Numerical and experimental study on performance of seawater cooling towers based on a comprehensive coupling model

Abstract

A comprehensive model composed of spray zone, rain zone and packing was established to investigate the thermal characteristics of the seawater cooling tower. To achieve this goal, a comprehensive wet cooling tower model is integrated with an exergy analysis. C language programming was used to numerically simulate the water–gas two-phase heat-moisture exchange process and parameter distribution in the seawater cooling tower under different salinity conditions. The research shows that the heat dissipation at the top of the tower is largest, which is about 1.7 times that of the bottom of the tower; the exergy loss decreases first and then increases gradually from the bottom of the tower, and reaches the maximum at the top of the tower. The increase in salinity leads to an increase in total exergy loss and a decrease in exergy efficiency. Compared to freshwater, as the salinity increases from 35 g/kg to 105 g/kg, the total water exergy loss increases by 5.86 % to 15.62 %, and the exergy efficiency decreases by 3.52 % to 10.72 %, the cooling efficiency decreases by 2.29 % to 7.59 % and the amount of water replenished decreases by 5.07 % to 16.06 %. Furthermore, the influencing factors of the heat and mass transfer characteristics in the seawater packed tower were optimized, and the combination of working conditions parameters with the highest cooling efficiency, the lowest exergy loss and the requirement of heat dissipation was obtained. This study provides a theoretical basis for predicting the performance of cooling towers accurately and a guidance for optimizing design of cooling towers.