A study of fouling and its effects on the performance of counter flow wet cooling towers

Abstract

Fouling of fills is one of the most important factors affecting cooling tower thermal performance, reducing the effectiveness and capability of the cooling tower. In this paper, experimental data on fill fouling that have been reported in the literature are used to develop a fouling model. The model predicts the decrease in the fill performance index, n_F, with the growth of fouling on fill materials. The authenticity of the fouling model is validated by experimental data. The fouling model, in conjunction with a detailed model of a counterflow wet cooling tower, is used to study the effect of fouling on cooling tower effectiveness and water outlet temperature. The models are used for studying the performance of small and medium-sized cooling towers under different air inlet wet-bulb temperatures. The results demonstrate that fouling of fills negates any gains in cooling tower performance that result from decreasing values of air inlet wet-bulb temperature. Furthermore, it is demonstrated that this effect is more pronounced in medium-sized cooling towers compared with small towers. Water outlet temperature decreases by 23.5 per cent in the case of small cooling towers, compared with an 18.3 per cent decrease for medium-sized towers under similar operating conditions.