Effect of carbon nanotube additive on the thermal performance of a horizontal V-grooved heat pipe

An experimental facility to examine the effect of carbon nanotubes (CNT) on the performance of a horizontal V-grooved heat pipe was build. The circular heat pipe was made of copper with an inner diameter of 10 mm and equipped with 10 axial V-grooves with 1 mm depth and 1 mm mouth. The experiment was performed using water as working fluid with mass percentage of CNT of 0%, 1%, 3% and 5%. The optimum fill ratio of the heat pipe was first determined by examining the fill ratio effect on the total resistance. This optimum fill ratio was then used throughout the whole experiment. The evaporator of the heat pipe was heated using a copper heater block equipped with 6 cartridge heaters. The power input to the evaporator was varied from 60 W to 240 W in steps of 60 W with maintaining steady-state operation at each power level. The condenser was cooled by a water jacket fed by a chiller. The surface temperature of the heat pipe was measured by 7 K-type self-adhesive thermocouples connected to data acquisition system. The experimental results showed that the performance of the heat pipe improved with the use of CNT-water mixture in terms of a reduction in the thermal resistance. The results also showed that this enhancement is a function of the amount of CNT additive.