Finite-time exergoeconomic performance of a real intercooled regenerated gas turbine cogeneration plant. Part 2: heat conductance distribution and pressure ratio optimization

Abstract

Finite-time thermodynamics is applied to establish a real intercooled regenerated gas turbine cogeneration plant model in Part 1 of this article and the profit rate performance of the plant is researched using finite-time exergoeconomic analysis. In this part, the optimization of finite-time exergoeconomic performance of the plant is performed by optimizing the intercooling pressure ratio and the heat conductance distributions among the hot-, cold- and consumer-side heat exchangers, the intercooler and the regenerator together, and it is found that the optimal heat conductance distribution of the regenerator is zero. When the heat conductance distribution of the regenerator is fixed, the results show that there exists an optimal intercooling pressure ratio and a group of optimal heat conductance distributions among the other four heat exchangers, which leads to a maximum dimensionless profit rate for the fixed total pressure ratio. When the total pressure ratio is variable, a double-maximum dimensionless profit rate is obtained. The characteristics of the double-maximum dimensionless profit rate, the corresponding exergetic efficiency, heat conductance distributions and total pressure ratio versus some main design parameters are analyzed in detail. Finally, it is found that the dimensionless profit rate has a thrice-maximum value with respect to the thermal capacitance rate matching between the working fluid and the heat reservoir.