Experimental investigations of the thermal performance of self-rewetting fluids in internally finned wickless heat pipes

This paper reports the results of an experimental investigation of heat transfer from a wickless finned heat pipe charged with different self-rewetting fluids. The geometry considered for the experiments comprises an evaporator section of length 200 mm, condenser section of length 200 mm and adiabatic section of length 100 mm. Six constant area fins are placed internally along the length of the condenser. The width of the fin is 5 mm and the thickness is 1 mm. Adding internal fins at the condenser wall gives more surface area to the vapor for heat transfer. This gives additional condensation that keeps the evaporator at safe temperatures and extends the dry out condition. Additionally, fins break the condensed liquid film and augment heat transfer. The fill ratio considered in the present study is 50%. The self rewetting fluids considered in this work are butanol, pentanol, hexanol, and heptanol aqueous solutions. The concentrations of the self rewetting fluids are changed to study the thermal behavior of a heat pipe and the results are compared with those for water charged devices presented in literature. The thermosyphon is tested between power levels of 150 W (heat flux = 9182 W/m2) and 350 W (heat flux = 21424 W/m2). Results confirm superior thermal performance of self rewetting fluids compared to water.