Performance of cooling tower in south of Tunisia

摘要

This paper presents a mathematical model for the numerical prediction of the performance of crossflow cooling towers. The mathematical model is based on the heat and mass transfer equations. The leading parameters are the Lewis number Le, the number of transfer units U, the percentage of water evaporation, the water losses and the tower efficiency. This model is used to predict the thermal behavior of six cooling towers located in the South of Tunisia. These towers are employed to decrease the temperature of geothermal water from 65℃ to 34℃ using a crossflow air. The total flow rate of water is 900 kg s~(-1) and that of dry air is 1840 kg s~(-1). Several experimental data have been collected on site, in order to adopt the mathematical model. The model has been used to predict the performance of cooling towers in terms of the meteorological conditions prevailing in the South of Tunisia. An optimal water loss quantity has been determined. On an annual basis, the actual water losses by evaporation represent 4% of the total water flow rate which correspond to 10~6 m~3 year~(-1). This represents the annual consumption of 20000 inhabitants.