Abstract:

In view of the disadvantages of wet evaporative cooling tower such as large water evaporation, large sewage discharge, and large fog plume in winter, this paper summarized the calculation formulas of air parameters in the air-water two-phase heat and mass transfer for the coil type, the filling type and composite type evaporative cooling tower. Combined with real-time inlet air temperature, moisture content and mass flow, the accurate calculation method of air temperature, moisture content, enthalpy and other parameters in the process of air-water heat and mass transfer were further clarified. The water evaporation rate, discharge rate and water saving amount were calculated at the same time period. The calculation results show that under the same inlet air relative humidity, the water evaporation rate and make-up rate corresponding to dry bulb temperature of 34℃ are 15% less than those corresponding to dry bulb temperature of 20℃. Under the same wet bulb temperature, the water evaporation rate and make-up water rate corresponding to dry bulb temperature of 34℃ increase by 48.8% than that corresponding to dry bulb temperature of 20℃. Therefore, the accurate calculation of air parameters in the evaporative cooling process, could avail the real-time calculation and regulation of evaporation rate, water make-up rate, discharge rate, and promote the optimization of water saving, plume abatement, energy saving and discharge reduction for wet evaporative cooling tower.

Key words: wet evaporative cooling tower, heat and mass transfer, water saving optimization, energy saving and discharge reduction, plume abatement characteristics