Speaker
Description
Advanced Cooling Technologies (ACT) conducted structural and thermal assessment of titanium-water (Ti-H2O) heat pipe and Graphite Fiber Reinforced Composite (GFRC) face sheet-based radiators for Fission Surface Power (FSP) applications. ACT previously developed and fabricated these radiator panels by directly bonding GFRC face sheets to titanium-water heat pipes. The heat pipes incorporated a proprietary wick structure within the evaporator. In addition, non-condensable gas (NCG) was used to provide startup assistance and freeze-thaw tolerance. The GFRC face sheets featured an unique alignment of carbon fibers to cancel the Coefficient of Thermal Expansion (CTE) mismatch with titanium in the axial direction. Recently, ACT performed numerical analysis of structural integrity of the radiators under launch vehicle shock and vibration environments. The analysis identified optimized structural reinforcements configurations that exhibited successful structural response to random vibration loads corresponding to launch conditions. Following the fabrication and assembly of structural reinforcements, radiators will undergo experimental shock and vibration testing. Thermal testing will be conducted before and after the shock and vibration testing and will be used to evaluate the response of radiators to launch vehicle loads. In addition, face sheet material and its bonding with titanium heat pipe will be characterized for any structural damage. Success of shock and vibration testing will be evaluated from the structural integrity of the radiators, and their power rejection capability. In addition, ACT conducted detailed freeze-thaw tolerance performance testing of the heat pipe using two different freezing methodologies. First, in the case of freezing only the condenser; whereas the evaporator remained warm, the heat pipe showed 12 successful freeze-thaw tolerant cycles of testing without failure. In the second case of freezing the entire heat pipe, a total of 10 successful freeze-thaw tolerance tests were conducted without any failure. Following each freeze-thaw cycle, the heat pipe regained its performance, and the radiator module rejected same amount of power at similar operating conditions. Finally, ACT performed a theoretical assessment of the probability of heat pipe failure and face sheet area loss resulting from micrometeoroid impacts over a 10-year operational lifetime in the lunar environment.