Browsing by Author "Ababneh, Mohammed T."
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Item Advanced Passive Thermal Experiment for Hybrid Variable Conductance Heat Pipes and HiK™ Plates on the International Space Station(47th International Conference on Environmental Systems, 2017-07-16) Ababneh, Mohammed T.; Tarau, Calin; Anderson, William G.; Farmer, Jeffery T.; Alvarez-Hernandez, Angel R.; Ortega, StephaniaAs NASA prepares to further expand human and robotic presence in space, it is well known that spacecraft architectures will be challenged with unprecedented thermal environments in deep space. In addition, there is a need to extend the duration of the missions in both cold and hot environments, including cis-lunar and planetary surface excursions. The heat rejection turn–down ratio of the increased thermal loads in the above-mentioned conditions is crucial for minimizing vehicle resources (e.g. power). Therefore, future exploration activities will have the need of thermal management systems that can provide higher reliability and performance, and power and mass reduction. In an effort to start addressing the current technical gaps in thermal management systems, novel new passive thermal technologies have been selected to be included as part of suite of experiments to be tested on the board of the International Space Station (ISS), tentatively in 2017. Advanced Cooling Technologies, Inc. (ACT), together with NASA Marshall Space Flight Center and NASA Johnson Space Center, are working to test and validate hybrid wick VCHP with warm reservoir and HiK™ plates on the ISS under the Advanced Passive Thermal experiment (APTx) project. The APTx consists of two separate payloads that will be tested sequentially: • Payload 1 contains a VCHP/HiK™ plate assembly: a hybrid-wick copper-Monel-water VCHP design consists of a copper evaporator (with sintered wick inside), a monel adiabatic section and a condenser both with grooved wick inside and a NCG reservoir thermally and physically attached to the evaporator. In turn, the VCHP evaporator is mounted on an aluminum HiK™ plate. • Payload 2 contains a HiK™ plate and the ElectroWetting Heat Pipe (EWHP) experiment, developed by the University of Texas at Austin. This paper will cover the results to date for the flight test, which is planned for 2017.Item Hybrid Heat Pipes for Planetary Surface and High Heat Flux Applications(45th International Conference on Environmental Systems, 2015-07-12) Ababneh, Mohammed T.; Tarau, Calin; Anderson, William G.Novel hybrid wick Constant Conductance Heat Pipes (CCHPs) were developed to solve the high heat flux limitation for future highly integrated electronics. In addition to carrying power over long distances in space, the hybrid CCHP evaporator can also operate against an adverse tilt on the planetary surface for Lunar and Martian landers and rovers. These hybrid heat pipes will be capable of operating at the higher heat flux requirements expected in NASA’s future spacecraft and instruments such as on the next generation of polar rovers and equatorial landers. The thermal transport requirements for future spacecraft missions continue to increase, while at the same time the heat acquisition areas have trended downward, thereby increasing the incident heat flux from 5-10W/cm2 to the projected > 50W/cm2. This exceeds the performance of standard axial groove CCHPs and loop heat pipes (LHPs). Aluminum/ammonia and stainless steel/ammonia hybrid CCHPs to demonstrate high heat flux capability and for planetary (Lunar and Martian) rovers and landers were designed, fabricated and tested. The CCHPs had a sintered powder metal wick in the evaporator and axial grooves in the adiabatic and condenser regions The hybrid wick high heat flux aluminum/ammonia CCHP transported a heat load of 175 watts with heat flux input of 53W/cm2 at 0.1 inch adverse elevation. This demonstrates an improvement in heat flux capability of 3 times over the standard axial groove CCHP design. The hybrid wick high heat flux stainless steel/ammonia CCHP transported a heat load of 165 watts with heat flux input of 51W/cm2 at 0.1 inch adverse elevation. The Thermal Link planetary aluminum/ammonia CCHP transported approximately 202 watts at a 4.2° adverse inclination before dryout, exceeding the 150W target. Also the Thermal Link planetary aluminum/ammonia CCHP was tested for maximum transport power at three different adverse elevations to extrapolate zero-g power. The maximum power at zero-g is 288 watts, exceeding the 150W target. The X-ray micrographs for the interface between the sintered powder metal wick and the axial grooves in the stainless steel hybrid CCHP shows much better contact in comparison to the aluminum CCHP because of the successful internal sintering technique developed during this project.