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The principal aim of the current research is the design and optimization of a multi-generation unit capable of generating electricity and potable water and hydrogen. The system comprises a gas turbine unit, a high-temperature solid-oxide fuel cell (SOFC), a combustion chamber, and a multi-effect desalination (MED) system. The pressurized steam and fuel enter the anode side of high-temperature SOFC and the air goes to the cathode side. Due to reactions inside the SOFC, a high amount of electricity produces, and excess H 2 enters the combustion chamber. Hot flue gases can run a gas turbine and a MED unit to generate more electrical power and desalinated water. The study illustrated the impact of current density on voltage losses and output power and output voltage of SOFC. A parametric examination is also conducted to demonstrate the influence of primary design variables on the system performance. Exergo-economic multi-criteria optimization is used to determine the optimized parameters to obtain the higher efficiency and lower cost of fuel and equipment. Calculations represented that the suggested arrangement is able to generate 53.46 kg/s desalinated water, and 54.8 MW electricity and 7.43 kg/h hydrogen energy. The system exergy efficiency under this condition is about 36.45% but the results of optimization showed that this value could rise up between 50.8% and 61.17% with the lowest system cost.

In the current work, a solar-based energy plant that includes an organic Rankine cycle, an NH 3 − LiNO 3 operated refrigeration system, reverse osmosis desalination, and hydrogen production device are integrated, modeled, and optimized. A parametric examination is designed with Matlab software to show the impact of varying primary system variables on outputs like system total energy, exergy efficiency, and total exergy output. All processes have been carried out for different working fluids, namely iso-butane, Propane, n-octane, and the results are compared. Parametric analysis reveals that at solar radiation of 800 W/m2, which is reasonable for the sun in most of the Middle East, selecting n-Octane as a working media results in an increase in the hydrogen production rate of about 150%. This also confirms the importance of selecting the right working fluid for the ORC unit. Moreover, the influence of substantial decision variables on the hydrogen production, net out pout power, exergy efficiency indicated that multi-criteria optimization is necessary. The multi-objective optimization strategy suggests the TIP = 1753 kPa, Toil = 99 °C , η i s t u r = 0.9, η i s p u m p = 0.87, and AHeliostat = 2800 m2, for the optimum state of the studied system. Additionally, the scatter distribution and sensitivity analysis for optimum point introduced by multi-criteria optimization utilized for better understanding the optimization process.

In the present work, the performance improvement of a waste heat recovery system is investigated by applying a fuel cell and thermoelectric generator. With the use of energy, exergy, exergo-economic, and environmental analyses (4E analysis), the performance of the improved system is evaluated. A mathematical simulation in the Engineering Equation Solver (EES) is developed for basic and modified systems. Comparative analysis is carried out to demonstrate the benefit of the suggested system. The logical and correct combination of appropriate subsystems can lead to the maximum exploitation of an energy source, which is the innovation of the present work. The comparison of suggested system (PR/FC-TEG) with the CHP system indicates that the net output power of the PR/FC-TEG system is 3881 kW compared with 958.4 kW for the CHP system. However adding fuel cell to the PR/FC-TEG system increase output power by about 2162 kW, and it imposes 4823 kW exergy destruction rate to the system. The exergy destruction rate of the PEM FC, regenerator, and vapor generator are about 88.96% of the total exergy destruction rate, which infers the importance of these components in the PR/FC-TEG system improvement. Parametric analysis on the PR/FC-TEG performance with changing four influencing parameters is performed. Results indicate that increasing the turbine 1 inlet temperature by about 1.1% increases the cost of generated electricity from 72.92 to 73.88 $/GJ and decreases the sustainability index from 1.68 to 1.65. The multi-objective optimization of the developed system can be a promising option for future study.

In the present work a comparative exergy analysis, multi-objective optimization, as well as extended environmental analysis of a geothermal-based power and refrigeration system, is carried out. Different arrangements with the ammonia-water refrigeration cycle, organic Rankine cycle (ORC), and thermoelectric generator (TEG) are investigated. The current work novelties are the presentation of a novel power-refrigeration system driven by a geothermal source and the employment of TEG units to recover geothermal energy, besides extended environmental assessment. The results of sensitivity analysis indicate that the highest net output work capacity is for the suggested system (configuration 3). Exergy analysis exhibits that in all cases, the absorber has the highest exergy destruction rate and one of the lowest exergy efficiency because it is the first component, which gains the heat from the geothermal source. The suggested system produces 495.2 kW net output power and the highest energy efficiency of 19.42%, which are 131.7 kW, and 3.84% higher than configuration 1(base system). Optimization results represent that in the optimum point, W net shows about 33.3% improvement compared with the un-optimized condition. It is found that configuration 3 which consists of cogeneration with two loops of ammonia-water power cycle with refrigeration system along with an additional thermoelectric generator for enhanced waste heat recovery has the highest environmental footprints because of multiple components installed that would occupy more space, electricity, materials, and other resources for its construction, operation, maintenance, and end-of-life.

