Effect of change factors on evaporation loss based on cold end system in natural draft counter-flow wet cooling towers

The cooling process of circulating water in the NDWCTs is an extremely important process, which is achieved by the contact heat dissipation and evaporation heat dissipation in the NDWCT. For the NDWCTs, the water loss of cooling tower mainly includes evaporation loss, windage loss and blowdown loss. Evaporation loss makes up most of the water loss at thermal power plants. For this reason, the study on the prediction of evaporation loss in the NDWCTs lay a theoretical foundation for the thermal power plant to decrease the emission and save water. In the power industry, water is often used as a heat transfer medium to dissipate heat, and in many areas, water has become a scarce resource. How to take measures to reduce or recover water consumption of thermal power plants, many scholars have paid attention to this issue, and achieved remarkable results (Yuan et al., 2019; Bustamante et al., 2016; Wei et al., 2018; Saidi et al., 2010). The application of the direct air-cooled technology in power plants is a key measure to achieve water conservation. Factors such as wind direction, fan performance and blade installation angle have a great influence on the cooling capacity of a direct air-cooled system (Yang et al., 2011; Zhang et al., 2019a, 2019b; Zhang et al,. 2018a, 2018b). However, the direct air-cooled systems account for a small part of the cooling towers. Most cooling methods in thermal power plants are wet cooling. Several mathematical models for predicting evaporation loss had been established in the mechanical wet cooling towers. Kairouani constructed a mathematical model for the numerical prediction of the performance of cross flow cooling towers and used this model to predict the thermal behavior of six cooling towers located in the South of Tunisia. It was found that the actual water losses by evaporation represent 4% of the total water flow rate, which corresponds to 106 m per year (Kairouani et al., 2004). Based on ASHRAE’s rule of thumb Qureshi set an empirical formula, and it could accurately predict the evaporation loss of cooling tower (Qureshi et al., 2006; Qureshi et al., 2007). Effect of change factors on evaporation loss based on cold end system in natural draft counter-flow wet cooling towers