Through the experimental study on the characteristics of wall temperature oscillation of copper-water single-loop pulsating heat pipe, this paper reveals the influence of heat transfer rate, charging ratio and pipe diameter on start-up and heat transfer performance of heat pipe. The experiment used air-cooled under constant heat flux input for testing the wall temperature characteristics curve of heating section and cooling section of heat pipe in the stable operation condition. The internal relation between temperature oscillation and heat transfer rate of heat pipe was obtained, and the influences of charging ratio and pipe diameter on wall temperature characteristics curve of heat pipe were studied. The results indicated that wall temperature oscillation of heat pipe presented four states under the situation of increasing heating power： non-oscillatory, oscillation starting, sharply oscillation and small uniform oscillation. The oscillation frequency changed from low to high and placed in high stable oscillation. Charging ratio and pipe diameter affected start-up power, amplitude and frequency of heat pipe. The start-up power of heat pipe which had intermediate value in charging ratio and pipe diameter was minimum. The smaller pipe inner diameter was, the larger charging ratio and temperature amplitude of heat pipe were. The average oscillation frequency of heat pipes which had intermediate value in charging ratio and pipe diameter was maximum, while heat pipes which had larger pipe diameter and smaller charging ratio had the minimum average oscillation frequency. The temperature oscillation changed into small uniform oscillation when the heat transfer rate reached a certain value, and the influence of charging ratio and pipe diameter on amplitude and frequency became smaller.
Proceedings of the CSEE
single-loop pulsating heat pipe
pipe wall temperature