Current work deals with exergy and exergoeconomic performance evaluation and bi-objective optimization of a newly introduced advanced energy system with geothermal source. The suggested system is composed of a low-grade organic Rankine cycle, an absorption chiller, and a low-temperature PEM electrolyzer. In three stages, the thermal energy of geo-fluid is transferred to the organic Rankine cycle, the refrigeration cycle, and the PEM electrolyzer. The generated electricity by ORC feeds to the electrolyzer to produce hydrogen as a suitable energy storage. Using a prepared code in MATLAB software, thermodynamic and economic behavior of the system is simulated properly. The exergy analysis outcomes show that the PEM electrolyzer, generator, and heat exchanger are responsible of 77% of total exergy destruction rate of studied system so that electrolyzer with 1218 kW has the highest irreversibility among all components. Calculations show that the overall energy and exergy efficiency of the system are 41 and 50%. In addition, parametric study on different variables such as geothermal source temperature, reference environment temperature, and turbine inlet pressure is considered. To find the optimum states of studied system, various bi-objective scenarios are presented. The results of optimization represent that based on introduced optimization states and employing designer criteria, the best optimum state of suggested system can be determined. A novel aspect of current works goes back to the bi-criteria optimization to determine the optimum states of the suggested system.

The present study deals with the development and thermodynamic assessments of a solar-assisted Kalina cycle with solar energy as the prime mover. Three configurations of the studied systems were su...

The primary goal of the current study is thermodynamic and environmental modeling and multi-objective optimization of a new hybrid energy system. The suggested ocean-based energy conversion system consists of an organic Rankine cycle (ORC), a solar flat plate collector, a proton exchange membrane (PEM) electrolyzer boosted with thermoelectric generator (TEG) module. Exergy and exergo-environmental as two powerful tools are employed to the precise assessment of the suggested system. To achieve the best performance of the integrated system, multi-criteria optimization with different objective functions is carried out. As the results of the parametric analysis indicate, defined objective goals have an appropriate conflict with changing decision variables, which is necessary in multi-criteria optimization. Four decision variables namely solar flat plate collector area ( A p ), solar radiation intensity (I), collector temperature ( T col ), and condenser temperature ( T cond ) are chosen as decision variables. In all optimization scenarios, the net output power is common, which is based on the selected optimum points value changing between 201.02 kW and 268.17 kW. Additionally, in various optimization scenarios, the area of solar flat plate collectors tends to get a higher value in the allowable domain. The provided information in multi-objective optimization can provide good insight to engineers and system designers to select the best system configuration.

The current work is about analysis and multi-objective optimization (MOO) of weir-type solar still systems equipped with phase change material (PCM) regarding the exergetic and economic performance. To do so, the energetic and exergetic modeling of the suggested system is conducted then the substantial economic factors is applied to obtain the total cost rate of the considered SSDS. The total exergetic efficiency and total annual cost (TAC) is considered objective functions. Four parameters include mass of the PCM (mPCM), inlet brine water flow rate ( $$ {\dot{m}}_{\mathrm{f}} $$ ), gap distance (d), and insulation width (xins) is chosen as decision variables. Moreover, a genetic algorithm–based MOO was applied to find the optimum states of evaluated solar still unit. The outputs represented that increasing the brine feed water mass flow rate does not affect the TAC while decreasing distilled water production rate. The scattered distribution of optimum states infers that the optimum value of PCM mass is about 1 kg. In addition, applied MOO reveals that with optimization of the studied system, the exergy efficiency increases about 1.47% and the annual distilled water increases 4.35% compared with the non-optimized system. The suggested system is capable to produce fresh water in remote areas without any pollution as well as in a low cost rate.

The objective of current research is the optimization of a novel parabolic trough solar collector assisted power-refrigeration system. The innovative system utilizes CO2 as a working fluid, which is a natural medium and consisted of three sub-cycles: a Brayton cycle, a Rankine cycle, and a vapor compression refrigeration cycle. The main advantages of utilizing CO2 as working fluid are; available in large quantities, environmentally friendly properties such as negligible global warming potential and zero-ozone depletion, and excellent thermodynamic properties. The required heat energy demand of the system is supplied by solar energy using a PTSC. The thermodynamic performance of the system is examined in terms of energy and exergy analyses for a specified design configuration. An economic analysis of the suggested system is carried out for the optimization procedure. With the optimization results, the optimum design parameters are determined for better system operating conditions. The results of tri-objective optimization represent that the total exergy destruction rate decreased 436.7 kW regarding the basic system with the initial value of design parameters. However, the net power output of the system decreased from 353.21 kW to 280.1 kW, and the total annual cost of the system decreased from 8.215 $/h to 5.74 $/h.

The present work aim is performance improvement of an integrated geothermal system by proposing the integration of organic Rankine flash cycle (ORFC) with the Proton exchange membrane fuel cell (PEMFC) and waste heat recovery from condensers using thermoelectric generator (TEG) modules. To achieve this goal, a novel integrated system is proposed, thermodynamically modeled, investigated, and compared with the conventional system. To assess the performance of proposed system, thermodynamic and economic evaluations are performed. The results indicate that R123 as working fluid, has the best performance for the conventional and proposed systems. The findings demonstrate that with employing TEG modules an increase of 2.7% and 2.8%, for the first and second law efficiencies can be obtained respectively. Additionally, the results of parametric analysis indicate that however the geothermal fluid temperature increment decreases the first and second law efficiencies of the system, it leads to the net output power enhancement. Also, enhancement of the flash vessel pressure ratio increases the first and second law efficiency as well. Additionally, the simple payback method showed that a payback time between 1.25 years and 25 years according to the TEG modules cost can be achieved.

