Analysis of Dehumidification Effects on Cooling Capacity of an Evaporative Cooler

Abstract

In this study, effect of desiccant wheel, heat exchanger and cooling coil will be evaluated on decreasing the wet bulb temperature of entering air to cooling tower and decreasing the outlet cold water temperature. For this purpose, change effect of desiccant wheel parameters will be investigated on wet bulb temperature of outlet air from heat exchanger. After that, optimum parameters and minimum wet bulb temperature will be selected. Then, outlet cold water temperature will be achieved for various cooling coil surface temperature with definition of by pass factor and also by using optimum desiccant wheel parameters and entrance air wet bulb temperature to tower related to cooling coil surface temperature. To calculate wet bulb temperature, a mathematical model will be used that shows physical properties of air. After that a nomograph will be used to predict effect of decrease of entrance air wet bulb temperature on reducing the outlet water temperature and it will be done for several cities in Iran. At the end, an equation will be used to calculate required water to air mass flow rate for each outlet cold water temperature. With considering of known circulating water mass flow rate, required air for tower would be calculated and suitable desiccant wheel can be selected.

Keywords

• desiccant wheel
• wet cooling tower
• wet bulb temperature
• cooling coil
• heat exchanger