Browsing by Author "Hawkins, Robert"
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Item Advanced Passive Thermal eXperiment (APTx) for Warm Reservior Hybrid Wick Variable Conductance Heat Pipes on the International Space Station(48th International Conference on Environmental Systems, 2018-07-08) Tarau, Calin; Ababneh, Mohammed; Anderson, William; Alvarez-Hernandez, Angel; Ortega, Stephania; Farmer, Jeff; Hawkins, RobertAs NASA prepares to further expand human and robotic presence in space, it is well known that spacecraft architectures will be impacted by unprecedented power requirements and 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 power needs. 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 and tested on the board of the International Space Station (ISS). This testing was performed under the Advanced Passive Thermal eXperiment (APTx) project that is a collaboration between the Johnson Space Center (JSC), Marshall Space Flight Center (MSFC), University of Texas, and Advanced Cooling Technologies, Inc. (ACT) with funding from ISS Technology Demonstration Office at JSC as well as NASA’s Small Business Innovative Research Program. A hybrid-wick copper-Monel-water Variable Conductance Heat Pipe (VCHP) with warm reservoir design that consists of a copper evaporator (with sintered wick), a monel adiabatic section and a condenser both with grooved wick inside was developed and tested successfully on ground. The VCHP worked on the board of the ISS, but at higher temperatures than expected. Hence, a new flight VCHP design is currently under development to mitigate the shortcomings encountered in microgravity. The final paper will include some results and conclusions from the original flight testing and the ground test results for the improved VCHP.Item Demonstration of Copper-Water Heat Pipes Embedded in High Conductivity (HiK™) Plates in the Advanced Passive Thermal eXperiment (APTx) on the International Space Station(48th International Conference on Environmental Systems, 2018-07-08) Ababneh, Mohammed; Tarau, Calin; Anderson, William; Alvarez-Hernandez, Angel; Ortega, Stephania; Farmer, Jeffrey; Hawkins, RobertCopper-water heat pipes are commonly used for thermal management of electronics systems on earth and aircraft, but have not been used in spacecraft thermal control applications to date, due to the satellite industry’s requirement that any device or system be successfully tested in a microgravity environment prior to adoption. Recently, Advanced Cooling Technologies Inc., (ACT), in coordination with engineers from NASA’s Marshall Space Flight Center (MSFC) and Johnson Space Center (JSC) demonstrated successful flight operation of these heat pipes in low-Earth orbit. The testing was conducted aboard the International Space Station (ISS) under the Advanced Passive Thermal eXperiment (APTx) project, a project to test a suite of passive thermal control devices funded by the ISS Technology Demonstration Office at NASA JSC. The heat pipes were embedded in a high conductivity (HiK™) aluminum base plate and subject to a variety of thermal tests over a temperature range of -10 to 38 ºC for a ten-day period. Results showed excellent agreement with both predictions and ground tests. The HiK™ plate underwent 15 freeze-thaw cycles between -30 and 70 ºC during ground testing, and an additional 14 freeze-thaw cycles during the ISS testing. The following was demonstrated during 10 days of testing on the ISS: 1. Successful operation of the copper-water heat pipes and HiK™ plate 2. Ability of the copper-water heat pipes and HiK™ plate to survive multiple freeze/thaw cycles 3. As-designed heat transport via Copper-water heat pipes. 4. Reliable, repeatable start up of Copper-water heat pipes and HiK™ plate from a frozen state. This paper describes the test hardware, ground and flight test campaign, and discusses the results and conclusions of the testing.