Two-phase liquid cooling system for electronics, part 1: Pump-driven loop

An experimental study to analyse the thermal performance of a two-phase pump-driven loop for electronics cooling is presented, with the target application being a telecommunications equipment shelf having multiple circuit pack cards each dissipating several hundred Watts of power. The upward flow boiling heat transfer and pressure drop of R134a within an evaporator prototype fabricated with 18 individual microcooling zones to cool multiple electronics heat sources was investigated. The electronic heat sources were emulated by multiple copper heater blocks with embedded cartridge heaters, where each heat source was capable of dissipating more than 100 W, for a total power dissipation larger than 1800 W. Experimental results demonstrated the best cooling capability at a mass flow rate of 140 kg/h, uniform heat load of 1800 W to the 18 microcooling zones, system pressure of 600 kPa and inlet subcooling of 2 K in which the temperature difference between the evaporator and coolant inlet was 7.1 K with a uniform flow distribution within the evaporator.