Evaluation of the optimum pressures of gas turbines based on energy and exergy analyses

The irreversible Brayton cycle is usually used in gas turbine-based power plants. In this study, energy and exergy analysis has been performed for an irreversible Brayton cycle with a regenerator, reheater, and intercooler for the first time. The influence of different parameters such as the efficiency of the cycle's components is examined based on the first and the second laws of thermodynamics. The lost exergy in different components and the total exergy loss of the irreversible Brayton cycle are calculated for various conditions. The optimum pressure of the intercooler and the reheater is obtained for different cases. An irreversible Brayton cycle with regenerator, reheater, and intercooler is simulated in engineering equation solver software and the optimum pressure in each simulation is determined based on the first and the second laws of thermodynamics. Furthermore, the obtained optimum pressures are compared with the geometric mean of the low and the high pressure of the cycle in each simulation. The results show that the optimum pressure of the intercooler changes between 0.69 P P mean max and 0.98 P P mean max based on exergy analyses and changes between 0.98 P P mean max and 2.97 P P mean max based on energy analyses.