Abstract
Heat pipe has been widely used for the thermal management of electronic products. The concept lies in the fact that the latent heat derived from phase change can absorb the heat generation of the chips. As a result, the massive quantity of heat can be quickly transported from the evaporation region to the condensation region. Advantages of flat heat pipe for the heat transfer of electrical devices are as follows. (1) Most of heat pipes are of cylindrical shape, which inherently has a contact problem with flat electronic chips. However, there is no such a drawback for flat heat pipes. (2) The volume of working fluid inside the flat heat pipe and the thermal contact resistance across the interface between chips and heat pipes can increases and decreases, respectively. Thus, both of the total weight and price are greatly reduced. It should be noted that the flat heat pipe adopted here is not the product found in the common market which is composed of several cylindrical heat pipes arranged in parallel with one another. This experiment is placed horizontally to simulate the most situations of electronic products. The chip is altered by a KAPTON electroncaloric sheet served as a heat source, and the water jacket as a heat sink in our experiment. The water cooling is used in the condensation region to achieve a greater temperature difference between the ends of flat heat pipes and thereby to facilitate the experimental observation. There are two primary objectives in this work. (1) The first one is to investigate the influence of capillary force, properties of working fluid and wick structures on the cooling limit of chips. (2) The second one is to observe the whole phenomena of working fluid inside flat heat pipes from a startup to a steady state. We hope to find out a suitable combination of flat heat pipe whose cooling capacity is better through the visualization of experiment.