Heat transfer enhancement in pulsating heat pipe by alcohol-water based self-rewetting fluid

Abstract

In the present paper, the heat transfer enhancement parameter is investigated experimentally for a four turns pulsating heat pipe (PHP) designed in a vertical orientation and made of copper (ID 1.30 mm, OD 2.20 mm and total length 1940 mm) for working fluids selected as deionized water (DIW) and 0.1 wt% hexanol in place of self- rewetting fluid (SRWF) at filling ratios (FRs) 10, 50, and 90% and heat input variation 20–140 W. Results indicate the resistance starts decreasing with the further increase in heat input as compared to DIW of SRWF after heat input 80, 100, and 120 W for FRs 10, 50, and 90%, respectively. The higher FR achieves the SRWF behavior at the lower heat input in comparison to the lower FR. Higher FR favors the sinking of heat from hot to cold region in comparison to lower FR for both SRWF and DI. The thermal performance of PHP in the case of SRWFs is explained based on the combined effect of phenomena such as the Marangoni effect, capillary effect, and wettability. The effect of temperature on properties of the working fluid, such as contact angle, electrical resistance, and surface tension of the working fluid is also studied. The occurrence of pulsating action is clarified based on the temperature profile of thermocouples installed in the condensation section at an optimum high 90% FR. © 2020 Elsevier Ltd