2020-07-292020-07-292020-07-31ICES_2020_579https://hdl.handle.net/2346/86409Kuan-Lin Lee, Advanced Cooling Technologies, USACalin Tarau, Advanced Cooling Technologies, USAAndrew Lutz, Advanced Cooling Technologies, USAWilliam Anderson, Advanced Cooling Technologies, USACho-Ning Huang, Case Western Reserve University, USAChirag Kharangate, Case Western Reserve University, USAYasuhiro Kamotani, Case Western Reserve University, USAICES104: Advances in Thermal Control TechnologyThe proceedings for the 2020 International Conference on Environmental Systems were published from July 31, 2020. The technical papers were not presented in person due to the inability to hold the event as scheduled in Lisbon, Portugal because of the COVID-19 global pandemic.The next generation of Lunar rovers and landers require variable thermal links to maintain payload temperatures nearly constant over wide sink temperature fluctuations. It has been demonstrated on earth that a hot reservoir variable conductance heat pipe (VCHP) can provide a much tighter passive thermal control capability compared to a conventional VCHP with cold-biased reservoir. However, previous ISS test results revealed that the fluid management of a hot reservoir VCHP needs to be improved to ensure its long-term reliability. Under an STTR Phase I program, Advanced Cooling Technologies, Inc. in collaboration with Case Western Reserve University performed fundamental research to understand the complex transport phenomena within a hot reservoir VCHP. A novel loop VCHP configuration was developed during the program. This loop design allows a net flow to be induced and circulate along the NCG tubing system, which will continuously remove the excessive working fluid from the reservoir (i.e. purging) in a much faster rate compared to diffusion alone. Two potential mechanisms to induce net transport flow were identified: 1. By momentum transfer from vapor to NCG through shearing in the condenser/front region. It was called “DC” mechanism. 2. By filtering the pulses (via a tesla/check valve) generated in the heat pipe section of VCHP loop. It was called “AC” mechanism. Although these two mechanisms are independent, the AC mechanism can be further added/superimposed on the top of the DC mechanism to achieve a higher flow rate. This paper presents the work performed in Phase I to proof the existence of momentum transfer flow (“DC flow) and its effectiveness on VCHP purging. The work includes theoretical analysis, numerical modeling, prototype development and experimental demonstration.application/pdfengVariable Conductance Heat PipePlanetary Lander Thermal ManagementFluid managementMomentum transfer flowPresentation