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• A novel direct-fired supercritical CO 2 power cycle (DETRC) is proposed. • DME is DETRC's fuel with a high hydrocarbon ratio and self-oxygenating properties. • Cycle performance analysis takes into account the effects of combustion. • Thermal efficiency increases by 25.45 % and unit product cost decreases by 18.31 %. • 554.1 kW DETRC's net power and 9.29 ¢/kW∙h unit product cost available. A direct-fired supercritical CO 2 power cycle with a novel layout and dimethyl ether (DME) as fuel is proposed, named the dual expansion and triple recuperation cycle (DETRC). To obtain accurate cycle simulation results, the combustion products' state parameters and species concentrations are used as the inputs of cycle simulation, which are obtained from a three-dimensional combustion simulation. The performance of DETRC is compared with those of the direct-fired Allam cycle and other published direct-fired cycles. The effects of the CO 2 recycling ratio, excess oxygen coefficient, in-combustor pressure, and turbine outlet pressure on the thermodynamic and exergoeconomic performance are investigated to obtain the optimal operating variables for DETRC. The results indicate that DETRC has excellent thermodynamic and exergoeconomic performance. Compared to the Allam cycle, the exergy losses of recuperators and coolers are reduced significantly, thermal efficiency is increased by 25.45 %, and the unit product cost is reduced by 18.31 % in the DETRC. Compared to the direct-fired cycles in the literature, the thermal and exergy efficiencies increase, and oxygen consumption reduces. The effect of the CO 2 recycling ratio or excess oxygen coefficient on DETRC is non-monotonic. As the CO 2 recycling ratio or excess oxygen coefficient increases, the thermal and exergy efficiencies increase and then decrease, and the unit product cost decreases and then increases. With in-combustor pressure increasing, the thermal and exergy efficiencies increase, unit product cost decreases, and the cycle performance is improved. As turbine outlet pressure increases, the thermal efficiency increases and then decreases, exergy efficiency increases, and unit product cost decreases and then increases. The optimal operating variables are that the CO 2 recycling ratio is 0.95, the excess oxygen coefficient is 1.20, the in-combustor pressure is less than 30 MPa, and the turbine outlet pressure is 5.5 MPa. [ABSTRACT FROM AUTHOR]

• BOG cold exergy and PTORC are employed to recover waste heat of a PEM fuel cell. • The PEM fuel cell is simulated mathematically and results are validated. • Thermodynamic and exergoeconomic analyses are performed for the system. • A parametric study is considered to illustrate effects of important parameters. • Proposed system generates 1353 kW power and overall total cost rate is 154.66 $/h. A heat recovery system is employed for power generation from a PEM fuel cell's waste heat. The proposed system involves the parallel organic Rankine cycle for utilizing the provided heat and hydrogen boil-off gas (BOG) stream as a heat sink for the cycle. Also, this stream generates power by using an expander and prepares some chilled water that enhances system performance. The PEM fuel cell as the major component of the system is modeled and then the parallel two-stage ORC (PTORC) and BOG streams are analyzed in points of the energy and exergy view. Exergoeconomic concept is applied to evaluate the economic view of the system besides energy and exergy analyses. Also, a sensitivity analysis is performed by system key parameters which provided some valuable information to comprehend the performance of the overall system. The results show that the proposed system can generate 1353 kW power. Exergoeconomic factor, energy efficiency and exergy efficiency of the overall system are computed to be 26.21%, 58.15%, and 36.64%, respectively. Also, it is concluded that the higher current density and lower operating temperature, will raise the total cost rate. [ABSTRACT FROM AUTHOR]

