ANALYSIS OF A MULTI-CASCADE METHYL LINOLEATE/SCO_2/TRANSCRITICAL CO_2/R-410A REFRIGERATION CYCLE FOR USE IN HIGH TEMPERATURE HIGH PRESSURE ENVIRONMENTS

摘要

This paper presents the results of an analysis of a hybrid cascaded Methyl Linoleate/Supercritical (SCO_2)/Transcritical CO_2/R-410A cycle for extreme environment refrigeration applications. The particular application of this cascaded CO_2 refrigeration cycle stems from a space exploration application of a Venus lander mission. The payload of the Venus lander is subject an extremely harsh environment, i.e. the objective is to maintain a 1 cubic meter payload cavity at 35°C, with dissipation of 500 W to an environmental temperature of 465°C. Complicating the situation is the Venus local atmosphere is 9 MPa, and the atmosphere is mainly comprised of CO_2 (95.5% by volume, 3.5% N_2 by volume). Because this temperature is so high, to stay under the saturation dome we need some fairly exotic fluids to do a normal vapor compression system. Some of the only fluids with critical points allowing for this particular application are sulfuric acid and Fatty Acid Methyl Ester (FAME) type bio-diesels such as Methyl Linoleate (MLL). The actual heat rejection process and throttling processes are the primary challenges of this research topic. Results of a COP comparison and a lift curve are carried out in order to determine efficiency and guide feasibility of realizing the actual hardware to be used in the cycle.