The current research deals with thermodynamic and economic analyses and optimization of a geothermal system integrated with organic Rankine flash cycle (ORFC) and a polymer electrolyte membrane fuel cell (PEM-FC). A thermodynamic model for ORFC and PEM-FC is developed to investigate employing the PEM-FC in a combined geothermal ORFC. A comparative study is carried out to determine the effect of applying PEM-FC in a geothermal based ORFC. The validation of PEM-FC simulation with experimental data from the literature shows a good agreement. The results of numerical modeling indicate that using the rejected heat in the PEM-FC instead of the low-temperature geothermal source can increase the net output power from 254.9 kW to 1628.9 kW and the exergy efficiency from 23.77% to 36.19%, in the case of R123 as working fluid for the ORC system. Furthermore, using the PEM-FC imposes 9.07 US$/h cost rate to the system. Additionally the parametric study shows that the net output power and the total cost rate of the system are two major objective functions for the optimization. Thus, a multi-objective genetic algorithm is applied to determine the optimal values of design parameters with respect to some practical constraints. The results of the multi-criteria optimization represent that the optimum value of decision variables with considered objective functions are T 1 = 116 °C , r f l a s h = 0.55 , P F C = 230 kPa , and P 4 = 1208.4 kPa .

Thermoelectric waste heat recovery systems (WHRSs) can be used appropriately to recover wasted heat from various industrial processes. In the current work, new thermodynamic modeling was developed to harvesting waste heat from an integrated system includes an externally fired gas turbine and a biomass gasifier by three thermoelectric WHRSs. The biomass system consisted a gas turbine cycle, an organic Rankine cycle (ORC) and a domestic water heater were first thermodynamically modeled, and then effects of adding thermoelectric WHRSs to different locations of the system were investigated. It is observed that first law efficiency of the system ( η 1 ) will become 17.11% (an increase of 0.35%) if the total output heat from the stack enters W H R S s . The efficiencies of the system can be increased from 16.76% to 17.93% by placing a WHRS on the condenser of ORC. Moreover, the operating parameters have a significant effect on the integrated system efficiency; the influence of increasing α G E on the efficiencies is in contrast to the effect of enhancing α c o n d . In addition, an economic assessment of integrating WHRSs with the biomass gasifier integrated system is conducted and the conditions are indicated under which the proposed system is profitable. Furthermore, the results of genetic algorithm based multi-objective optimization shows that with the use of γ DU = 2 and γ L , O R C = 30 defined thermal efficiencies are at their optimum state.

The current research deals with the thermodynamic and economic assessments of an integrated thermoelectric generator system with the liquefied natural gas production process. The main aim of the present work is investigation the influence of the thermoelectric generators modules location, in a liquefied natural gas production cycle, on the thermodynamic and economic criteria. A Matlab code has been developed to assess the integrated system performance. Suggested integrated systems include adding the thermoelectric generators between the condensers and evaporators (Case I) and adding the thermoelectric generators between the condensers and ambient air (Case II). The results show that the position of the thermoelectric generators considerably influences the system performance. The results indicates that in Case I (with adding thermoelectric generators between condenser and evaporator) the system performance deteriorate drastically. The results for Case II exhibit that the coefficient of performance increases with an increase in x value. Moreover, economic analysis of employment of thermoelectric generators in liquefaction cycle indicates that with thermoelectric generator cost of 1 $/W the payback rate of investment is less than 2 years (1.29 years).

In this paper, a numerical study is conducted to examine the energy and exergy performance and multi-objective optimization of a novel exhaust air heat recovery system made up of a building integrated photovoltaic/thermal (BIPV/T) collector and a thermal wheel (TW) system. The innovative BIPV/T-TW system is capable of pre-heating/pre-cooling the ambient fresh air in winter/summer and also producing electricity. Comparisons are carried out on the basis of energy and exergy by considering three different exhaust air heat recovery systems including the BIPV/T-TW system, the conventional BIPV/T collector, and the convectional TW system. It is observed that the BIPV/T-TW system has the best energy performance among the considered systems in all months of the year, while its exergy performance is lower than the BIPV/T system. Then, the multi-objective optimization technique is utilized to obtain the optimal values of geometric and operating parameters in order to maximize the annual useful energy and exergy obtained from the BIPV/T-TW system. It is found that annual useful energy and exergy gained by the optimized system is 196.31 MWh and 30.15 MWh, which is 563.8% and 1394.1% higher than the un-optimized system, respectively.

This paper mainly focuses on the design and optimization of a novel integrated system to meet fresh water, electricity, and hot water demands. A novel combination of different system is used to generate multi products. The exergy and economic analyses are combined to carry out a parametric study to find the impact of main decision variables on a polygeneration system. The exergy analysis reveals that combustion chamber and gasifier have the highest exergy destruction rates with 84% of the system total exergy destruction rate. In addition, the system exergy efficiency shows that in the initial state, the exergy efficiency of polygeneration system is 27.9%. Results show that an increment in the gasification temperature from 950 K to 1150 K leads to fresh water flow rate increases from 1060 m3/day to 1160 m3/day. The parametric study of the system reveals that the defined objective functions are highly depends on the changes in the nine decision variables. Using a genetic algorithm optimization method, the optimum design values are obtained. The results of multi-objective optimization show that within reasonable changes for decision variables, the system exergy efficiency can change between 20% and to 42%, and the system total cost rate can vary from 100 $ / h to 600 $ / h .

