Experimental study on dynamic pressure and temperature regulation of an accumulator in a mechanically pumped two-phase loop

To address the challenge of dynamic regulation of phase-change pressure in a mechanically pumped two-phase loop system in microgravity, this paper proposes a two-phase thermally controlled accumulator with a longitudinal gradient capillary wick. The stability and responsiveness of the system pressure are investigated. A streamlined, integrated two-phase experimental apparatus is established to systematically analyze the dynamic variations in pressure and thermodynamic behavior at different initial subcooling levels and vapor volume change rates. The results indicate that the accumulator's design can autonomously regulate internal fluid distribution and maintain a relatively stable vapor volume, thereby mitigating pressure oscillations induced by the interchange of working fluid mass. Furthermore, the variations in reservoir saturation temperature are confined to 1.1 °C without active regulation. The influence of subcooling on system pressure variations during phase change is also discussed, indicating that an active control strategy involving external cooling and internal heating for thermoelectric coolers should be implemented. This study provides a qualitative foundation for optimizing the accumulator structure and formulating the active control strategy.