The Effect of Nanofluids and Angular Orientation on Pressure and Thermal Characteristics Performance of Oscillating Heat Pipe

Abstract

The article reveals heat transfer performance of multi loops Oscillating Heat Pipe (MLOHP) in terms of thermal resistance and inside pressure characteristics at different angular orientation. Aqueous alumina (Al2O3) and a combination of Al2O3 with multi-walled carbon nanotubes (MWCNTs) particles in a ratio of 90:10 of weight percentages were charged individually into OHP at 60% filling ratio to investigate thermal performance. The influences of aqueous Al2O3 of 0.9 wt% as well as the Al2O3/MWCNTs of same weight concentration on thermal resistance and inside pressure distribution were investigated. The investigation of pressure characteristics inside OHP and optimization of installation angle among 0 degrees, 30 degrees, 60 degrees, 90 degrees with a variation of working fluids were significant in this study. Experimental results showed that thermal characteristics are significantly inter-related with pressure distribution and strongly depend upon the number of pressure fluctuations inside oscillating heat pipe (OHP) per unit time. A little inclusion of MWCNTs into aqueous Al2O3 facilitated the system to achieve highest number of pressure fluctuation and low thermal resistance at OHPs operational angle of 30 degrees and 60 degrees. Thermal resistance decreased with increasing evaporative power input at any orientation for any working fluids employed in this experiment.