Immersed Cooling of Electronics

Abstract: This master thesis is supported by Ericsson to conduct research on immersed liquid cooling of electronics. By this technology, the liquid will be in direct contact with the electronics. The research begins with investigations in industrial background, literature review and theory in heat transfer. According to the knowledge from those investigations, different liquid cooling systems including indirect, direct and immersed liquid cooling systems are introduced. The experiment consists of three parts: air cooling, single-phase and two-phase liquid cooling. Those three parts are with the same test board with adjustable heat resources in the same geometry. In the first part, an air flow channel is used for testing air cooling, by which immersed liquid cooling can be compared to traditional technology. In the second part, an immersed liquid cooling system is designed and constructed with detailed explanation. Liquid NovecTM 7200 is used as working liquid. In the third part, a huge number of data has been collected during the whole process of boiling, through which a boiling curve for NovecTM 7200 has been acquired. Then comparisons between those three technologies have been made. The feasibility of immersed liquid cooling on an industrial scale has also been discussed. Based on the experiments and analyses, a careful conclusion that electronics with liquid cooling has a larger heat flux limit than with today’s air cooling but with some practical problems can be drawn.