Numerical investigation of Merkel simplifying assumptions for the thermal analysis of forced draft wet cooling tower

Abstract

The heat-mass transfer in the packing zone of a forced draft wet cooling tower is investigated in the present study by two different one-dimensional models like Merkel model and the Klimanek & Bialecki model. Merkel's model is based on Merkel simplifying assumptions, unlike Klimanek & Bialecki's model. After the ordinary differential equations, systems are derived for both the models, then, these equations systems are solved numerically by the Runge-Kutta method, to carry out, the water and the air temperatures, the humidity, and also other proprieties variation along the packing zone. Finally, after we have compared the results of both models with the same experimental data of a laboratory cooling tower. It has been noticed that both models are very accurate; however, the differences between the results of Merkel and Klimanek & Bialecki models with the experimental data at the packing outlet, are respectively about 0.14°C and 0.67°C for the water temperature, 0.07°C and 0.17°C for the air temperature. Furthermore, the relative humidity becomes 0.89% and 0.18% less in Merkel and Klimanek & Bialecki models respectively as compared to the experimental data for the same operating condition. Finally, it is noticed that the Merkel model is advantageous because of its easier equation derivation and is slightly more accurate than the Klimanek & Bialecki model.