Heat transfer enhancement in a three-phase closed thermosyphon

Taking advantage of the heat transfer enhancing effect of a three-phase flow, a three-phase closed thermosyphon (THPCT) was designed and built to improve the heat transfer performance of the conventional two-phase closed thermosyphon (TPCT). Experimental investigations on the effect of various parameters on the thermal performance of the THPCT were carried out. The results were compared with those of the TPCT, focusing on the evaporation heat transfer coefficient and overall thermal resistance. Filling ratio (FR), solid holdup (εs), and input power were considered. The THPCT with 20% carbon fiber-reinforced nylon 66/water showed superior thermal performance compared with the TPCT with pure water. Evaporation heat transfer coefficient was improved by up to 28.5%, and overall thermal resistance was reduced by 11% with FR = 55%, εs = 50%, and an input power of 1000 W. The overall thermal resistance decreased as the solid holdup increased. For tested FR = 45%, 55%, and 65%, an optimal filling ratio (i.e., 55% in this study) is required for the THPCT to obtain the maximum heat transfer enhancing effect.