Empirical correlation of cooling efficiency and transport phenomena of direct evaporative cooler

Direct evaporative cooling (DEC) uses evaporating water, combined with a wetted medium to cool the temperature of air as it passes through. Heat is removed from the surrounding air in the vaporization of the water by passing through or around a wetted surface. The process approximates the adiabatic-saturation process and the path lies on a constant wet-bulb temperature which is a constant enthalpy line. This paper suspects the relationship between system parameters and cooling efficiency. Effects of three system parameters (speed of frontal air, the dry-bulb temperature of frontal air, and the temperature of the incoming water) on cooling performance were evaluated. Each parameter was varied while holding all other variables constant, and data was collected using several different levels of each parameter. The general relationship between each parameter and efficiency was determined by graphing the data collected and observing trends. Reasons that lead to the tendencies of the curves in the graphs have been explained in detail. The empirical correlation between supply frontal air velocity and cooling efficiency for DEC system in a typical applied environment was established and verified by experiment data. The analysis shows within certain ranges, DEC cooling efficiency increases with frontal air dry-bulb temperature; decreases with frontal air velocity and incoming water temperature correspondingly.