In the current research, an innovative biomass-based energy system is proposed for power and desalinated water production. The plant's primary components consist of a gasifier, a compressor, a heat exchanger, a gas turbine, a combustion chamber, and a Multi-effect desalination with thermal vapor compression (MED-TVC) unit. A comprehensive thermodynamic and thermoeconomic assessment is conducted on the proposed system. Besides, a parametric study is conducted to determine the effect of primary decision variables on the system performance. Multiple objective optimization using the multi-objective grey wolf optimizer (MOGWO) algorithm is applied to obtain the optimal solution with the highest exergy efficiency and the minimum amount of total cost rate. The artificial neural network (ANN) has an intermediary role in the optimization process to decrease computational time and enhance optimization speed. The relation between the objective function and decision variables is investigated, employing ANN to determine the energy system's optimum point. The generation rate for power and freshwater at the optimal point is equal to 5127 kW and 38.6 kg/s, respectively. Besides, the optimum value of the exergy efficiency and total cost rate are computed as 15.61% and 206.78 $/h, respectively. The results also revealed that the number of effects of the desalination unit does not affect the carbon dioxide emissions. Moreover, the scatter distribution of the key decision variable indicates that the air compressor pressure ratio is not a sensible variable, and their optimum points are distributed across the entire domain.

The present research deals with a novel hybrid system comprises of a salinity gradient solar pond (SGSP) integrated with a proton exchange membrane fuel cell (PEMFC) and a thermoelectric generator (TEG). The key novelty of this research is the use of PEMFC waste heat to increase the performance of the low-temperature heat source (solar pond). Also, a thermoelectric generator is employed in the proposed setup for complete waste energy recovery. In this paper, the proposed system's energy, exergy, and economic (3E) performance are investigated, as well as compared with two additional systems that were modelled by excluding TEG and PEMFC to showcase the benefits of the sub-systems in the final configuration. A parametric study is also conducted to investigate the effect of significant parameters on the overall system performance. The simulation results indicated that the integrated system's net output power is 2288.8 kW at a base case operating condition, with energy and exergy efficiency of 11.26% and 13.17%, respectively, and a system cost rate of 394 $/h. In comparison to other components in the integrated system, SGSP alone accounts for 75% of total exergy degradation and has the highest investment cost of 66.70 $/h. Further, to achieve the best system performance, a multi-criteria optimization is performed for the suggested system with net output power, energy efficiency, exergy efficiency, and system cost rate as objective functions. Besides, the multi-criteria decision analysis (MCDA) is also carried out on the obtained Pareto front using TOPSIS decision-maker to select the best operating condition that improves the output power, energy, and exergy efficiency by 52.6%, 49.6%, and 61.8%, respectively, at the expense of 5.2% increase in the system cost rate. The current investigation demonstrates how an appropriate optimized design of an integrated energy system using SGSP, PEMFC, and TEG can improve the overall performance with reasonable cost increment.

In this study, thermoeconomic optimization is applied to a modified transcritical ( CO 2 ) refrigeration cycle. Modified cycle includes an extraction of saturated vapor as a coolant stream from the separator feed to the intercooler. In order to perform multi criteria optimization two objective functions consist of cooling capacity and annual cost rate are chosen. Gas cooler temperature ( T gc ) , gas cooler pressure ( P gc ) , extraction mass flow rate ( α ) and evaporator temperature ( T ev ) are selected as decision variables based on parametric study. The thermodynamic and economic modeling of the system is performed. To determine analytical, objective functions GMDH (group method of data handling) neural network method is used and finally with a developed code in Matlab optimal values of decision variables have been obtained. In addition, to better understanding the change of decision variables in optimum point, the scatter distribution of these variables is carried out.

The objective of the present work is to investigate the improvement in the energetic and the exergetic performances of glazed and unglazed building integrated photovoltaic/thermal (BIPV/T) systems with the help of multi-objective optimization based on Genetic Algorithm (GA) for Kermanshah, Iran climatic condition. In the proposed BIPV/T system, the cooling potential of ventilation and exhaust airs is used for cooling the photovoltaic (PV) panels and also heating the ventilation air by heat rejection of PV panels. The performance evaluation criteria comprise the first and second law efficiencies. Initially, a multi-objective optimization approach is used to find the optimum values of the geometric parameters and air mass flow rate which maximize the annual average first and second law efficiencies. In the second step, the performances of the optimized and un-optimized BIPV/T systems are evaluated and compared for a representative day in the month of January, as well as for a complete year. The obtained results revealed that the optimized glazed system has higher values of annual average first and second law efficiencies (39.27% and 10.75%, respectively) than the un-optimized system (33.68% and 10.51%, respectively). Moreover, it was found that the annual first law efficiency of the optimized unglazed system is 5.49% higher than that of the un-optimized system but that the annual second law efficiency of the optimized unglazed system is 0.23% lower than the un-optimized system.

In this paper, a new design of a solar tower system boosted with a thermoelectric generator (TEG) for power generation and distilled water production, is proposed and investigated. The suggested system includes a solar tower unit with atmospheric air as heat transfer fluid, a helium Brayton cycle, two organic Rankin cycles (ORCs) with R-123 as working fluid, thermoelectric generator, and reverse osmosis (RO) desalination unit. The systems under investigation are the gas turbine-helium Brayton system (GT-HBS) as the primary system and the gas turbine-helium Brayton system integrated with TEG and RO (GT-HBS/TEG-RO) as the proposed system. A new aspect of the present work is the waste heat recovery using TEG modules to enhance the performance. Analysis indicates that the energy efficiency of GT-HBS and GT-HBS/TEG-RO systems is 43.88% and 62.44% and the exergy efficiency of GT-HBS/TEG-RO is 20.23 % higher than the GT-HBS. Additionally, the results show that employing TEGs in the primary system leads to the net output power, energy, and exergy efficiencies increment about 941 kW, 3.7%, and 5.28%, respectively. Based on the parametric analysis with an increasing inlet temperature of the gas turbine, the net output power, energy, and exergy efficiencies, and volume flow rate of the freshwater increase. Furthermore, the increment of the direct normal irradiation leads to the energy and exergy efficiencies enhancement. Besides, raising compressor pressure ratio, the net output power, energy, and exergy efficiencies first increase intensively then decrease gradually. The analysis of the new proposed system can be helpful to the system designers to create new system arrangements with higher performance.

