Thermal vacuum testing for constant temperature control of loop heat pipe using Electrohydrodynamic conduction pump

Loop Heat Pipes (LHPs) are two-phase heat transfer devices that are widely utilized in spacecraft configurations. In this study, we developed a novel temperature control technique using electrohydrodynamic (EHD) conduction pumps for the heat switch function. An EHD conduction pump was integrated in the liquid line of an LHP, generating an opposing pressure to the capillary force, thereby regulating the working fluid flow and controlling heat transfer. This paper presents the design and fabrication of the experimental EHD pump and the experimental results of evaporator temperature control testing in a thermal vacuum environment. The evaporator temperature was successfully maintained at a constant setpoint over 24 h in a low-temperature environment using a dedicated control system. The control effect was verified under two sink temperature conditions, demonstrating that the EHD pump can adequately control the LHP temperature. The power consumption of the EHD pump under control was 27 mW. The detailed analysis confirmed two different LHP operation modes controlled by the EHD pump: flow regulation mode and flow switching mode. The operating mode switched depending on the required thermal resistance.