Performance analysis and multi-objective optimization of mechanical draft wet cooling towers based on water saving, plume and cooling characteristics

To establish an efficient and clean cooling tower, a mechanical draft wet cooling tower (MDWCT) with the condensation plume module is studied. A 3D mathematical model is conducted, the width of the channel within the module is the main research variable, while the outlet water temperature, water saving rate, and plume are the main outputs. Three types of outputs are optimized by the NSGA-II multi-objective optimization algorithms, and the entropy weight TOPSIS method is used to find the optimization operating point. Results show that increasing the width of the wet channel is not conducive to plume abatement and water conservation, but is beneficial for reducing the outlet water temperature. However, increasing the width of dry channels results in an opposite phenomenon, and the outlet water temperature and water saving rate are more sensitive to variation in the dimension of the dry channel. When the width of dry channels enhances from 0.01 m to 0.02 m, the water saving rate average grows by 4.68% with the increase accounting for approximately 72.11%, and the outlet water temperature ascends by 0.62 °C. The three optimization output values are 23.62 °C, 16.31%, and 0.018 kg/kg, and the corresponding wet and dry channels width are 0.03 m and 0.02 m respectively.