Thermal performance evaluation of the heat pipe by using 1-pyrene carboxylic-acid functionalized graphene nanofluid

The experiments are conducted to characterize a low-cost nanofluid and evaluate its effect on the sintered-wick heat pipe efficiency. Stable aqueous dispersions of 1-pyrene carboxylic acid (PCA)-functionalized graphene nanofluid were used to investigate the heat transfer characteristics in a sintered wick heat pipe. The various parameters being investigated include different fluids (concentration range from 0.01 to 0.06 mass%), tilt angles of the heat pipe (0 ͦ to 90 ͦ), and input powers (60 W, 80 W, 100 W, and 120 W). The result shows the enhancement of thermal conductivity of nanofluids are in the range of 21% and 40% as concentration and temperature were increased. It is found that the tilt angle of heat pipe has a substantial impact on the thermal properties, which could enhance the thermal performance by 79%. The experimental results indicated that the heat pipe thermal resistance is reduced using these nanofluids. The reduction in thermal resistance was the best at the high heat flux. The most considerable enhancement on overall heat transfer coefficient was achieved at 0.06 mass% by 13.9 kW/K.m2.