The optimum pressure for working fluid in feed water heaters of steam power plants

The aim of this study is to find the optimal water pressure and percentage of supply vapour in the feed water heaters (fwhs) of steam power plants, such that they maximize the thermal efficiency of the Rankine cycle within pre-specified values of minimum and maximum pressures of the thermodynamic cycle. Thermal efficiency is defined as a function of unknown variables (fluid pressure and vapour percentage of each fwh), and it is maximized numerically using the nonlinear constraint optimization method. Precise values of enthalpy are used in computations of thermal efficiency during the nonlinear optimization process. The enthalpy and entropy values at different points of the thermodynamic cycle are calculated utilizing the industrial formulation of IAPWS-IF97.