Experimental Study of Ageing Effect in Pool Boiling Heat Transfer

摘要

In recent years, there is an increasing need for better cooling solutions to maintain a uniform and low temperature in high power density electronic devices. With much research effort devoted to it, pool boiling has been identified as a promising method to remove heat with less moving parts and high efficiency. The phase change during pool boiling can absorb large amount of heat and the nucleating bubbles can evacuate into the liquid pool automatically due to buoyance force, thereby assuring liquid rewetting of the heat sink surface and lower its working temperature. For the utilization of pool boiling heat sinks in industries like power generation plants, data centers and military systems, heat sinks are expected to operate consistently with high performance. Therefore, the effect of aging on heat sink performance needs to be evaluated closely. In this study, pool boiling experiments have been conducted with plain and finned heat sinks each for several times with a certain gap up to the highest heat flux and the ageing problem have been examined for the influence in heat transfer performance and heat sink surface characteristics. The main reasons for ageing have been identified as oxidation and deposition and chrome plating has been proved to be a possible solution to alleviate the ageing problem. Also the significance of accounting for ageing effect in reporting for research results and designing pool boiling heat sinks have been discussed.