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  • 1
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    Testing and Failure Mechanisms of Ice Phase Change Material Heat Exchangers (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Phase change materials (PCM) may be useful for thermal control systems that involve cyclical heat loads or cyclical thermal environments such as Low Earth Orbit (LEO) and Low Lunar Orbit (LLO). Thermal energy can be stored in the PCM during peak heat loads or in adverse thermal environments. The stored thermal energy can then be released later during minimum heat loads or in more favorable thermal environments. One advantage that PCM s have over evaporators in this scenario is that they do not use a consumable. The use of water as a PCM rather than the more traditional paraffin wax has the potential for significant mass reduction since the latent heat of formation of water is approximately 70% greater than that of wax. One of the potential drawbacks of using ice as a PCM is its potential to rupture its container as water expands upon freezing. In order to develop a space qualified ice PCM heat exchanger, failure mechanisms must first be understood. Therefore, a methodical experimental investigation has been undertaken to demonstrate and document specific failure mechanisms due to ice expansion in the PCM. A number of ice PCM heat exchangers were fabricated and tested. Additionally, methods for controlling void location in order to reduce the risk of damage due to ice expansion were investigated. This paper presents the results of testing that occurred from March through September of 2010 and builds on testing that occurred during the previous year.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: JSC-CN-22153 , 41st International Conference on Environmental Systems; Jul 17, 2011 - Jul 21, 2011; Portland, OR; United States
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  • 2
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    Effects of Surfactant Contamination on the Next Generation Gas Trap for the ISS Internal Thermal Control System (2004)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: The current dual-membrane gas trap is designed to remove non-condensed gas bubbles from the Internal Thermal Control System (ITCS) coolant on board the International Space Station (ISS). To date it has successfully served its purpose of preventing gas bubbles from causing depriming, overspeed, and shutdown of the ITCS pump. However, contamination in the ITCS coolant has adversely affected the gas venting rate and lifetime of the gas trap, warranting a development effort for a next-generation gas trap. Previous testing has shown that a hydrophobic-only design is capable of performing even better than the current dual-membrane design for both steady-state gas removal and gas slug removal in clean deionized water. This paper presents results of testing to evaluate the effects of surfactant contamination on the steady-state performance of the hydrophobic-only design.
    Keywords: Spacecraft Design, Testing and Performance
    Type: SAE-04ICES-203 , 2004 International Conference on Environmental Systems 34th Annual Meeting; Jul 19, 2004 - Jul 22, 2004; Colorado Springs, CO; United States
    Format: text
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  • 3
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    Recent Operational Experience with the Internal Thermal Control System Dual-Membrane Gas Trap (2004)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A dual-membrane gas trap is currently used to remove gas bubbles from the Internal Thermal Control System (ITCS) coolant on board the International Space Station. The gas trap consists of concentric tube membrane pairs, comprised of outer hydrophilic tubes and inner hydrophobic fibers. Liquid coolant passes through the outer hydrophilic membrane, which traps the gas bubbles. The inner hydrophobic fiber allows the trapped gas bubbles to pass through and vent to the ambient atmosphere in the cabin. The gas removal performance and operational lifetime of the gas trap have been affected by contamination in the ITCS coolant. However, the gas trap has performed flawlessly with regard to its purpose of preventing gas bubbles from causing depriming, overspeed, and shutdown of the ITCS pump. This paper discusses on-orbit events over the course of the last year related to the performance and functioning of the gas trap.
