Effects of Non-Condensable Gases on Heat Transfer Performance of Loop Thermosyphon for CPU Cooling

Abstract

We have developed a loop thermosyphon for cooling electronics devices. Non-condensable gases (NCG) in a loop thermosyphon increase by leakage from outside, release of the gas dissolved in the refrigerant, and chemical reaction in the inside. Hence, it is necessary to know how the heat transfer performance changes when the amount of NCG in a loop thermosyphon increases. The effect of NCG's amount was measured for each component of the loop thermosyphon while changing the amount of heat input. The overall thermal resistance of a loop thermosyphon increased with the amount of NCG. The thermal resistance of the condensing part particularly increased with the NCG. The effect of NCG on the boiling part should be considered only by steam temperature which was raised by increase in the amount of NCG. The thermal resistance of the air cooling part is not affected by NCG, but the temperature difference of the air cooling part becomes smaller because heat-leakage increases with steam temperature.