Numerical Simulation Of The Performance Of A Two-phase Thermal Control System Drived By Pump

Tracker Thermal Control System, a mechanically pumped two-phase carbon dioxide cooling loop of The AMS-2, is an excellent candidate in spacecraft two-phase thermal control system. Comparing to other candidates, mechanically pumped two-phase carbon dioxide cooling loop has obvious superiority. However, the theoretical analysis of its dynamic simulation is rarely reported. The physical model was developed based on the governing equations in two-phase flow and the knowledge of heat transfer and fluid mechanics in this thesis.The main work of the present research includs the calculation of the evaporator and dynamic simulation of the thermal control system. The governing equations for the evaporator are solved with the SIMPLE method. Its flow and heat transfer characteristics are obtained and the effects of working temperture, heating flux and mass flow rate on them are investigated. The Simulink blocks are builded from the equations for the accessories in the system. The temperatures in the inlet and outlet of the accessories and their variations with evaporator heating flux and the surrounding temperature of the condenser are gained with Matlab/Simulink.The results show that the pressure and temperature are decreased along the flow direction in the evaporator but the void fraction is increased, which are mainly affected by heating flux and flow rate. The sharp increase in heating flux will markedly influence the outlet temperature of the evaporator but not obvious to the condenser temperatures. The cyclical variation of the surrounding temperature will result in the marked change of the temperatures of the condenser outlet, the accumulator and the pump but not the evaporator.