Phase change cooling with evaporative condenser at data centers

Chiller-less data centers are energy efficient but only available in cold climate regions. This is due to high thermal resistance between heat sink and ultimate sink (ambient air) and heat dissipation rate relies on environment temperature. The purpose of this study is to extend availability of chillerless data center with a rack rear-door heat exchanger in warm climate regions. Evaporative condensers with natural/forced circulation cooling system by phase change heat transfer were experimentally studied to reduce thermal resistance at the condenser. Furthermore, impact of heat exchanger configuration and effect of atomized water spray were studied. Experiment verified that thermal resistance reduction in the external side of the heat exchanger by water vaporization failed to appear when horizontal heat exchanger configuration was used. Approximately 40% reduction of thermal resistance of condenser was observed on the data center test facility by spray of atomized water particles, produced by pneumatic spray nozzle, on the vertical heat exchanger at wet bulb temperature of 15°C. The results suggest that energy savings can be achieved by the appropriate evaporative condenser usage that reduces running cost of data centers in warm climate regions.