Comparative study on the cooling performance of evaporative cooling systems using seawater and freshwater

This paper experimentally studies the cooling performance of seawater and freshwater for evaporative cooling of air. A low-speed wind tunnel was designed to test wet media evaporative cooling performance with seawater and freshwater, respectively. CELdek7060 media at thicknesses of 100 mm and 300 mm were used for studying. Sea salt was used to prepare different concentrations (i.e. 0.5, 1 and 1.5 times of seawater concentrations), and freshwater was the tap water. It was found that the pressure drop values caused by different concentrations of seawater and freshwater are close at the same water flow rate and the same thick medium. The cooling effectiveness of seawater is slightly lower than that of freshwater, and it decreases with the increase in seawater concentrations. For 100 mm and 300 mm media, the cooling effectiveness values of seawater (1 times seawater concentration) are 2.8-7% and 2.8-4.9% lower than that of freshwater, respectively, within the air speeds of 0.45-3.03 m s−1 at water flow rate of 62 l min−1 m−2. The empirical correlations of heat transfer coefficient for freshwater and different concentrations of seawater are developed. This study proves the feasibility of evaporative cooling using seawater, which is a significant benefit for evaporative cooling applied in coastal areas for saving freshwater.