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An irreversible hybrid solid oxide fuel cell (SOFC)-Brayton heat engine system is taken into account in this study. Ecological based thermoenvironmental function is considered to assess the performance of the system as well as the power, exergy destruction, energy and exergy efficiencies. This function enables someone to determine environmental impact of any thermal cycle. Optimum operating conditions for all investigated parameters are obtained. Results are presented numerically and discussed. Some important results are; maximum power density of the hybrid system is 15260.9 (W m−2) at i = 17,000 (A m−2), maximum energy efficiency of the hybrid system is 0.841 at i = 7200 (A m−2), exergy efficiency of the hybrid system is 0.676 at i = 5200 (A m−2) and ecological based thermoenvironmental function density of the hybrid system reaches maximum value at i = 5800 (A m−2) and it is equal to 0.00603 (W m pts−1 m2). Finally, environmental friendly and efficient operation conditions, if ≤ i ≤ iP, is suggested for the hybrid system.

An irreversible hybrid molten carbonate fuel cell-Braysson heat engine is taken into account. Basic thermodynamics parameters including power output, efficiency and exergy destruction rate are considered. In addition ecological function and new criteria, which is based on ecological function, for heat engines called as modified ecological function is suggested. Optimum conditions for mentioned parameters above are determined. Numerical results are obtained and plotted. Finally, results are discussed.

In this study, a novel combined extended-advanced exergy analysis method is developed for assessing thermodynamic systems. The method is established by combining extended exergy analysis with advanced exergy analysis and the so-called extended-advanced exergy analysis. The methodology used in the novel analysis method is different from only extended exergy analysis and only advanced exergy analysis, but the criteria are the same to reach the goal. This proposed method is applied to a gas turbine system as a case study to show its variability. The gas turbine system considered consists of a combustion chamber, a compressor and turbine units. The conventional (Fuel-Product approach), advanced and extended exergy analyses are separately applied to the case study system for the comparison with the novel combined extended-advanced exergy analysis. It is seen that the combined extended-advanced exergy analysis results of the case study are not exactly the same with the advanced and extended exergy analyses’ results. The reason for this is its comprehensive joint of various thermodynamic analysis methodologies integrating all materials, capital, labor, energy and environmental effect instead of the relation between components and their improvement potentials in one analysis. But it is assessed that the novel analysis tool is able to apply all of those analyses into one simple methodology. The exergy efficiencies of the case study are 28% and 31% by considering the conventional and extended exergy analyses, respectively. This means that all input parameters including labor, capital and environment are used with better efficiency. Also, the exogenous exergy destruction rate (159 kW) is higher for the combined extended-advanced exergy analysis (384 kW). This shows that the relations between other components are increased for the turbine. Another important change is shown in avoidable exogenous exergy destruction rate for the turbine, increasing from 374 kW to 833 kW. This new combined method is useful to those, who wish to apply advanced and extended exergy analyses through a new practical assessment way.

In the present study, environmental impact analysis is used for the optimization to an actual heat engine. Four new thermoenvironmental evaluation criteria called as thermoenvironmental function, ecological based thermoenvironmental function, ecologicoenvironmental function and finite time exergoenvironmental criteria are developed and compared with the each other. Ecologicoenvironmental function is used to determine environmental impact at the maximum ecological function. It is defined as the most suitable criteria for an actual heat engine. Because, it has lower irreversibilities compared with others, its work output is equal to 90% of the maximum work and 60% energy efficiency at the optimum point and exergy destruction is lower than others at the optimum point.

An irreversible heat pump was investigated via entransy analysis and performance criteria. In the analyses, two different convective heat transfer laws were applied to the considered system: the Newton and Dulong–Petit heat transfer laws. The irreversibilities in the system are the result of a finite heat transfer rate, a heat leak and internal irreversibilities, including friction, turbulence etc. In this study, a thermodynamic analysis was performed in detail, and the numerical solutions were used for the conducted analysis. The maximum entransy dissipation (critical points) ranges from 18436.7 kW K to 18855.3 kW K according to y for Newton’s law; however, there is no maximum point for the Dulon–Petit law. It can be concluded from this study that entransy should be used among the basic thermodynamic criteria.

This paper deals with the performance assessment of an electricity generation facility located in the Eskisehir Industry Estate Zone in Turkey using advanced exergy analysis method. The exergy efficiency of the system is determined to be 40.2% while the total exergy destruction rate of the system is calculated to be 78.242 MW. The exergy destruction rate within the facility’s components is divided into four parts, namely endogenous, exogenous, avoidable and unavoidable exergy destruction rates. Through this analysis, the improvement potentials of both the components and the overall system along with the interactions between the components are deducted based on the actual operational data. The analysis indicates that the combustion chamber, the high pressure steam turbine and the condenser have high improvement potentials. The relations between the components are weak because of the ratio of the endogenous exergy rates of 70%. The improvement potential of the system is 38%. It may be concluded that one should focus on the gas turbine and combustion chamber for improving the system, being the most important components of the system.

This paper presents conventional and advanced exergoenvironmental analyses of an electricity generation facility located in the Eskisehir Industry Estate Zone, Turkey. This facility consists of gas turbine and steam cycles, which generate electrical power of approximately 37 MW and 18 MW, respectively. Exergy efficiency of the system is 0.402 and exergy destruction rate of the system is 78.242 MW. Unit exergy cost of electrical power generated by the system is 25.66 $/GJ and total exergoeconomic factor of the system is 0.279. Conventional exergy analysis method was applied to the system first. Next, exergy environmental impacts of exergy destruction rate within the facility’s components were divided into four parts generally, as endogenous, exogenous, avoidable and unavoidable environmental impact of exergy destruction rate. Through this analysis, improvement potential of the environmental impacts of the components and the overall system and the environmental relations between the components were then determined. Finally, exergoenvironmental factor was determined as 0.277 and environmental impact of the electricity was 8.472 (Pts/h). The system has 33% development potential for environmental impacts while its components have weak relations because of big endogenous parts of environmental impacts (80%). It may be concluded that advanced exergoenvironmental analysis indicated that priority should be given to the GT and CC, while defining the improvement strategies.

Distributed generation as a viable solution to the energy crisis has gained popularity in recent years due to reduced transmission losses and improved efficiency. In this study, nine scenarios are considered to analyze and evaluate a cogeneration system in various conditions. The cogeneration system that includes a gas turbine, absorption chillers, boilers, and heat exchangers is modeled in EES software. The system is studied in multiple scenarios. Values of energy efficiency (EE), used energy (UE), and utility fuel ratio (UFR) are calculated to assess the system. In addition, the amount of CO2 production is also investigated for each of the scenarios. It is found that the system used in scenario No. 5 which consists of two absorption chillers installed in series, with UFR of 45325.50 kJ/kg has the optimum performance in terms of simultaneous electricity and cooling generation. For electricity and heating generation, scenario No. 7 in which heat can be completely recovered, with UFR of 39541.90 kJ/kg is the optimum configuration. It is monitored that scenario No. 1 and scenario No. 6 have the highest amount of carbon dioxide production among the studied scenarios, 88.18 kg/s.