Performance characteristics of a vapor compression cooling cycle adopting a closed-loop air-circulation system for avionic reconnaissance equipment

A cooling system is adopted to control the thermal load from avionic equipment in a reconnaissance aircraft such as an unmanned aerial vehicle that undergoes large and rapid environmental changes according to the flight altitude and velocity. In this study, an avionic cooling system using R236fa was manufactured by adopting a vapor compression cycle with a closed-loop air-circulation system. Before the normal tests, the cooling system was optimized by varying the refrigerant charge amount and the expansion valve opening. The performance characteristics of the cooling system were measured by varying the compressor rotating speed, thermal load, evaporator and condenser air flow rates, and condenser inlet air temperature. The performance of the cooling system was analyzed according to these operating parameters, and possible control methods for stable operation of the cooling system were suggested.