Experimental and Theoretical Study of Dew Point Evaporative Cooling System Suitable for Erbil Climate

Abstract

Evaporative cooling is an efficient natural process. In this study a dew point evaporative cooling system has been designed, and constructed. A dew point evaporative cooler comprised of combination of multi-stage sensible water to air heat exchangers and evaporative media. In this study the performance of the dew point evaporative cooling system is studied as theoretical and experimental work which is carried out at Erbil Polytechnic University. This work includes the estimation of the effect of impact factors on the system. Based on the conducted experimental and numerical analysis, it is concluded that the performance of the cooling system significantly depends on the; circulating air mass flow rate to the pad, water spray mass flow rate, dry bulb temperature, humidity ratio of incoming air and using return air when evaporative media is having insufficient air. The performance of the system depends on both the effectiveness of water to air heat exchangers and evaporative media. The wet bulb effectiveness of the system is ranged from (45% to 73%) for a single stage. Using return air from cooled zone improves the wet bulb effectiveness. Exhaust humid air can be used in economizer for precooling incoming air. The economizer improves the wet bulb effectiveness of the system from (73% to 93%) with using return air from cooled zone. The ASHRAE guidelines for thermal comfort recommend (20℃ to 24℃) in the winter and (23℃ to 27℃) in the summer and a relative humidity (RH) of (30% to 60%) is recommended.