 70 km altitude range, while small meridional winds are sufficient to form the layer. Results indicate that if the layers are formed from sodium or sulfur ions from the Galilean satellite which are injected into the Jovian atmosphere, then the Na(+) flux must be 30,000 sq cm/s, and the S(+) flux must be 4000 sq cm/s in order to correlate with Pioneer 10 observations of the L(6) layer. At low altitudes of the L(6) and L(7) layers, the denser atmosphere makes diffusion very slow, and the vertical drift velocity of 1 cm/s requires a zonal wind of only several centimeters per second to drive it.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 86; Sept. 1
    Format: text
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  • 8
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    Comparison of calculated and measured ion densities on the dayside of Venus (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Data from the Pioneer Venus ion mass spectrometers are compared with model calculations of the ion density distributions appropriate for daytime conditions. The model assumes diffusive equilibrium upper boundary conditions for the major ions (O2(+), O(+), CO2(+), He(+), and H(+)); the agreement between the calculated and measured gross behavior of these ions is reasonably good except for H(+), which may be influenced strongly by convective transport processes. The distributions of five minor ions (C(+), N(+), NO(+), CO(+), and N2(+)) are also calculated for the chemically controlled region (less than approximately 200 km); the agreements are, in general, poor, an indication that the present understanding of the Venus minor ion chemistry is still incomplete.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 205; July 6
    Format: text
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  • 9
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    The energetics of the ionosphere of Venus - A preliminary model based on Pioneer Venus observations (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: A model of the energy balance of the dayside ionosphere of Venus is presented. The coupled energy equations for electrons and ions are solved numerically and the calculated temperatures are compared with temperatures measured by instruments on the Pioneer Venus Orbiter. Neutral and ion density profiles consistent with those measured by various Pioneer Venus experiments are used in the model. It was found that using standard EUV sources and thermal conductivities the calculations produce temperatures that are much lower than the measured ones. Consequently, further calculations were performed in which (1) the thermal conductivities were inhibited by means of an almost horizontal magnetic field and/or (2) heat inflow into both the electron and ion gas at the top of the ionosphere was assumed due to the solar wind interaction. It was found that the calculated and measured temperatures were in reasonably good agreement if the thermal conductivities were inhibited by a near horizontal field of about 10 gammas and if the electron and ion heat fluxes were taken to be 4 x 10 to the 9th eV/sq cm/sec and 10 to the 7th eV/sq cm/sec, respectively.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 6; May 1979
    Format: text
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  • 10
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    The ionosphere and airglow of Venus - Prospects for Pioneer Venus (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The paper presents model calculations for the Cytherean nighttime and daytime ionosphere. It is shown how some of the proposed mechanisms can be tested with the aid of the Pioneer Venus observations scheduled for December 1978. Theoretical calculations of the energetics of the Cytherean ionosphere are performed, and it is concluded that the Project Venus measurements will find elevated ion and electron temperatures, resulting primarily from energy fluxes associated in some manner with the solar wind. According to this model, the energy flux will act directly on the ion gas. Ultraviolet dayglow intensities were calculated, and it is anticipated that hundreds of kR's of CO2-related emission features such as the CO Cameron bands will be observed. Nightside ionosphere calculations were made assuming the precipitation of energetic electrons as an ionization source, and the intensities of some of the resulting emission features are calculated.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 5; July 197
    Format: text
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