Simulation And Optimization Research For Spacecraft Heat Pump

With the continuous development and progress of space technology in our country,the scale and function of manned spacecraft becomes larger than before,so the waste heat caused by instruments and equipment in the spacecraft increased day by day.When the waste heat got to a certain amount,astronauts' normal life would be under the influence of waste heat.Therefore,how to expel waste heat from the spacecraft becomes an important research.Aiming at the problem for expelling of waste heat in the spacecraft,many plans were put forward by specialists from domestic and overseas including single-phase fluid loop,two phase fluid loop,capillary pump loop,heat pump loop,etc.At present,the former three plans have already applied to actual manned spacecraft,but application of heat pump loop for expelling of waste heat in the spacecraft remained to be perfected further.For spacecraft heat pump,the main problems are optimization of heat pump flow,selection of refrigerant,optimization of heat rejection temperature,analysis of thermal control system weight.In view of this,theoretical research for the weight of spacecraft heat pump was made by this paper.The weight models of single stage compression and two-stage compression heat pump were built,and heat rejection temperature was optimized for the purpose of the lightest weight.Comparing the weight of single stage compression heat pump with the weight of two-stage compression heat pump,the heat pump flow was chosen by the aim of good property and light weight.Aspen plus was used to choose the best heat pump working fluid,the exhaust gas temperature,power consumption,refrigerating capacity and refrigeration coefficient of single stage compression with or without regenerative cycle were calculated based on NRTL-RK property method,the parameters of heat pump flow with regenerative cycle were optimized aiming at increasing refrigeration coefficient.According to the simulated flow,a heat pump performance test device was set up.The influence of regenerative cycle on the performance of spacecraft heat pump was studied.Comparing simulated result with experimental result,the reliability of actual heat pump process simulated by Aspen plus was verified.Making research by theory,the results show that when the evaporating temperature gets to 300 K,the best heat rejection temperatures of single stage and twostage compression heat pump are 370 K,and at this time,the lightest weight of singlestage compression heat pump is smaller than the lightest weight of two-stage compression heat pump.Therefore,considering the light weight of heat pump,the best choice is to use single-stage vapor-compression as spacecraft heat pump.The simulation results by Aspen plus show that,the best refrigerant for singlestage vapor-compression heat pump in spacecraft is R12.At the same internal temperature of spacecraft,heat pump with regenerative cycle can enhance refrigeration coefficient effectively.The inlet temperature of compressor and the outlet temperature of cold liquid in the heat regenerator under regenerative cycle were optimized.After being optimized,refrigerating capacity gets to maximum 98.11 W,and the optimized result is 4.6% more than the previous simulation result.power consumption of compressor gets to the minimum 126.5W decreasing by 2.1% than the previous simulation result.The refrigeration coefficient gets to 0.78,increasing by 6.8% more than the previous simulation result.The experimental results by heat pump performance test show that,even though regenerative cycle can improve refrigerating capacity effectively,it also causes the increase of power consumption of the compressor and the rising of exhaust gas temperature.However the increasing range of refrigerating capacity is bigger than power consumption,when the calorimeter temperature gets to 16?,20?,24?,28?,the growth rates of refrigeration coefficients caused by regenerative cycle are 50%,39.6%,32.7%,27.6% respectively,so it was effective for R12 regenerative cycle to improve refrigeration coefficient.Through comparing experimental COP with simulated COP,the variation trends for them are almost the same,and the maximum relative error is small.When the internal temperature of spacecraft is 24?,the fitting degree between experimental COP and simulated COP is the highest.At this time,the relative error is 1.45% with regenerative cycle,and 1.92%without regenerative cycle.It indicates that the software simulation of the actual heat pump flow is feasible.