Study on Gravity Independence of Compressor Performance for Space-borne Vapor Compression Heat Pump
gravity independence, compressor, space-borne, heat pump, performance
Aerospace technology plays an important role in the modern scientific research and engineering applications. Most energy consumed by equipment inside the spacecraft is converted into waste heat. Current thermal control and management technology research for international aerospace has made considerable progress. Vapor compression heat pump is an important aerospace thermal control means to lunar probe program and deep space exploration. Compressors are the most important components in vapor compression heat pump systems. How to improve the performance of aerospace refrigeration compressors is a key technology. Micro-gravity environment has a great impact on system performance. For the study of the performance of compressor and heat pump system under micro-gravity environment, a test bed for the gravity independence of space-borne vapor compression heat pump system is designed and built. The test system of gravity independence mainly consists of three parts: refrigerant cycle system, water cycle system and data acquisition system. The paper tests the gravity independence of rotary compressor performance, and evaluates the performance of compressor and heat pump system in micro-gravity environment. The results show that when the control voltage of compressor speed is 2 V, the maximum tilt angle is about 60° under the condition of low speed operation. The inclination angle of compressor has little effect on evaporation and condensation pressure. Evaporation and condensation pressure is 4.3 bar and 12 bar, respectively, and the pressure ratio is steady. Energy efficiency ratio and coefficient of performance are about 3.3 and 4.2, respectively. Under the condition of the maximum tilt angle of 60°, the system could run in the compressor speed control range of 1-3.5 V. There’s a balance point when the control voltage is 1-2 V, and the maximum of energy efficiency ratio and coefficient of performance are 3.1 and 4.0, respectively. When the voltage is 2.5-3.5 V, the compressor suction and exhaust temperature is difficult to stabilize, showing a periodical rise and fall. If the voltage is more than 3.5 V, the compressor stops to run for self-protection. Under the condition that the compressor works in full, the maximum tilt angle is 20°. When the tilt angle is less than 20°, the compressor is under normal operation; when the tilt angle is more than 20°, the compressor can not continue to maintain the operation, resulting in downtime. When the tilt angel is less than 20°, the performance parameters do not change with the increase of the inclination angle. Evaporation and condensation pressure stabilize at 4.2 and 13 bar, respectively. Energy efficiency ratio and coefficient of performance are about 2.7 and 3.6, respectively. Under the condition of the tilt angle of 15°, as the control voltage increases from 1.5 to 5 V, the energy efficiency ratio decreases from 3.5 to 2.7, and the coefficient of performance drops from 4.2 to 3.6.
Study on gravity independence of compressor performance for space-borne vapor compression heat pump