Two-phase liquid cooling system for electronics, part 2: Air-cooled condenser

An experimental study investigating the thermal performance of a two-phase thermosyphon for electronics cooling is presented in this article. Two-phase cooling implemented using a gravity-driven thermosyphon-based system represents an efficient solution for dissipating high power densities compared to traditional air-cooling approaches, allowing for increased reliability and reduced power consumption. The thermosyphon-based system consists of an evaporator with 18 individual microcooling zones connected via riser and downcomer tubes to an air-cooled condenser. Experiments were carried out with working fluid R134a for filling ratios ranging from 45% to 65%, heat loads from 102 W to 1841 W and air flow rates from 516 m3/h to 1404 m3/h. Robust thermal performance was observed for the entire range of operating conditions. In particular, at the optimum filling ratio of 50%, minimum air flow rate of 516 m3/h and uniform heat load of 1841 W, the temperature difference between the evaporator and ambient air was less than 20 K with a COP of 102, while at the highest fan speed of 1404 m3/h this temperature difference was reduced to 8.9 K, with a reasonable COP of 11. The test results show the high efficiency of the current hybrid air- and liquid-based cooling technology for removing heat from electronics to the ambient.