Experimental study of two-phase closed thermosyphon with super-hydrophilic and super-hydrophobic surfaces

In this study, the heat transfer performance of a two-phase closed thermosyphon with super-hydrophobic (SH-phobic) condenser and super-hydrophilic (SH-philic) evaporator is investigated, and the results are compared with those of a bare condenser. At 100–200 W, the total thermal resistance on the SH-phobic surface decreases by up to 10.40 %, 0.41 % and 27.44 % compared with the bare condenser surface at filling ratios of 0.25, 0.5, and 0.75, respectively. However, the total thermal resistance increases by 55.06 %, 411.35 % and 128.33 % from 300 to 400 W, respectively. The critical heat flux for the SH-phobic surface is lower than for the bare surface. The SH-phobic surface performs better than bare surface in the low-power region (100–200 W), but not in the high-power region above 300 W. Therefore, the input power should be considered when applying the SH-phobic surface to the condensing section.