Venus Lander Electronics Payload Thermal Management Using a Multistage Refrigeration System

Abstract

This paper presents the analysis and optimization of multistage refrigeration thermal control system for use in cooling electronics payloads on Venus lander missions. The paper outlines the challenges associated with thermal management of electronics in the extreme temperature and pressure environment of Venus. The multistage cascaded vapor compression refrigeration is comprised of a topping cycle using methyl linoleate fatty acid methyl ester with intermediate Supercritical Carbon Dioxide and Transcritical Carbon Dioxide cycles and a bottoming cycle using R-410A refrigerant. Results for analysis optimization of the cascade cycle using MATLAB’s genetic algorithm are presented, which demonstrate the effect of the low-side evaporator pressure on the coefficient of performance of the system. A study of the bottoming working fluid selection shows Ammonia to be a better candidate working fluid for the bottoming cycle than R-410A refrigerant. The paper then presents analysis results for the four-stage cascade refrigeration cycle Ammonia/Supercritical Carbon Dioxide/Transcritical Carbon Dioxide/Methyl Linoleate Fatty Acid Methyl Ester for a refrigeration effect of 100 W with payload at 100°C and a hot-sink temperature of 465°C, lending an optimized total cycle compressor power of approximately 115 W corresponding to a coefficient of performance of 0.87 for the cascade system. The paper presents preliminary design of the heat-rejection system radiator used to interface the cascaded system to the Venus atmosphere.