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In optimization of thermodynamic cycles, it is appropriate for the economic and environmental aspects to be considered simultaneously. The sum of the fuel and investment cost flowrates is known as thermoeconomic objective function. A new objective function, known as a thermoenvironomic objective function, is obtained by integrating the environmental impacts, which should be defined and expressed in terms of cost, and thermoeconomic objective function. The objective of this paper is to study the effect of air preheater (APH) in the thermodynamic cycles by considering environmental impacts. In order to perform this, four simple thermodynamic cycles are selected and economic and environmental aspects are optimized. All considered thermodynamic cycles produce 30 MW of electricity and two of them, which are cogeneration systems, produce 18 kg/s of saturated steam at 20 bar, too. For optimization of these cycles, a code has been developed in MATLAB based on the real coding and optimal solutions have been obtained. The results show that the existence of APH increases exergetic efficiency of the cycles and the environmental impacts cost flowrate but decreases the total cost flowrate. Also, in the cycles without APH, the optimum values of decision variables corresponding to thermoeconomic and thermoenvironomic objective functions do not change considerably, while in the cycles with APH, they change noticeably.

An exergetic optimization is developed to determine the optimal performance and design parameters of a solar photovoltaic (PV) array. A detailed energy and exergy analysis is carried out to evaluate the electrical performance, exergy destruction components, and exergy efficiency of a typical PV array. The exergy efficiency of a PV array obtained in this paper is a function of climatic, operating, and design parameters such as ambient temperature, solar radiation intensity, PV array temperature, overall heat loss coefficient, open-circuit voltage, short-circuit current, maximum power point voltage, maximum power point current, and PV array area. A computer simulation program is also developed to estimate the electrical and operating parameters of a PV array. The results of numerical simulation are in good agreement with the experimental measurements noted in the previous literature. Finally, exergetic optimization has been carried out under given climatic, operating, and design parameters. The optimized values of the PV array temperature, the PV array area, and the maximum exergy efficiency have been found. Parametric studies have been also carried out.