Highlights • Exergy, exergoeconomic and exergoenvironmental analyses were applied to an engine. • The effects of engine load and biodiesel concentration were verified. • LCA were developed for diesel and biodiesel. • Specific cost of biodiesel was higher, but presented lower environmental impacts. • Specific environmental impacts decreased with higher power or biodiesel concentration. Abstract The use of biodiesel produces less pollution than petroleum diesel, and any application that utilizes diesel fuel can use biodiesel. However, the intention is not to fully substitute petroleum diesel but to help extend the usefulness of petroleum, supporting the longevity and cleanliness of diesel engines, and possibly create a balanced energy policy. This study employed exergy, exergoeconomic and exergoenvironmental analyses to verify the effect of engine load and biodiesel concentration in a stationary, direct injection diesel engine. The Life Cycle Assessment methodology was applied within Simapro software to quantify the environmental impacts associated with the consumption of diesel and biodiesel, utilizing the Eco-indicator 99 environmental impact assessment method. Analyses included the calculation of exergy efficiency, specific cost, specific environmental impacts, and exergoeconomic and exergoenvironmental impact factors. It was verified that full load operation presented the best results in all analyses. Exergy analysis revealed that low biodiesel concentration presented slightly higher efficiency. Although the specific cost of biodiesel was double the specific cost of diesel (1.55 US$/kg versus 0.76 US$/kg), biodiesel presented lower environmental impacts (55.8 mPt/kg versus 240 mPt/kg for diesel). It was verified that exergy efficiency increased along with capacity load, but increases in the concentration of biodiesel yielded lower exergy efficiencies. The exergoeconomic factor decreased as exergy destruction and exergy losses increased, and specific environmental impacts decreased with increases in power or in biodiesel concentration. A case is made for the outstanding benefits around understanding how environmental impacts are formed to pinpoint where changes should be implemented (herein, focus is on fuel and pollutant formation). [ABSTRACT FROM AUTHOR]

Highlights • Exergoeconomic off-design model is built and the maximum deviation is less than 9% • Design of system in low-rise building relies on working condition strongly. • Component with large size is attractive for system in high-rise building. • Design for different decision variables is usually different for low-rise building. • Design for different decision variables is usually similar for high-rise building. Abstract The solar absorption-subcooled compression hybrid cooling system (SASCHCS) is subjected to the off-design operation due to the variation of solar irradiance and cooling load. Therefore, the recent design based on the specific condition is difficult to make the system cost-effective in the entire working range. This paper mainly deals with the exergoeconomic design criterion of hybrid system based on the variable working conditions to access the trade-off of investment cost and performance in the whole working condition. The SASCHCS employed in the low-rise building and the high-rise building is considered. Besides, twenty-four cases with different important parameters, i.e., the size of absorption subsystem, condenser and evaporator of compression subsystem as well as isentropic efficiency of compressor, are analyzed in detail. The product cost flow rate and relative cost difference are taken as the decision variables. The exergoeconomic off-design model is developed at first. Subsequently, the decision variables for different temperatures of hot water and cooling water as well as load level is obtained and analyzed. It is found that the difference of the design guideline for the system used in the low-rise building and high-rise building lies in the size of absorption subsystem and condenser, i.e., the lowest scale of absorption chiller is appropriate when the temperature of hot water is less than 75 °C for the facility applied in the low-rise building, but the largest size of absorption subsystem is attractive in the entire range of hot water temperature as the hybrid system is used in the high-rise building. This paper is positive for the development of design theory and helpful to design the cost-effective SASCHCS under the entire working range. [ABSTRACT FROM AUTHOR]

A parametric study is conducted for a combined cycle which combines a Gas Turbine-Modular Helium Reactor (GT-MHR) and two Organic Rankine Cycles (ORCs) to reveal the influences of decision parameters on the performance and total cost of the cycle. Two ORCs are operated from GT-MHR waste heat. Also, in order to optimize the system from both thermodynamic and economic aspects, a multi-objective optimization strategy is applied. The purpose of the optimization is to maximize the exergy efficiency and to minimize the total cost rate of the system. The selected decision variables in optimization process are the compressor pressure ratio, temperatures of inlet turbine and evaporators, temperature difference in the evaporator and degree of superheat at the inlet of the ORC turbines. After optimization, the exergy efficiency reaches 50.20% compared to 49.84% of the base case. Furthermore, it approximately reduces the capital expense by 2.4%. Distribution of the decision variables for the Pareto optimal front reveals that the degree of superheat at the inlet of the both ORC turbines has a tendency of being almost lowest value. However, the other variables reveal contrast process on the exchange between thermodynamic and economic aspects. [ABSTRACT FROM AUTHOR]

