Investigation of the simultaneous effect of fouling and ambient conditions on cooling performance and water consumption of a wet cooling tower

Abstract

The cooling performance and water consumption of the wet cooling tower are two important parameters that must be balanced to achieve the optimum performance of this industrial component in its operating condition. The performance of the wet cooling towers can be analyzed by the thermodynamic models. On the other hand, fouling can drastically affect the cooling tower performance. In the present research, a thermodynamic model is developed and validated with numerical and experimental results in order to investigate the wet cooling tower's water consumption and cooling performance under various weather conditions. The model includes an accurate cooling tower model, considering the buoyancy force and droplets evaporation in the rain and spray zones. To achieve accurate results, an optimization algorithm is also utilized to solve the equations. This model was then applied to analyze the water consumption and cooling performance of a small cooling tower during the hottest months of Iran (July/August) in Ahvaz, Tabriz, and Yazd with different climate conditions. The non-dimensional parameter of the fill performance index (ηF) was used to describe the fouling in the packing. So, considering the simultaneous effects of the buoyancy force and droplet evaporation in the rain and spray zones and fouling in packing in the developed model, with utilizing a new and accurate method to solve the model's equation to analyze the performance of the wet cooling towers under different conditions, are the novelty of this study. Based on the results, a rise in fouling decreases the fill performance index. A decline in the fill performance index from 2.4 to 1.2 increases the monthly average of the cooling tower outlet water temperature from 24.24, 21.21, and 21.19 °C to 25.94, 24.14, and 24.11 °C in Ahvaz, Tabriz, and Yazd, respectively, while the monthly water consumption decreases from 1.74, 1.87, and 2.22 m3h to 0.99, 1.10, and 1.29 m3h in the mentioned cities, respectively. The maximum outlet water temperature was observed in case ηF=1.2, while the maximum water consumption occurred in ηF=2.4. So, ambient conditions and fouling simultaneously affect the performance of the cooling tower, which is well predicted by the suggested model.