Startup characteristics of pump-assisted capillary phase change loop

In this study, startup characteristics of a pump-assisted capillary phase change loop under various operational conditions were experimentally investigated. For the loop fabrication, a self-designed impeller pump was selected to reduce the volume and weight of the loop. Methanol was chosen as the working fluid. The test results indicated that the pre-conditions in the evaporator had a large impact on the startup characteristics. When the vapor chamber was occupied, partially or completely, with liquid before startup, a temperature overshoot appeared in the heater wall temperature profile. As a higher heat load was applied to the evaporator, vapor bubbles generated in the compensation chamber. Under these conditions, the loop still operated steadily, and the heat transfer capability of the evaporator improved. To avoid the boiling conditions that appeared in the compensation chamber, either lowering the heat sink temperature or increasing the pumping power was the effective manner.