Author : Abdul Hadi N. Khalifa

Merkel theory was derivative in this work for a counter flow induced draught cooling tower with some simplifications. The governing equation was solved by an iterative method. The tower was divided into 100 horizontal elements, the temperature difference in each element was 0.1 K. Mass, energy and exergy balances were evaluated for each element using Engineering Equation Solver (EES) software. For such tower, it was found that the ratio of mass flow rate of water to that for air (L/G) is in the range of 1.25 to 1.5. Since the exergy of air is consumed to destroy the exergy of water, then, more exergy destruction gives higher exergy efficiency for cooling tower. As the moisture content of the air increases the air chemical exergy increases, on the another hand, as air temperature approaches to water temperature air thermal exergy tend to reduce. And finally, Merkel assumption, that state that saturated air leaving cooling tower, gives curvature path for saturation process instead of a straight line.

Keywords: Cooling Tower, Exergy, Heat and Mass Transfer, Merkel theory , exergy destruction, Thermal Performance.

Article published in International Journal of Current Engineering and Technology, Vol.5, No.4 (Aug-2015)