The current study deals with thermodynamic modeling and multi-objective optimization of a new multi-generation energy system using geothermal as the primary energy source. The proposed system includes a Kalina cycle, a refrigeration unit, thermoelectric module, steam turbine, and heating unit. The new aspects of the proposed system are using the thermoelectric system to low temperature heat recovery and using the benefit of the multi-product. The system exergy analysis shows that the reverse osmosis desalination unit with 449.1 kW has the highest exergy destruction rate in the system. Additionally, three components i.e., reverse osmosis unit, heating system, and steam turbine are responsible for 82.8% of exergy destruction of the system. Exergo-economic analysis revealed that the turbine and the thermoelectric module have the highest cost rates of 12.51 US$/h and 3.62 US$/h respectively. It also concludes that the sum of the cost rate of component and associated exergy destruction cost rate, a significant exergo-economic parameter, for the turbine and reverse osmosis unit are the highest values. Parametric analysis of the proposed system for geothermal source pressure, steam turbine backpressure, Kalina turbine backpressure, and ammonia mass fraction of basic solutions are carried out. The unit cost of product and exergy efficiency are objective functions for optimization. Multi-criteria optimization indicates that using the Linear Programming Technique for Multidimensional Analysis of Preference (LINMAP) method based on suggested design variables, can reduce the unit cost of the product to 0.107 US$/kWh, and the exergy efficiency can be increased up to 15.86%.

The goal of this article is to propose and analyze a novel solar driven multigenerational system producing electricity, cooling, hydrogen and fresh water. The system consists of parabolic dish collector with hybrid nanofluids, re-compression sCO2 Brayton cycle, proton exchange membrane (PEM) electrolyzer, desalination unit and double effect lithium-bromide/water absorption cycle. To achieve high system performance and to meet the energy demand in the absence of solar flux, a thermal energy storage system has been used having high temperature phase change material (PCM). This system is able to continue system operation after the sunset and also ensure the stable fluid temperature at the turbine inlet. The performance of the proposed system is assessed by varying the different input parameters such as; inlet temperature, mass flow rate, direct normal irradiation (DNI), wind speed and turbine inlet temperature (TIT). In addition to the energy and exergy analysis, exergoeconomic approach is used to calculate the cost rate and exergo-economic factor of all the components of the integrated system. The results indicate that the overall energy and exergy efficiencies of the proposed system are 31.59% and 30.02%, respectively; while production of fresh water and cooling load are 1.564 kg/s and 196.1 kW, respectively. The exergoeconomic results show that Levelised cost of electricity and total cost rate of exergy destruction are 0.1387 $/kWh and 530 $/hr., respectively with payback period of 9.5 years. Moreover, single- and multi-objective optimizations are carried out to determine the optimal design using a genetic algorithm method in EES (engineering equation solver). Total cost rate and overall exergy efficiency are the two desired objectives to be optimized.

One of the most appropriate approaches for enhancing the performance of the energy systems is integrating different subsystems for producing various beneficial products simultaneously. In the present study, a poly-generation system including a Kalina cycle, a reverse osmosis unit, a PEM electrolyzer, and a thermoelectric module that can generate power, fresh water, hot water, and hydrogen is examined. A thermodynamic simulation code in Engineering Equation Solver (EES) is prepared to predict the behavior of system. Using the exergy analysis different location of system with high irreversibility is determined. As the results show in the base case, the geothermal cycle condenser with 89.29 kW, reverse osmosis (RO) unit with 68.97 kW, heat exchanger 2 with 37.68 kW, and steam turbine with 22.52 kW have the highest exergy destruction rate respectively. The parametric analysis for identifying the influence of five decision variables namely steam turbine inlet pressure (P2), steam turbine back pressure (P4), vapor generator outlet pressure (P10), Kalina turbine backpressure (P13), and temperature difference of the heat exchanger (TD) is conducted. Additionally four major outputs consisting of exergy destruction rate (kW), exergy destruction cost rate ($/h), and electricity cost rate ($/h) are determined for implementing multi-criteria optimization. A tri-objective optimization to find the optimum states of the suggested system is conducted. With employing a selection method, the system arrangement with 328.2 kW of exergy destruction rate, 18.4 $/h of exergy destruction cost rate, and 12.83 $/h of electricity cost rate with determined value of decision variables is selected as final optimum state.

Intermittent behavior of renewable energy triggered researchers for using energy storage systems to provide continues operation of renewable-based energy systems. In the current study, an integrated energy system including compressed air energy storage, Rankine cycle, Proton Exchange Membrane (PEM) fuel cell (FC), and thermoelectric generator (TEG) modules are investigated to introduce a new system. To show effects of adding TEG units and PEM fuel cell in the new configuration, three arrangements including conventional compressed air energy storage system (CAES), CAES/TEG and CAES/TEG-FC are investigated. It is found that the proposed CAES/TEG-FC system energy efficiency is 31.85%, which is 1.6% higher than conventional CAES. The exergy efficiency of CAES/TEG-FC is 35.13%, which is 1.44% higher than the conventional one. The proposed system generates 35.6 kW hot water and charge/discharge time are 2.91 hr/4.64 hr. A parametric analysis conducted on the discharge mass flow rate, intercooler outlet temperature, compression pressure ratio, and wind velocity with charging time, exergy efficiency, and total useful products as three major outputs. The tri-objective optimization shows by the technique for order of preference by similarity to ideal solution the optimized value of exergy efficiency, total useful output, and charge time are 34%, 1078.46 kW, and 5.28 hr.

