EXPERIMENTAL STUDY OF THE THERMAL PERFORMANCE OF A WATER-COPPER VARIABLE CONDUCTANCE HEAT PIPE WITH SCREEN MESH WICK

摘要

This study has been performed to experimentally investigate the influence of NCG charging mass on the heat transfer of variable conductance heat pipe (VCHP) with non-condensable gas which is used to maintain the small variation of surface temperature in an evaporator with the fluctuation of heat flow rate. Constant conductance heat pipe (CCHP) has its high working reliability, but it has the weak point in the maintaining and controlling of temperature under the extreme change of thermal environment. To avoid this malfunction as mentioned above, the VCHP is recommended. The methods of controlling of thermal resistance in VCHP are controlling of liquid flow rate, controlling of vapor flow rate and controlling of condensing section area. In this study, we adopted the last method as is controlling the active condenser length by charging of non- condensable gas in the condenser section. The heat pipe was designed in 200 screen meshes, 500 mm length and 12 mm O.D tube of copper, water as working fluid charged in a mass of 4.8 g, and nitrogen as a non-condensable gas. Experimental data for the wall temperature distribution along axial length will be presented with respect to changing of heat load imposed on the evaporator of heat pipe, the temperature of condenser cooling water, the degrees of inclination angle and operating temperature of heat pipe. Experimental tests verify that the initial operating temperature and the overall wall temperature of heat pipe increase with NCG charging mass increasing.