Experimental optimization of a Regenerative Indirect Evaporative Cooler: Effects of working air ratio, pump control strategy, water temperature, and ambient conditions.

Indirect Evaporative Cooling (IEC) is an eco-friendly method to reduce air temperature without adding moisture. This study presents an experimental investigation of a Regenerative Indirect Evaporative Cooler (RIEC) in which cooling efficiency is enhanced by redirecting a portion of the cooled air from the dry compartment back to the wet compartment. The effects of various factors on RIEC performance were examined, including the working air ratio (WR ratio), pump control strategy, water temperature, dry bulb temperature, and supply air flow rate. Results demonstrate that an optimum WR ratio of 0.37 was identified for enhanced cooling performance, while a novel pump cycling strategy (2-minutes on/60-minutes off) was found to reduce power consumption by 32.3 % compared to continuous pump operation while improving outlet air temperature reduction by 53 % relative to conventional continuous operation. Room-temperature water was determined to be more energy-efficient than chilled water, and maximum wet bulb effectiveness of 97.66 % was achieved at intermediate supply air flow rates. These findings provide valuable insights for optimizing RIEC systems across various climatic conditions and practical applications.