A multi-generation system including an absorption chiller, an organic flash cycle, a concentrated photovoltaic module, a reverse osmosis unit, and thermoelectric modules are integrated to produce cooling, heating, electrical power, and freshwater. The important parameters including energy efficiency, exergy efficiency, exergy destruction rate, net output power, and electrical cost rate are identified. The behavior of main outputs are examined with varying decision variables namely geothermal temperature, flash vessel inlet pressure, and pump Ι outlet pressure. Thermal modeling of the proposed system indicates that the energy efficiency, exergy efficiency, and net output power are 5.46%, 20.16%, and 70.85 kW higher than the conventional system. Moreover, exergo-economic outputs demonstrate that the thermoelectric generator module with 11.34 $/h and heat exchanger 2 with 8.98 $/h have the maximum exergy destruction cost rate. Finally, according to different multi-objective optimization scenarios it is found that through the first scenario, the electricity cost rate shows the minimum value of 108.4 $/h.

Current study represents the thermodynamic modeling and exergy analysis of a compressed air energy storage system boosted with thermoelectric generator (CAES/TEG). To evaluate the studied system, a comparative analysis between compressed air energy storage system (CAES) with CAES/TEG has been done. Exergy, a powerful tool for analyzing energy conversion systems, is employed to determine the exergy destruction rate and exergy efficiency of the system as well as different related components. The results of exergy analysis indicates that the wind turbine with 35.28 kW (44.81% of total exergy destruction rate) has the highest exergy destruction rate and after that in the second and third places are combustion chamber and cavern. Findings indicate that with adding thermoelectric modules to the CAES system, the output power of Rankine cycle and organic Rankine cycle increase about 1.16 kW and 0.959 kW in comparison with CAES system, which these changes lead to increasing the net output power of the system in CAES/TEG system from 33.59 kW to 35.71 kW compare with CAES. Moreover, the influences of main parameters such as compressor mass flow rate, compressor pressure ratio, and combustion chamber outlet temperature and wind speed on the CAES/TEG performance are investigated.

In this study, two-objective optimization of a solar-driven carbon dioxide (CO2) based transcritical Rankine cycle for power and heat generation is carried out. With Engineering Equation Solver (EES), the monthly thermodynamic performance of the integrated system is determined. Results show that the exergy rate of recovered heat in the winter is 0.029 kW, which is relatively low due to low solar intensity for the winter season (512 W/m2). The results revealed that the highest overall energy efficiency of the system takes place in July, and the highest overall exergy efficiency is calculated for August. The results of the parametric study indicate that changing the considered decision parameters has different effects on the recovered heat and net output power of the integrated system. Hence, a two-objective optimization with net output power and recovered heat as optimization targets is performed. In order to achieve the optimization solutions, the objective functions are defined seasonally. The results of optimum states regarding the concept of ideal point show that the best performance of the system is in summer with 0.262 kW for net power output and 0.921 kW for recovered heat.

In the current work thermodynamic modeling, exergo-economic and multi-objective optimization of an integrated geothermal based CCHP system coupled with thermoelectric generator is examined. A numerical simulation in the Engineering Equation Solver (EES) is developed to simulate the behavior of the CCHP/TEG integrated system. Exergo-economic modeling to find the cost formation of different streams is done and parametric study with considering different thermodynamic and economic criteria is performed. Thermodynamic analysis reveal that the net output power and total useful products are 139.7 kW and 807 kW. Moreover, the energy and exergy efficiency of the considered system is 55.81 % and 22.63 %, respectively. Parametric study on the CCHP/TEG system for net output power, exergy efficiency, electrical cost rate, and total useful products is carried out. Regarding parametric study the multi-objective optimization with exergy efficiency and electrical cost rate is done. The concept of ideal point is employed to determine the final optimum conditions of CCHP/TEG system. The optimization calculations show that in the final optimum values of the electrical cost rate and exergy efficiency of the system are 12.52 $/h and 22.11 %, respectively. In addition the optimization process indicates that the optimum turbine inlet pressure and separation I inlet temperature are around 8 bars and 13 bars.

The development of heat and power generation systems has a major step towards sustainable development, reducing fossil energy consumption and reducing environmental pollution. Integrated energy systems are considered widely due to their high efficiency. In the present paper, an intercooled gas turbine system is developed to achieve a system with high thermal efficiency as well as better economic performance and cleaner production. The main goals of the suggested system is improvement of thermodynamic and exergo-economic performance beside multi-criteria optimization, which lead to improve the system sustainability. The intercooled gas turbine in the current work integrated with hot water system and thermoelectric generator unit to develop an advanced combined heat and power system. A comprehensive energy, exergy, and exergo-economic analyses are employed to price assessment of the new introduced system. A comparative analysis with conventional intercooled gas turbine system is presented. The results of thermodynamic modeling indicate that an improvement about 613.3 kW, 8.21 kW, and 12.3 kW can be obtained in the gas turbine, Kalina cycle, and regenerative organic Rankine cycle subsystems. The results of energy and exergy analysis show that the values of both energy and exergy efficiencies for all subsystems experience increment in the new introduced. Parametric analysis based on thermodynamic and exergo-economic criteria is done and a triple objective optimization conducted to determine the best system configurations. The Technique for Order of Preference by Similarity to Ideal Solution is employed to choose the final optimal state of the system. The result of optimum selection among non-dominant solutions suggested by Pareto points indicates that the energy efficiency, total exergy destruction rate and electricity cost rate are 53.91%, 2392.01 kW, and 52.29 $/h.

