Evaporative cooling performance resulting from changes in water temperature

Three trials were conducted to determine the effect of water temperature on the performance of an evaporative cooling system. A small, self-contained “pad and fan” evaporative cooling system with a 1.3 ¥ 1.3 m (4 ¥ 4 ft) cross-section tunnel and a 0.9 ¥ 0.9 m (3 ¥ 3 ft) area pad was used for the test. Inlet air temperatures were 32, 35, and 38°C (90, 95, and 100°F). Water temperatures were 10 to 50°C (50 to 120°F) in 5.5°C (10°F) increments. Results showed that for each inlet-air temperature tested, the performance of the evaporative cooling system worsened as the water temperature increased. Over the range of treatments, dry-bulb temperature and relative humidity of the conditioned air increased over 2.2°C (4.0°F) and over 3.2%, respectively; the amount of water evaporated increased 73%; and the system efficiency declined 16.1%. The results support the conclusion that as the water temperature increases, the performance of evaporative cooling systems decreases.