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SOFC-GT cycle coupled with a steam generator is investigated in this paper through the exergy analysis. Chemical and electrochemical simulation of SOFCs and thermodynamic and exergy models of other components are discussed and results are compared with a GT-Steam generator cycle. Based on simulation results Exergy efficiency of SOFC-GT- Steam generator is higher than conventional GT-Steam generator cycle. Furthermore parametric study is performed and results are presented. Parametric study shows that stack temperature and compressor pressure ratio can increase the efficiency but cell current density and TIT decrease the efficiency. Increase in steam pressure and decrease in Pinch Point, will increase the exergy efficiency.

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In this article the application of a turbo expander in a gas well has been studied technically economically and thermodynamically for the purpose of recycling the wasted exergy in a chock valve, reducing the gas pressure as well as generating huge amount of electrical power through a generator are among the advantages of applying an expansion turbine instead of chock valve. On the other hand this method is a clean method of energy production since no fuel is consumed for and no environmental pollution is caused through this method .In this thesis two software HYSYS and GAMS have been applied to calculate the productivity power in various pressure ranges and mass flow rate in different years of extractions when expansion turbine are used. Considering the necessary power of an infrastructure this system of calculation helps to determine the maximum life span of an expansion turbine in a gas well. This project is aimed at technical and economical planning and optimization of a mechanical package to recycle the pressure exergy of a gas well inlet chock valve in order to generate the electrical power both for the consumption of the infrastructure itself and for selling the extra amount.In administrating this project not only would the gas wells of the country become needless of electrical power but also the super flues amount at electricity could be sold to the national electricity network . Financial studies indicate that the capital returning period in this project for pressure range of 1850 – 4850 psig and mass flow rate of 21.2 kg/s at prices of 1600 $ per kilowatt hour and 0.12 $ per kilowatt hour for constructing a power station and the value of generated electricity respectively is estimated almost 3.5 years which economically appears really fascinating for the purpose of investment.

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This study covers the exergy analysis of the condensate stabilization unit of South Pars Gas Refinery. In this regard, the simulation of unit is carried out using HYSYS software to achieve all required data for exergy calculations. The final product is suitable for summer, as the Reid Vapor Pressure is achieved about 7 Psia. Afterwards, the exergy analysis is done using source-sink or stream-wise methods. Having analyzed all unit operations, it is shown that condensate tower and the associated heat exchanger have the most scope for energy improvement.

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This paper reviews the performance of various fluids in a coupled power and refrigeration cycle has been studied.exergy is used to assessment and optimize the energy system with more detailed useful information than energy analysis.indeed exergy analysis includes implement the first and second thermodynamic rules , and analysis of Energy and exergy various fluid of coupled power and refrigeration cycle EES software is used in this article. R134a ,R134a_mh , R12 ,R22 and R290 is the use of the working fluid in this paper. Based on the results, the most exergy efficiency and COP of the fluid is R290 and R12.

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In the present study, we investigated the thermal Tabriz power plant with capacity of 368 MW then analyze energy and exergy and thermodynamic models, components that have higher or lower efficiency loss in cycle identified and their need for the optimization of the most introduced. The energy analysis reveals that the condenser and boiler cycles 420.440MW and 146.268MW, respectively, are the highest energy losses. Thorough exergy analysis results indicate that the boiler with 473.861MW, a turbine with 34.534MW and condenser with 16.178MW, the maximum amount allocated to a thorough exergy destruction. Calculation results, the efficiency of the first and second cycles at rated load, respectively, 37.62% and 37.62% shows.

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Inappropriate effects of fossil fuels and conventional power generation systems on the environment as well as the growing interests in renewable energy systems have necessitated a sustainable energy system for the next decade. Hydrogen is the one of known new energy fuel for sustainability that could generate by PEM electrolyzer. The present study was aimed at optimization of functional parameters of PEM electrolyzer by energy and exergy analysis. For this, we have developed a electrochemical- mechanical model by MATLAB and analyze the energy and exergy efficiency. The results revealed that increased of pressure and temperature cause to close the exergy efficiency to energy efficiency and improve the system performance. The optimal pressure and temperature respectively are 3 atm and 273 K. Also, the voltage of system are raised by increasing the current density.