A comprehensive thermodynamic study of a solar integrated energy system consisted of a solar flat plate collector, an organic Rankine cycle, a thermoelectric generator, and a proton exchange membrane electrolyser is undertaken to generate power and hydrogen. The Matlab and Engineering Equation Solver software are linked, and various optimisation scenarios are investigated. The results of computational analysis indicate that with adding a thermoelectric generator unit in the system about 14 kW of energy in the form of electricity can be obtained from the waste heat of condenser. Various optimisation schemes with exergy efficiency, exergy destruction rate, as well as hourly hydrogen generation as optimisation targets are considered. The optimisation results comparison between base case and optimum design shows that exergetic efficiency improves by about 2.3% and rate of exergy destruction decrease by about 0.791 MW.

The use of biomass due to the reduction in greenhouse gas emissions and environmental impacts has attracted many researchers’ attention in the recent years. Access to an energy conversion system which is able to have the optimum performance for applying valuable low heating value fuels has been considered by many practitioners and scholars. This paper focuses on the accurate modeling of biomass gasification process and the optimal design of a multigeneration system (heating, cooling, electrical power, and hydrogen as energy carrier) to take the advantage of this clean energy. In the process of gasification modeling, a thermodynamic equilibrium model based on Gibbs energy minimization is used. Also, in the present study, a detailed parametric analysis of multigeneration system for undersigning the behavior of objective functions with changing design parameters and obtaining the optimal design parameters of the system is done as well. The results show that with exergy efficiency as an objective function this parameter can increase from 19.6% in base case to 21.89% in the optimized case. Also, for the total cost rate of system as an objective function it can decrease from 154.4 $/h to 145.1 $/h.

This study deals with thermodynamic and economic analysis of a combined gas turbine and Organic Rankine Cycle integrated with a biomass gasifier. A modified model is used to increase the precision of the gasifier thermodynamic model. Seven decision variables, namely, biomass gasification temperature (Tgasif), combustion temperature (Tcomb), gas turbine inlet temperature (T3), gas turbine isentropic efficiency (ηGT), compressor isentropic efficiency (ηcomp), compressor pressure ration (rp) and maximum ORC operating pressure (P3R), are selected as the main decision variables of the combined system. The total cost rate and exergy efficiency of the system are chosen as the two main objective functions. A group method of data handling (GMDH) type neural network and evolutionary algorithm (EAs) are used for modeling the effects of the seven decision variables on both objective functions. The result of multi-objective optimization shows that the exergy efficiency of the system is 15.6%, which can be increase to 17.9% in the optimal state, regardless of the total cost rate of system as objective function. In addition, in order to better illustrate the effects of decision variables change in three selected points of the Pareto curve, a sensitive analysis is performed.

In this research study, a 40 MW gas turbine power plant, which is coupled with a multi-effect desalination system with thermal vapor compression, is investigated. The energy, exergy and exergoeconomic analyses of the integrated plant are presented. As the number of effects in a desalination system is a key parameter, the effect of number of effects on the system performance is investigated. The genetic algorithm-based multi-objective optimization is applied to determine the best decision variables. To achieve the best optimization states, different scenarios of multi objective optimization based on the total exergy destruction rate, unit electricity price, total cost rate, gain output ratio, distilled water cost, and total exergy efficiency are examined. Additionally, seven decision variables are compressor pressure ratio ( r p ), combustion temperature ( T 3 ), compressor isentropic efficiency ( η c ), gas turbine isentropic efficiency ( η GT ), top brain temperature (TBT), last effect temperature (LET), and ejector compression ratio (Cr). The parametric analysis results indicated that although increasing the number of effect enhance the distilled water production rate, it increases the total cost rate of the system. With motive steam flow rate of 14 kg/s, results showed that distilled water production rate is 12294 m 3 / d a y . Additionally, with three different scenarios the optimal states of integrated system are introduced. The results of optimization scenarios suggested different optimal states that are best guide for designer to select the best system configuration.

The present study deals with energy, exergy and environmental evaluation of an integrated ocean thermal energy conversion (OTEC) system include a flat plate solar collector, an organic Rankine cycle, an electrolyzer system boosted with a thermoelectric generator (TEG) unit. To precise assessment of suggested systems and determine the effects of adding thermoelectric generator to the system a comparative analysis is carried out. Two considered systems are solar ocean thermal energy conversion (S-OTEC) and solar ocean thermal energy conversion with thermoelectric (S-OTEC/TEG). A thermodynamic model is formed using Engineering Equation Solver (EES) to solve the set of linear equations governing on the component of the system. The result of exergy analyses shows that adding thermoelectric module to the S-OTEC results in exergy efficiency increment by 6.27%. Also adding thermoelectric unit to the system increase gross output power by 12.64 kW that the TEG pump input work in this case is 4.96 kW. Although the exergy destruction rate of the S-OTEC/TEG has a higher exergy destruction rate than S-OTEC, the exergy efficiency of S-OTEC/TEG is higher than S-OTEC. Environmental impact assessment criteria namely sustainability index (SI) and modified sustainability index (SI2), represent that applying TEG module to the system improves the SI2 while decreases the SI. Based on obtained results with methanol as working fluid, the SI change from 0.106 for S-OTEC to 0.183 for and S-OTEC/TEG system. In addition, the SI2 change from 1.949 to 2.220 when the TEG module added to the integrated system.

