The Effect Of Nano-fluid And Surface Treatment On Oscillating Heat Pipe

Oscillating heat pipe/Pulsating heat pipe (OHP/PHP) is a new and special type of heat pipe with simple structure, low cost, excellent thermal performance and good compatibility. In recent, nano-fluid was applied in OHP (Nano-fluid OHP),which combine the high efficient heat conduction of nano-fluid, heat transfer enhancement of the oscillating flow and thin-film eveaporation together. It is considered as one of the most promising resolution to solve heat dissipation problem under small space and high heat flux conduction.Due to Nano-fluid OHP combine gas, fluid and solid together, and consists of complicated flow and heat transfer process,which make its mechanism and heat transfer characteristics more complicated. So, it is necessary to further study the mechanism and the heat transfer rule of Nano-fluid OHP with carefulness. In order to do this, the following experiments were conducted here:(1) The effect of nanofluid on the optimum filling ratio of OHP. (2) The effect of particle shape on heat transfer performance of Nano-fluid OHP. (3) The effect of filling ratio on heat transfer performance of Nano-fluid OHP. (4) The surface treatment effect on heat transfer performance of OHP. The experimental results indicated that:(1)Nano-fluid enhances the heat transfer performance of OHP significantly and decreases optimum filling ratio.(2)The shape of Al2O3 particles can influence the heat transfer performance of OHP significantly, when it is filled with cylinder Al2O3 nano-fluid with volume fraction of 0.5%, the heat transport performance of OHP achieves an optimum value in this experiment. (3) Filling ratio strongly effects the heat transfer performance of OHP and it achieve an optimised heat transfer performance with the filling ration of 30%.(4) It was found that one of the important reasons why nano-fluid can improve the heat transfer performance of OHP is the inner surface modification of OHP by nano-particles. Based on this reason, a new CuO surface is designed, it shows that the surface with CuO microstructure layer can improve the heat transfer performance of OHP significantly.