Research On Thermal Control Design Of Lunar Micro-ecosphere Based On Thermoelectric Refrigeration Technology

With the development and progress of science and technology,human beings can conduct biological experiments on the moon,but it is quite difficult for living things to survive in the harsh environmental conditions on the moon surface,among which the harsh temperature condition is one of the main limiting factors.The micro-ecosphere on the lunar surface(hereinafter referred to as the "science load")carried on the chang’e-4lander is the first biological growth and cultivation experiment on the lunar surface,and the internal temperature control is realized through the thermoelectric refrigeration technology.In this paper,the thermal control module of the science load is designed,and through simulation and heat balance test to analyze whether the internal temperature of the load can be maintained within the range suitable for living organisms under the extreme temperature of the lunar surface.In addition,the characteristics of the TEC operating in vacuum were analyzed.The research conclusions provide reference for the future application of thermoelectric refrigeration technology in aerospace.The main research work and the results are as follows:(1)Heat transfer analysis and calculations were performed on the thermal control module of the load.According to the calculation results,the TECs,the radiator and the heat pipe were designed.The optimal working voltage of the TECs were initially determined by simulation.The simulation results show that,except for the extreme conditions of the lunar daytime,other working conditions can ensure that the temperature of the installation position of the biological cabin is between 0 °C and35 °C。(2)The rationality of the thermal control design of the lunar micro-ecosphere system was verified by thermal equilibrium test.The experimental results show that the internal temperature of the load during the nominal working conditions and the lunar night can be maintained between 0 °C and 35 °C.In addition,after the TECs stop working,when the inside of the load completely reaches the steady state,the temperatures of lunar daytime and night were 51.94 ° C and-55.15 ° C,respectively.(3)The limit equilibrium temperature prediction model of the heat balance test was verified,and the science load was determined to meet the model in the heat balance test.According to the model,the limit equilibrium temperature of the installation position of the biological cabin under each working condition was obtained by using the test data.By comparing the experimental temperature with the simulation results,it is found that the maximum error of the two is below 4 °C,and the cause of the error is analyzed.(4)By using the prediction model of the limit equilibrium temperature in the heat balance test,the temperature of the hot and cold side of the TEC is obtained when the respective conditions reach the steady state.According to these data,the working parameters of the TEC under various working conditions are obtained.It is proved from these parameters that the optimal working voltage of the TEC used is 2.0V.When the temperature difference between the hot and cold sides exceeds 55.7 ° C,the heat transferred from the hot side to the cold side will be greater than the amount of cooling it produces.In addition,it is also proved that when the working condition of the TEC is constant,the increased cold side load can increase the COP of the TEC.When the ambient temperature changes,the resistance of the TEC also changes,and when the ambient temperature drops,the resistance of the TEC also decreases.