Thermal efficiency of heat pipe with alumina nanofluid

The study presents the enhancement of thermal efficiency of heat pipe charged with nanofluid. The Al₂O₃/water nanofluid produced by direct synthesis method is used as the working fluid of experimental heat pipes with three different concentrations (0.5, 1.0 and 3.0 wt.%). The heat pipe is a straight copper tube with inner diameter and length of 8 and 600 mm, respectively. The heat pipes charged with distilled water and nanofluids are tested, respectively. The study discusses about the effects of charge amount of working fluid, tilt angle of heat pipe and weight fraction of nanoparticles on the thermal efficiency of heat pipe. According to the experimental results, the optimum condition of heat pipe is when nanoparticles being at 1.0 wt.%. Under this condition, the thermal efficiency is 16.8%, which is higher than that of heat pipe charged with distilled water. The charge amount can be decreased from 60% to 20%.