    Keywords: Spacecraft Design, Testing and Performance
    Type: SAE-04ICES-201 , 2004 International Conference on Environmental Systems 34th Annual Meeting; Jul 19, 2004 - Jul 22, 2004; Colorado Springs, CO; United States
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  • 4
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    Testing and Failure Mechanisms of Ice Phase Change Material Heat Exchangers (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Phase change materials (PCM) may be useful for thermal control systems that involve cyclical heat loads or cyclical thermal environments such as specific spacecraft orientations in Low Earth Orbit (LEO) and low beta angle Low Lunar Orbit (LLO). Thermal energy can be stored in the PCM during peak heat loads or in adverse thermal environments. The stored thermal energy can then be released later during minimum heat loads or in more favorable thermal environments. One advantage that PCM s have over evaporators in this scenario is that they do not use a consumable. The use of water as a PCM rather than the more traditional paraffin wax has the potential for significant mass reduction since the latent heat of formation of water is approximately 70% greater than that of wax. One of the potential drawbacks of using ice as a PCM is its potential to rupture its container as water expands upon freezing. In order to develop a space qualified ice PCM heat exchanger, failure mechanisms must first be understood. Therefore, a methodical experimental investigation has been undertaken to demonstrate and document specific failure mechanisms due to ice expansion in the PCM. A number of ice PCM heat exchangers were fabricated and tested. Additionally, methods for controlling void location in order to reduce the risk of damage due to ice expansion were investigated. This paper presents the results of testing that occurred from March through September of 2010 and builds on testing that occurred during the previous year.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: JSC-CN-23186 , 41st International Conference on Environmental Systems; Jul 17, 2011 - Jul 21, 2011; Portland, OR; United States
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  • 5
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    Model Development and Experimental Validation of the Fusible Heat Sink Design for Exploration Vehicles (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: The Fusible Heat Sink is a novel vehicle heat rejection technology which combines a flow through radiator with a phase change material. The combined technologies create a multi-function device able to shield crew members against Solar Particle Events (SPE), reduce radiator extent by permitting sizing to the average vehicle heat load rather than to the peak vehicle heat load, and to substantially absorb heat load excursions from the average while constantly maintaining thermal control system setpoints. This multi-function technology provides great flexibility for mission planning, making it possible to operate a vehicle in hot or cold environments and under high or low heat load conditions for extended periods of time. This paper describes the model development and experimental validation of the Fusible Heat Sink technology. The model developed was intended to meet the radiation and heat rejection requirements of a nominal MMSEV mission. Development parameters and results, including sizing and model performance will be discussed. From this flight-sized model, a scaled test-article design was modeled, designed, and fabricated for experimental validation of the technology at Johnson Space Center thermal vacuum chamber facilities. Testing showed performance comparable to the model at nominal loads and the capability to maintain heat loads substantially greater than nominal for extended periods of time.
    Keywords: Spacecraft Design, Testing and Performance
    Type: JSC-CN-27335 , 43rd International Conference on Environmental Systems; Jul 14, 2013 - Jul 18, 2013; Vail, CO; United States
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  • 6
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    Design Considerations for Fusible Heat Sink (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Traditionally radiator designs are based off a passive or flow through design depending on vehicle requirements. For cyclical heat loads, a novel idea of combining a full flow through radiator to a phase change material is currently being investigated. The flow through radiator can be designed for an average heat load while the phase change material can be used as a source of supplemental heat rejections when vehicle heat loads go above the average load. Furthermore, by using water as the phase change material, harmful radiation protection can be provided to the crew. This paper discusses numerous trades conducted to understand the most optimal fusible heat sink design for a particular heat load. Trades include configuration concepts, amount of phase change needed for supplemental heat rejection, and the form of interstitial material needed for optimal performance. These trades were used to culminate to a fusible heat sink design. The paper will discuss design parameters taken into account to develop an engineering development unit.
