Capillary pumped-loop thermal performance improvement with electrohydrodynamic technique

The capillary pumped loop (CPL) is a state-of-the-art technology for coolin g spacecraft and telecommunication devices. It is a two-phase heat-transpor t device in which the driving force is provided by the capillary action of the wick material in the evaporator. Compared to the widely used heat pipes , it provides a higher heat-transport capacity, more flexibility of install ation, and greater heat-transport distance because of wickless transport li nes and the absence of liquid and vapor counterflowing, The major disadvant ages of the CPL are long and complicated startup procedures and the possibi lity of deprime at high heat input and large load variations. This paper in vestigates the liquid-vapor separation and thermal management with the elec trohydrodynamic (EHD) technique for an EHD-assisted CPL using R-134a as the working fluid, An experimental investigation, along with a mechanism analy sis, was employed to evaluate the potential of the EHD technique for therma l performance improvement of CPL systems, Experimental results showed that enhancements, up to three times, could be obtained in heal-transfer coeffic ients by applying an electric field at different heat load levels. The depr iming conditions of a capillary pump can also be prevented with the EHD tec hnique.