Increasing evaporative cooler efficiency by controlling water pump run and off times

Abstract

One of the major problems with using the evaporative coolers is reduction in cooling capacity and cooling efficiency in high humidities and insufficient cooling capacity at high temperatures. In this paper a method is introduced which increases the cooling capacity, especially at higher temperatures and also it could maintain the cooler efficiency in high humidity weather. In this method the water pump Instead of operate continuously, it works intermittently and a control unit with its sensors control the operation time by tracing changes in outlet air or pads condition. In evaporative coolers by switching off the water pump, though a slow increase in the outlet air temperature is expected, the temperature falls gradually which means the cooler cools the air down more efficiently. This phenomenon could be attributed to pads lower temperature due to evaporation of some portion of water on pad fibers. This method by using this missing character of the evaporative coolers, makes the cooler perform the same as the two-stage indirect/direct evaporative cooler; in the two-stage cooler, the already cooled air entered to a direct evaporative cooler but with this device the entered air encounters with pads that have already been cooled.