Experimental study on the transient behaviors of mechanically pumped two-phase loop with a novel accumulator for thermal control of space camera payload

Abstract

Mechanically pumped two-phase loop (MPTL) shows a promising prospect in thermal control of space camera payload. However, transient behaviors of MPTL caused by start-up and heat sources load-on/off are rarely reported. In the present study, one MPTL setup was designed and constructed to reveal them. Particularly, a novel two-phase thermal-controlled accumulator integrating with passive cooling was designed and employed to replace the traditional accumulator. The obtained test data, including the temperatures, pressures and mass flow-rate, were invited to analyze the dynamic behaviors of MPTL during the whole processes, the dynamic behaviors of accumulator, and the coupled heat and mass transfer processes between main loop and the accumulator. Vapor lock took place during the phase changing process and leaded to oscillations of flow resistance and mass flow-rate. During processes of heat sources load-on and load-off, two oscillations of temperature and pressure in the accumulator were both needed for the MPTL returning to stable. Meanwhile, fluctuation patterns at these two processes were opposite. Lowering the pump speed decreased the stable temperatures of evaporator, flow resistance as well as the mass flow rate. An average temperature decrease of 0.43 °C was presented after changing the pump speed from 26,700 r/min to 20,000 r/min.