Heat Transfer Characteristics of Oscillating Heat Pipes

Abstract

Abstract

This article investigates the heat flux characteristics of oscillating heat pipes (OHPs). The oscillatingheat pipes have 3 types as follows: closed end oscillating heat pipe (CEOHP), closed looped oscillating heatpipe (CLOHP) and closed looped oscillating heat pipe with check valves (CLOHP/CV). The analysis wasperformed on the existing experimental data in the literature. The heat transfer characteristics of all typesof oscillating heat pipes were compared and analyzed. The OHPs were compared in terms of the heat flux(W/m2) at normal operation; the effects of the angle of inclination and the use of different working fluidswere evaluated. Based on the analysis results, it was found that the inner diameter (Di) should be closed tothe theoretically recommended value if the highest heat transfer effectiveness is to obtain. The decreasedsection lengths (Le, La and Lc) of OHPs increase the heat flux because the distance for heat transfer is shorter;heat loss would also be less. The horizontal operation mode of CLOHP/CV exhibits maximum heat flux.The working fluids effect on the heat flux is significant, which is in accordance to the heat transfer theory.

Keywords : Heat flux; Oscillating heat pipe; Thermal performance