An optimized design for a solar absorption-subcooled compression hybrid cooling system used in low-rise buildings is complicated because of the overall considerations involving increases in investment costs and energy savings, which are associated with an increase in the size of the absorption subsystem. To this end, this paper’s main contribution lies in its exergoeconomic-optimized design of a solar absorption-subcooled compression hybrid cooling system employed in low-rise buildings for different design cases. In this paper, not only the minimum product-cost flow rate but also the lowest relative cost difference is taken as the objective function owing to the notable changes in fuel cost flow rates. The results of the exergoeconomic optimization shows that the actual cooling capacity of the absorption subsystem should not be designed based only on the maximum collector area. Instead, the actual installed collector area should be determined by the optimal cooling capacity of the absorption subsystem. It was also found that the optimal cooling capacity of the absorption subsystem strongly depends on solar irradiance and cooling demands. In addition, optimal sizes for the absorption subsystem should be designed according to the different minimum product cost flow rates or the lowest relative cost difference, and this difference is sensitive to the local mean solar irradiance but weakly relies on the cooling demand. The paper is helpful in its cost-effective design for a solar absorption-subcooled compression hybrid cooling system used in low-rise buildings. [ABSTRACT FROM AUTHOR]

• A novel & sustainable solution for solid waste management is presented. • Biogas fuelled gas turbine-supercritical CO 2 and steam Rankine cycle is proposed. • Energy, exergy, exergoeconomic and environmental (4-E) analysis is performed. • Digester is integrated with a thermal storage system for maximizing biogas production. • Biogas production cost curtails by at least 10% with PCM-based heating system. This work presents a novel and sustainable solution based on combined heat and power (CHP) system integrated with a simultaneous charging-discharging type thermal energy storage tank. The multi-generation system uses biogas as the heat source and is analyzed from the thermodynamic, exergoeconomic, and environmental perspectives. The proposed configuration aims to meet the electrical requirements of a cluster of 20 villages, greenhouse heating, and hot air production for agricultural drying applications. The exhaust gases from the biogas fired turbine are utilized to power a recompression supercritical CO 2 and steam Rankine cycle. The additional surplus heat is stored inside a simultaneous charging/discharging type thermal storage tank that provides favorable conditions (50–55 °C) for biogas producing microorganisms to maximizing gas production. The meso-erythritol (sugar alcohol) is used as a phase change material due to its high latent heat and large supercooling (>60 °C), suitable for the present applications. The PCM is characterized on heat flux Differential scanning calorimeter (DSC) and thermophysical properties are evaluated. Further, the exergoeconomic analysis is presented to examine the economic viability of the system which serves as a holistic solution for rural power generation. It is found that the total product unit cost of the system is 12.96 $/GJ and operating charges are 140.5 $/h. The proposed multigenerational system promises a Levelized cost of electricity at 5 ¢ /kWh. The net overall electricity generated by the system is 1432 kW and provides 200 kW of space thermal heating. In addition, hot air is produced at the rate of 9720 kg/h for different agricultural drying applications. [ABSTRACT FROM AUTHOR]

The main goal of this research is to investigate and compare the performance of three configurations of organic Rankine cycle (ORC) for binary geothermal power plants from the viewpoints of both thermodynamics and economics. The considered configurations are: Simple organic Rankine cycle (S-ORC), Regenerative organic Rankine cycle (R-ORC) and organic Rankine cycle with Internal Heat Exchanger (ORC-IHE). To assess the cycles’ performances, thermodynamic and exergoeconomic models are developed and a parametric study is carried out prior to the optimization with respect to the total product cost minimization, as the objective function. Also, a profitability evaluation of the investigated systems is performed based on the total capital investment and payback period. The results indicate that, from the thermodynamic point of view (first and second law efficiencies), the ORC-IHE has superior performance while from the economic viewpoint the S-ORC is the best case among the considered cycles. [ABSTRACT FROM AUTHOR]

