Modeling an Evaporative Cooling System to Improve Gas Turbines Performance

Abstract

Evaporative cooling are systems commonly used in thermoelectric plants to cool the air at gas turbines inlet, improving the performance of these engines. In adiabatic saturator, or ideal evaporative cooling, the water-air equilibrium temperature, that occurs when the process effectiveness is maximum, depends only on the atmospheric air properties. However, other factors such as, the water temperature that supplies the evaporative cooling and the ratio between the mass flows of water and air, also affect the equilibrium conditions of the system. This work presents three methodologies to calculate the air temperature in equilibrium state, considering all the factors mentioned. The methodologies were implemented in a computer program written in Fortran. In all cases tested, the results obtained by the three models showed high convergence. As an example, for seventy different sets of inputs, the absolute and relative differences of the results were below 0.3236 °C and 1.2480 %, respectively. A statistical study, also on this sample of results, revealed that for a confidence level of 99%, the hypothesis of the equivalence between the methods cannot be not rejected.