Thermal characteristics studies on sintered wick heat pipe using CuO and Al2O3 nanofluids

In the present experimental work, the thermal characteristics of cylindrical sintered wick heat pipe are investigated using CuO and Al2O3 nanofluids. The size and morphology of the nanoparticles are maintained as constant to analyze the distinctive performances of nanoparticles on the thermal enhancement of heat pipe. The effect of inclination angle and heat input on the thermal performance of heat pipe is also studied. The addition of nanoparticles has a notable influence in surface temperature of heat pipe and it is gradually reduced with increasing concentration. The reduction for 0.5 wt.%, 1.0 wt.% and 1.5 wt.% of CuO nanofluids are 2.1 degrees C, 5.9 degrees C and 4.7 degrees C respectively, whereas for the same concentrations Al2O3 nanofluids obtain only 0.9 degrees C, 3.6 degrees C and 5.3 degrees C respectively compared with DI water at horizontal position. Thermal resistance of heat pipe is dramatically reduced with increasing heat flux at low heat input and the reduction is diminished for peak loads. The optimum performance is attained for both CuO and Al2O3 nanofluids at 45 degrees inclination angle. In contrast, the optimum concentration is varied i.e., 1.0 wt.% for CuO and 1.5 wt.% for Al2O3 nanofluids. The evaporation and condensation HTC is increases about 32.99% and 24.59% respectively for CuO and Al2O3 nanofluids at 45 degrees. (C) 2016 Elsevier Inc. All rights reserved.