Investigation On The Mechanism Of The Phase Change Heat Transfer In The Oscillating Heat Pipe

In the paper, we use the high speed CCD to investigate the oscillating heat pipe with 3mm inner diameter in the visualization experiment. We can find there is a startup power in the startup period during the operation process of heat pipe. Only when the input heat power is higher than the startup power, the heat pipe can operate steady. The fluid in the heat pipe is under the state alternately changed of quasi-equilibrium and oscillating with different input heat power. With the increase of input heat power, the time rate of quasi-equilibrium in the heat pipe is getting lower. With the increase of input heat power, the flow patterns change from slug-plug flow, half circuit flow and circuit flow correspondingly. In the same time we can find the nucleate boiling bubbly flow etc. It is observed the performance with the angle of 45°is the best. In this paper, we discuss the physical and mathematical model of loop oscillating heat pipe. The result of numerical simulation shows that the vapor bubble's expanding and compressing alternately keeps the fluid oscillating in the heat pipe. The oscillating flow is influenced by the angle, filling rate and input heat, and its trends are basically consistent with the previous experimental results.