The present study deals with exergy and exergo-economic evaluation of a 1 MW combined cooling, heat and power (CCHP) system, composed of a natural gas prime mover internal combustion engine located in the main campus of the University of Kashan, Kashan, Iran. Using appropriate linking between engineering equation solver (EES) and MATLAB software, thermal and economic modelling and multi-criteria optimisation (MCO) have been performed. The optimisation results showed that the minimum total exergy destruction rate occurs for the exhaust gas extraction factor of 0.68, which causes $33.52/h total cost rate. For this case, among all of the system components the highest exergy destruction rate of 1,700 kW belongs to the engine. In addition, the results of the genetic algorithm-based multi-objective optimisation represented that the optimisation causes $2.68/h decrease in total cost rate and reduction of 4,512 kW in exergy destruction rate.

A novel integrated power generation and refrigeration system proposed in this paper. The system consists of parabolic trough collectors, supercritical-CO2 based Brayton cycle, an absorption refrigeration cycle, and a thermoelectric generator. Of particular interests of this paper are thermoelectric power generator and performance characteristic of closed Brayton cycle working with CO2. Employing energy and exergy analyses, the effect of integrating thermoelectric module at different points is studied by comparing power generation and efficiency before and after applying the thermoelectric module. Besides, the whole system is analyzed with the use of first and second law thermodynamics to determine energy and exergy efficiencies with exergy destruction rates. Furthermore, a multi-objective optimization method is conducted by defining two scenarios using different types of objective functions to specify the optimum conditions of the system with the thermoelectric module. According to the results, the energy and exergy efficiencies of the system are increased by 1% with the presence of the thermoelectric module. In addition, employing thermoelectric lead to the generation of 4.81 kW power from waste energy in different locations of systems.

One of the most substantial aspects of the solar still systems that should be significantly considered is their economic and environment aspects. The present study deals with analyzing and identifying the behaviors of a cascade solar still desalination system in the presence of different insulation types and phase change materials. A Matlab code is developed to solve the energy equations for different components of the system simultaneously using ODE-45 solver. A comprehensive thermal, economic and environment analyses performed on the solar still desalination system with different insulation types and phase change materials. With selecting three objective functions namely total annual cost ( T A C ), exergy efficiency ( η e x ), and exergy-based CO2 mitigation ( φ C O 2 , e x − b a s e d ) , the tri-objective optimization is carried out for two considered cases of solar still desalination units. The thermal analysis represents that among different insulation types phenolic foam with 9.42 k g / m 2 per day has the highest value of distilled water production. The total annual cost analysis infers that the system with paraffin as phase change material (PCM) and glass wool as insulation, with 71.67 $, has the lowest TAC. The tri-objective optimization results demonstrate that for both considered cases three objectives are improved considerably compare with non-optimized solar still systems.

In recent years, reducing the cost of energy production and transmitting electricity in remote areas of the distribution network have attracted many researchers’ attention. One of the methods to fulfill these objectives is using a gas micro-turbine cycle. In this paper, a two-stage micro-turbine with an intercooler was used to produce electricity and heat simultaneously. In this system, the impacts of the effective input parameters, such as compressor pressure ratio, bypass ratio, and re-cooperator yield on cycle performance were studied given that the values obtained from cycle modeling were not continuous, and using GMDH-type neural system (as one of the most widely used neural networks with high potential to model complex data), the desired objective functions were estimated and then simultaneous optimization of the objective functions were implemented. It was shown that the maximum electrical exergy efficiency is 58 % and maximum thermal exergy efficiency is 18 %.

The application of the exergy and exergoeconomic analysis for energy conversion systems is growing steadily. This analysis is particularly useful for energy conversion systems such as the combined-cycle power plant (CCPP). This paper deals with exergy and exergoeconomic analysis of a combined-cycle power plant with supplementary firing. A process simulation program, IPSE Pro, is used to model the combined-cycle power plant. Exergy and exergoeconomic analysis is carried out by developing a Matlab code. Three configurations of the combined-cycle power plant are investigated and the effect of the configurations of a heat recovery steam generator (HRSG) and performance parameters such as fuel mass flow rate of duct burner and pressure ratio of compressor on combined-cycle performance have been studied. Exergy and exergy cost destruction rates are also calculated. Finally, the cost of generated power for the three configurations of combined-cycle power plant is calculated and the best location for the ...

This chapter deals with thermodynamic modeling, parametric analysis, and optimization of an integrated system to recover energy from pressure reduction station in city gate station (CGS). This chapter aims to fully cover the thermodynamic modeling of an integrated system consisting of a turbo expander, an organic Rankine cycle (ORC) and a proton exchange membrane (PEM) electrolyzer to produce and store hydrogen. The pressure of natural gas in transmission pipeline in Iran gas system is high which sometimes go beyond 7 MPa. This pressure needs to be reduced near the cities pipeline pressure to 1.7 MPa. This pressure reduction results in ample potential to recover energy to generate electricity. In the proposed integrated system in this chapter, a comprehensive parametric analysis including the effect of main parameters such as natural gas preheat temperature, the natural gas pressure inlet to turbo expander, the heater mass fuel flow rate, and high temperature of ORC on the system performance is investigated.