Heat transfer of closed flat-plat loop pulsating heat pipe in start-up stage

In this paper, the heat transfer process of flat-plate closed loop pulsating heat pipe (FCLPHP) in start-up stage was analyzed. The process of heat transfer of FCLPHP was simplified to two categories: the heat transfer due to the pulsating effect of working fluid and the heat transfer due to the heat conduction through the aluminum flat-plate of FCLPHP. After analyzing the flow pattern of working fluid observed in our visual experiment, we found that the heat transfer due to the pulsating effect of working fluid can be treated as the enhanced heat conduction in start-up stage. By combining two heat conduction processes together with the equivalent thermal diffusivity, we developed a non-steady heat conduction model of FCLPHP. Control volume method was applied to solve the governing equations in the model. The calculated results were compared with the experimental data. The agreement between them shows that the model can accurately describe the heat transfer process of FCLPHP in start-up stage.