Feasibility investigation on potential working fluids for electrohydrodynamically-assisted CPLs

Abstract

The capillary pumped loop (CPL) is a state-of-the-art device for efficient cooling of electronic components used in spacecraft and telecommunications. CPL functions on a two-phase heat transport process in which a working fluid is driven by the pumping effect of the capillary action of a wick material imbedded in the evaporator. The wick structure is imbedded only in the CPL evaporator, and the rest of the loop is a simple wickless smooth tube. Therefore, compared to the widely used heat pipe, CPL provides a substantially higher heat transport capacity, more flexibility of installation, and a much greater distance of heat transport. The major disadvantages of the CPL, however, are the long and complicated start-up procedure, and the possibility of depriming at the high heat input and load variation. The main focus of this paper is on selection of potential working fluid candidates for use in Electrohydrodynamic (EHD)-enhanced CPLs. In this connection, a series of feasibility studies on various CPL working fluids have been performed and will be discussed. Among the working fluid candidates, propane and propylene are found to be the promising candidates. For appropriate electrode configuration, experimental results showed that the EHD pumping head of propane and propylene was high. Therefore, the two natural refrigerants, propane and propylene, are expected to improve the performance of EHD-enhanced CPLs.