Thermoeconomic optimization of scroll-based organic rankine cycles with various working fluids

Abstract

In this study, thermoeconomic optimization method is applied to an organic Rankine cycle system to evaluate the cost of the system and net generated revenue as a function of exergy efficiency to be able to generate most economical electricity, depending on market conditions and fuel prices. Thermoeconomic optimization can serve as one of the most important stages in the design procedure which, for defined boundary conditions, makes it possible to find the optimal values of independent variables. The values that minimize or maximize the chosen optimization criteria are considered to be optimal in this case. It may be the annual net profit, time of return of investment, or any other economic profitability criterion. Here, the cost per unit of net electric power generated by the cycle is chosen as the primary measure of the performance of the system. It is considered to be the most universal optimization criterion since the other two mentioned are dependent on price at which electricity can be sold. This price may vary depending on the country and the type of application. It is found that best possible solutions can be obtained for the exergy efficiency of approximately 55 % in terms of cost of the system and net revenue.