The Theoretical Analysis And Experimental Study Of The Flow And Heat Transfer Characteristics Of The Non-Steady Capillary Pumped Loop (CPL)

Capillary pumped loop (CPL) is an advanced temperature-control device. Heat transfer in CPL is realized with phase transition of working fluid, and the capillary pressure is used for overcoming the resistance in circulatory flow. It is advantageous to apply CPL to temperature-control especially for large spacecraft working in micro-gravity environment.The CPL non-steady characteristics consist of start-up and non-steady operation characteristics. When the temperature the CPL non-steady-operation educing (chiefly the evaporator wall surfaces temperature) deviates from its normal value or displays continual oscillation characteristic after start-up or work-condition-change, the CPL is defined as being in non-steady operation state. The temperature-change of evaporator wall surface is the major operation characteristics. After work-condition-change, the evaporator wall surfaces temperature of the normal operating CPL persistently rises and results in the CPL showing the non-steady characteristics and a failing operation at last. The abnormal flow and heat transfer disciplinarian of the working fluid in CPL induce the CPL non-steady-operation. So it is of great significance to the CPL design that sets up the non-steady flow and heat transfer theory system and finds out the factors to induce non-steady characteristics harmful to system operation, then, further takes effective measures to control and remove its influences.In this paper, the non-steady characteristics educed by the CPL work-condition-change are the chief investigation, which is roundly experimental studied and theoretical analyzed. The theoretical analysis of the CPL system is on the basis of the numerical calculation. Firstly, the accurate simulation of the flow and heat transfer characteristics of the CPL system not only rests with the flow and heat transfer mechanism of the non-steady system, but also depends on the establishment of the corresponding physics model and mathematics model. Then the non-steady operation state of the whole work-condition-changed CPL system is simulated by numerical calculation, which includes in flow and heat transfer characteristics of system components and working fluid. Finally, the flow and heat transfer rules of fluids can be concluded, and the non-steady characteristics of the work-condition-changed CPL system can be analyzed by the distribution figures...