Research And Development Of Heat Pump Heat Rejection System

Heat pump system is widely considered as the next generation thermal control technology of spacecraft because of being able to take advantage of the refrigerant latent heat, raising radiator temperature, improving the quality of waste heat and having a higher COP. As the key technology of heat pump system, compressor is directly related to the performance of it. In this paper, a micro-heat pump performance test system was set up, experimental studies were carried out, a space radiation condenser was designed, a miniature heat pump system prototype was designed and developed, and oprating characteristics were conducted.Firstly,an experimental system is designed and set up for investigating the operation characteristics of miniature heat pump system, refrigerating output, power input and COP were obtained under different work conditions. The measured results indicate that the optimal charging quantity is 220g, the maximum refrigerant output is 279W and COP is 2.31 in conditions of 18℃chilled water and 35℃cooling water. When the cooling water temperature raised from 21℃to 47℃, the cooling capacity decreased from 505W to 426W and the COP reduced from 5.64 to 2.78. When the chilled water temperature raised from 18℃to 52℃, the cooling capacity increased from 236W to 637W and the COP increased from 2.01 to 5.40. Cooling capacity and power consumption increase rapidly as the control voltage changed from 1V to 5V, but COP decrease. Moreover, a 48 hours'stability test was conducted, the compressor can run well with a 400W refrigerant capacity.A 450W heat rejection fin-tube radiator was designed; a thermal analysis model was established; curves were obtained which described variations of heat rejection capacity of radiators per unit area, radiator weight and fin efficiency against fin width and tube diameter. Optimal fin width was determined based on the maximum heat rejection capacity of radiators per unit area, after that the other parameters were all calculated, the curves against temperature along fin width were obtained. Composite heat rejections include nature convection and thermal radiation in different environment temperature on the ground which the fin-tube radiator rejected was analysis and the heat rejection curves were got.A miniature heat pump system prototype was designed and developed, and operating characteristics were conducted. In conditions of 22℃environment temperature and 19℃chilled water inlet temperature, the best refrigerating charge was 180g with a maximum refrigerating output which was 344W. When the chilled water inlet temperature was 29℃, the refrigerating output could reach more than 500W of the prototype which operated smoothly with low noise persistently. Finally the problems of the miniature heat pump prototype were analyzed and improvement scheme were put forward.