EFFECT OF NUMBER OF TURNS ON THE TEMPERATURE PULSATIONS AND CORRESPONDING THERMAL PERFORMANCE OF PULSATING HEAT PIPE

This paper describes the effect of the number of turns on the heat transfer characteristics of closed-loop pulsating heat pipes (CLPHPs). The numbers of turns of the CLPHPs are selected as five, 10, and 20. De-ionized water is employed with a filling ratio of 50%. The effect of the number of turns and operational orientations, such as the vertical bottom and horizontal heating modes with varying heat power, are investigated in relation to the evaporator temperature pulsations and thermal performances of the device. Furthermore, the flow type is explained by the adjacent tube temperature profiles of the adiabatic section. The thermal performance of the device is evaluated by calculating the total thermal resistance, effective thermal conductivity, and average heat transfer coefficient of the device. The experimental results show that by increasing the number of turns of the CLPHPs the device performance is improved and the sensitivity of orientation is reduced. Also, the CLPHPs give better thermal performance under the vertical orientation.