Performance assessment of evaporative inlet air cooling impact on a 25  MW gas turbine plant under varying ambient temperatures

Abstract

Evaporative Cooling Systems (ECSs) are among cost‐effective and applied gas turbine compressor inlet air cooling systems to mitigate the negative impact of high ambient temperatures leading to performance degradation and lower power generation. Their cooling mechanism relies on the evaporation of water over porous media, such as cooling pads, to reduce the inlet air temperature. Effective management of both power generation and water consumption is essential due to economic considerations as well as environmental and climatic constraints. In this study, the performance of an ECS applied to a 25 MW gas turbine unit is investigated using real operational data from a power plant under varying ambient temperature conditions. The results showed that the average output power across the six gas turbine units increased by approximately 4.5% during the hours when the ECS was in operation. Furthermore, the intersection of the output power curves with and without ECS indicates the minimum inlet temperature at which the ECS becomes effective. The results also demonstrate that the effectiveness of ECS is strongly dependent on ambient temperature, with significantly higher performance at elevated temperatures. Finally, from a managing water consumption point of view, it can be concluded that the operation of the ECS between 13:00 and 18:00, when ambient temperatures are high, output power is minimal, and the ECS efficiency (temperature difference between inlet and outlet) is at its maximum, is recommended. Outside this time interval, although the system still increases output power, the significant water consumption makes it less worthwhile.