AN EXPERIMENTAL STUDY OF HEAT TRANSFER CHARACTERISTICS OF THE EVAPORATOR IN A SEPARATE-TYPE HEAT PIPE

摘要

An experimental investigation was conducted to detect the heat transfer characteristics of the evaporator in a separate-type heat pipe, which was set horizontally or with small inclination angle. The wall temperature distribution and heat transfer characteristics were obtained. Studied were the effects of heat fluxes, working temperatures, inclination angles, and quantities of actuating to heat transfer. In comparison with the vertical evaporator, a heat transfer deterioration was obtained in horizontal and inclined ( θ <5 °) evaporators. The results show that the temperature difference between the top and bottom wall increases when heat flux exceeds 20 kJ/m~2. There exists a large fluctuation for the top wall temperature along the axes of the evaporator tubes, which results in a reduction of the average heat transfer coefficient. Lower dry-out heat flux was examined in such evaporators. In addition, an empirical dimentionless correlation was developed for the average heat transfer coefficient of horizontal evaporators.