    Keywords: Mechanical Engineering
    Type: JSC-CN-25058 , International Conference on Environmental Systems (ICES); Jul 15, 2012 - Jul 19, 2012; San Diego, CA; United States
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  • 7
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    Experimental Investigation of Ice Phase Change Material Heat Exchangers (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Phase change materials (PCM) may be useful for spacecraft thermal control systems that involve cyclical heat loads or cyclical thermal environments. Thermal energy can be stored in the PCM during peak heat loads or in adverse thermal environments. The stored thermal energy can then be released later during minimum heat loads or in more favorable thermal environments. This can result in a decreased turndown ratio for the radiator and a reduced system mass. The use of water as a PCM rather than the more traditional paraffin wax has the potential for significant mass reduction since the latent heat of formation of water is approximately 70% greater than that of wax. One of the potential drawbacks of using ice as a PCM is its potential to rupture its container as water expands upon freezing. In order to develop a space qualified ice PCM heat exchanger, failure mechanisms must first be understood. Therefore, a methodical experimental investigation has been undertaken to demonstrate and document specific failure mechanisms due to ice expansion in the PCM. A number of ice PCM heat exchangers were fabricated and tested. Additionally, methods for controlling void location in order to reduce the risk of damage due to ice expansion were investigated. This paper presents an overview of the results of this investigation from the past three years.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: JSC-CN-25053 , 42nd International Conference on Environmental Systems; Jul 15, 2012 - Jul 19, 2012; San Diego, CA; United States
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  • 8
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    Experimental Investigation of Transient Sublimator Performance (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Sublimators have been used as heat rejection devices for a variety of space applications including the Apollo Lunar Module and the Extravehicular Mobility Unit (EMU). Sublimators typically operate with steady-state feedwater utilization at or near 100%. However, sublimators are currently being considered to operate in a cyclical topping mode, which represents a new mode of operation for sublimators. Sublimators can be used as a topper during mission phases such as low lunar or low earth orbit. In these mission phases, the sublimator will be repeatedly started and stopped during each orbit to provide supplemental heat rejection for the portion of the orbit where the radiative sink temperature exceeds the system setpoint temperature. This paper will investigate the effects of these transient starts and stops on the feedwater utilization during various feedwater timing scenarios. The X-38 sublimator and Contamination Insensitive Sublimator (CIS) were tested in a ground vacuum chamber to understand this behavior and to quantify the feedwater performance. Data from various scenarios will be analyzed to investigate feedwater utilization under the cyclical conditions. This paper will also provide recommendations for future sublimator designs and/or feedwater control.
    Keywords: Spacecraft Design, Testing and Performance
    Type: JSC-CN-22032 , 41st International Conference on Environmental Systems; Jul 17, 2011 - Jul 21, 2011; Portland, OR; United States
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  • 9
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    Thermal Vacuum Test of Ice as a Phase Change Material Integrated with a Radiator (2009)
    In:  Other Sources
    Details
    Publication Date: 2019-07-19
    Description: Water may be used as radiation shielding for Solar Particle Events (SPE) to protect crewmembers in the Lunar Electric Rover (LER). Because the water is already present for radiation protection, it could also provide a mass efficient solution to the vehicle's thermal control system. This water can be frozen by heat rejection from a radiator and used as a Phase Change Material (PCM) for thermal storage. Use of this water as a PCM can eliminate the need for a pumped fluid loop thermal control system as well as reduce the required size of the radiator. This paper describes the testing and analysis performed for the Rover Engineering Development Unit (REDU), a scaled-down version of a water PCM heat sink for the LER. The REDU was tested in a thermal-vacuum chamber at environmental temperatures similar to those of a horizontal radiator panel on the lunar surface. Testing included complete freeze and melt cycles along with scaled transient heat load profiles simulating a 24-hour day for the rover.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-19194 , 40th International Conference on Environmental Systems; Jul 11, 2010 - Jul 15, 2010; Barcelona; Spain
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  • 10
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    Testing and Model Correlation of Sublimator Driven Coldplate Coupons (2008)
    In:  Other Sources
    Details
    Publication Date: 2019-07-19
    Description: The Sublimator Driven Coldplate (SDC) is a unique piece of thermal control hardware that has several advantages over a traditional thermal control scheme. The principal advantage is the possible elimination of a pumped fluid loop, potentially saving mass, power, and complexity. Because this concept relies on evaporative heat rejection techniques, it is primarily useful for short mission durations. Additionally, the concept requires a conductive path between the heat-generating component and the heat rejection device. Therefore, it is mostly a relevant solution for a vehicle with a relatively low heat rejection requirement. Coupon level tests were performed at NASA's Johnson Space Center to better understand the basic operational principles and to validate the analytical methods being used for the SDC development. This paper outlines the results of the SDC coupon tests, the subsequent thermal model correlation, and a description of the SDC Engineering Development Unit design.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: International Conference on Environmental Systems; Jul 12, 2009 - Jul 16, 2009; Savannah, GA; United States
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