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Objective of this research is to Efficieny Enhancement and Polutant Gas Emission Reduction in a Benchmark Turbo-Compressor Gas Engine. Using Heat Recirculation of Flue Gas are studied and using a shell&tube and plate finn heat exchanger for simple gas cycle is considered and optimized. Thermodynamic modeling of the cycle is performed using energy and exergy analysis. Thermo-hydraulic modeling of the recuperators is performed using the modified heat transfer analysis and ε-NTU method in order to estimate the heat exchangers area, effectiveness and pressure drop. Optimization is considered as the multi-objective evolutionary algorithm in which one objective is maximizing the cycle exergetic efficiency, the second is minimizing the capital payback time of the recuperator and the other one is minimizing the Polutant Gas Emission for both of heat exchangers. A set of optimal solutions namely as the Pareto frontier are obtained and a final optimal solution are selected using the Bellman-Zadeh fuzzy decision-making approach, TOPSIS and LINMAP methods and the best solutions are reported. In final by comparing the heat exchangers, The best of heat exchanger was selected. Finally, by comparing optimal shell&tube and plate finn heat exchanger, The best heat exchanger has been chosen for Turbo-Compressor. The final improvement Heat Recirculation, Resulted in a 19.1 percent increase in exergy efficiency and reduce NOx emissions rate is 17.93 percent.

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In this research, an ice thermal energy storage (ITES) and a phase change material (PCM) system are coupled to an air-conditioning system as a full cooling load storage system. The system is modeled and examined from exergy, economic and environmental point of views. a multi-objective optimization algorithms, based on genetic algorithm, is applied to achieve the optimal decision parameters which go to the optimal objective functions including exergy efficiency and total cost rate. The optimum point from pareto frontier is found by using TOPSIS decision making method. Finally, the system is compared with the conventional system from electricity consumption, CO2 emission value and payback period aspects. The results indicate that the electricity consumption decrements relative to the conventional system are 4.59% and 7.58% for ITES and PCM system respectively as well as the annual CO2 production of PCM and ITES system is 27.2% and 17.8% lower than the conventional system respectively.

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In this study, a combined cycle power plant with a nominal capacity of 500 MW, including two gas units and one steam unit, was considered by the mathematical model of thermodynamic modeling and the results of the modeling were controlled by the design information of the system. Then, the objective functions are optimized by considering the decision variables. In this multi-objective optimization that has been carried out by Non-Dominated Sorting Genetic Algorithm (NSGA-II), three objective functions of exergy efficiency, CO₂ emission and produced power costs composing of the cost of injected fuel into combustion chamber ,cost of exergy destruction, investment cost and cost of environmental pollutants have been studied. The results indicate that the efficiency of combined cycle power plant depends on design parameters including gas turbine input temperature, compressor pressure ratio, and pinch point temperature and any change occurring in these parameters may lead to noticeable change in objective functions, so that the efficiency of this power plant is increased after optimization up to 8.12 % and heat rate is correspondingly reduced from 7233 (kJ/kWh) to 7023 (kJ/kWh). Similarly, exergy destruction in total system shows 7.23 reduction.

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In the present study, the energy and exergoeconomic analysis for all energy transmission systems from the primary energy source to the energy transfer from the building's envelope for a three-floor building with educational use is presented. The first step is to calculate the energy demand or the heating load required by the Carrier software for all the space. By writing the energy equations, exergy flows of the heating system and total exergy are calculated in different parts of energy dissipation and exergy, as well as the cost of each heating system component. The second stage identifies the undesirable thermodynamic processes of the system based on the determination of exergy losses and calculates the parameter R_ex as the thermodynamic losses rate. The third step is to determine the most feasible reform based on the exergy-economic concepts, so that a parameter called the ECE is calculated as the effectiveness of the exergy cost for all energy transmission systems from the primary energy source to the energy transfer from the building's coatings. Consequently, the most energy dissipation and exergy is related to the production stage and are 188.80, 295.42 kW, respectively. Also, by calculating R_ex and ECE, it is determined that hot water boilers and energy production stage need more to be optimized and improved.