Modeling of Geothermal Water Cooling System

Abstract

Cross flow mechanical cooling towers are widely used in the south region of Tunisia for cooling geothermal water in agriculture and domestic ends. These towers are sized empirically and present several problems in regard to operation and electrical energy consumption. The objective of this paper is to study the thermal behavior of this type of cooling towers, through a developed mathematical model, considering the variation of the water mass flow rate inside the tower. The analysis of water and air temperatures distribution along the cooling tower had underlined the negative convection phenomenon at a certain height of the tower. This analysis has shown also that the difference in water temperature between the inlet and the outlet of the tower is much higher than the one of air due to the dominance of the evaporative potential compared to the convective one.
In addition, the variations of the air humidity along the cooling tower and the quantity of evaporated water had been investigated. The loss of water by evaporation is found to be not negligible; in fact it presents 5.1% of the total quantity of water feeding the cooling tower. More effort will be done to decrease this amount due to the lack of water in the south of Tunisia.