Optimization of Water Consumption in Hybrid Evaporative Cooling Air Conditioning Systems for Data Center Cooling Applications

In the light of its potential to reduce energy consumption when coupled to the condenser of existing vapor compression systems, evaporative cooling technology still faces questions relating to its water consumption pattern and the effect of water quality on its performance. This paper presents an experimental investigation of the water consumption characteristics in a split air-conditioning system employing evaporative precooling of air flowing over the condenser coils. The effect of the cooling pad thickness on the coefficient of performance of the system is investigated by varying the pad thickness from 5 to 15 cm in step size of 5 cm. Condition of the exit air from the pad shows that evaporative cooling can be employed as a standalone method for cooling of data centers, with adequate humidity control systems in place. Results obtained on water consumption shows that the volume of water consumed does not increase proportionally with time, rather it increases by a factor of 1.8, 2.5, and 3.2, for 2, 3, and 4 hours of operation respectively, relative to 1hour of operation. Two parameters; salinity and turbidity were used to study the effect of water quality on the evaporative cooling process. Additionally, a method of optimizing the pump operation is introduced in this paper. Running the pump intermittently could cut the energy consumed by the water pump in such a hybrid system by up to 20%.