Investigation on transient behaviors of flat plate heat pipes

By means of both experimental and theoretical approaches, this paper is aimed to study performance and mechanism of a flat plate heat pipe (FPHP) in which a layer of sintered copper powder is applied to the heated surface of the heat pipe to enhance evaporation process. The performance of the FPHP is experimentally measured under different heat fluxes, orientations and amount of the working fluid in order to investigate the effects of charge amount of the working fluid, thickness of the sintered layer, and orientation of the heat pipe on the performance of the FPHP. On basis of some assumptions, a theoretical model is proposed to simulate dynamic behavior and steady-state performance of the FPHP. The model and simulation method developed in this article are verified by the experimental results. Simulation shows that dynamic behavior of a FPHP is affected by geometrical parameters, charge amount of the working fluid and installation orientation. The porous sintered layer on the heated surface can enhance evaporation process and improve performance of the FPHP. Such a technique ensures proper operation of the heat pipe at high heat flux in arbitrary orientation. With regard to the potential application to electronic cooling, comparison between the FPHP and conventional solid heat sink is provided. Compared with the solid heat sink, the FPHP has great potential for electronic elements with high power consumption because of its unique performance of high response, efficiency, isothermal and lightweight feature.