Exergy analysis and exergoeconomics are often used to evaluate industrial energy systems performance from the thermodynamic and economic points of view. While the classical exergy analysis can be used to recognize the sources of inefficiency and irreversibilities, so called advanced exergy analysis is convenient for identifying real potential for thermodynamic improvements of the system by splitting exergy destruction into avoidable and unavoidable parts. In this paper, the advanced exergy analysis is used to identify performance critical components and the potential for exergy efficiency improvement of a complex industrial energy supply plant. This plant is a part of a rubber factory and its role is to provide steam, compressed air and cooling water to the production facilities, as well as hot water for space heating and sanitary use. The plant is first analyzed as is and the avoidable (and the unavoidable) part of exergy destruction is identified for each observed component. Then, the measures for removing the avoidable destruction are defined. Finally, the plant is analyzed as if the measures were implemented and avoidable losses eliminated. Numerical analysis is based on real data, some of which are collected during on site measurements. Large system of nonlinear and linear equations is defined and solved numerically using the Engineering Equation Solver. Results of the presented analysis show the difference in thermodynamic and economic operational parameters of the plant for the cases without and with the efficiency measures implemented, i.e. the current state and the state with the avoidable irreversibilities eliminated. Beside obvious increase of exergy efficiency and enhancement of other thermodynamic parameters, certain improvement in the economy of the plant could be achieved. [ABSTRACT FROM AUTHOR]

Highlights: [•] The overall energy and exergy efficiencies of the plant is found to be 59.37% and 38.99% respectively. [•] Performance assessment of a cement plant indicates that the calcination process involves the highest portion of energy losses. [•] The specific exergetic cost cement produced by the cement plant is calculated to be 180.5USD/GJ. [•] The specific cement manufacturing cost is found to be 41.84USD/ton. [Copyright &y& Elsevier]

Highlights: [•] Energy, exergy and exergoeconomic analysis of a complete cement plant have been investigated. [•] The first and second law efficiencies based on the energy and exergy analysis are defined for the entire cement plant. [•] The specific energy consumption of the whole sections of the cement plant have been analyzed. [•] The specific manufacturing costs of farine, clinker and cement have been determined by the cost analysis. [Copyright &y& Elsevier]

Abstract: In this part II of the study, three new trigeneration systems are examined. These systems are SOFC-trigeneration, biomass-trigeneration, and solar-trigeneration systems. This study reveals that the maximum trigeneration-exergy efficiencies are about 38% for the SOFC-trigeneration system, 28% for the biomass-trigeneration system and 18% for the solar-trigeneration system. Moreover, the maximum cost per exergy unit for the SOFC-trigeneration system is approximately 38$/GJ, for the biomass-trigeneration system is 26$/GJ, and for the solar-trigeneration system is 24$/GJ. This study reveals that the solar-trigeneration system offers the best thermoeconomic performance among the three systems. This is because the solar-trigeneration system has the lowest cost per exergy unit. Furthermore, the solar-trigeneration system has zero CO2 emissions and it is based on a free renewable energy source. [Copyright &y& Elsevier]

Abstract: This part I of the study presents the thermoeconomic optimization formulations of three new trigeneration systems using organic Rankine cycle (ORC): SOFC-trigeneration, biomass-trigeneration, and solar-trigeneration systems. A thermoeconomic modeling is employed using the specific exergy costing (SPECO) method while the optimization performed using the Powell’s method to minimize the product cost of trigeneration (combined, cooling, heating, and power). The results help in understanding how to apply the thermoeconomic modeling and thermoeconomic optimization to a trigeneration system. [Copyright &y& Elsevier]

Abstract: In this paper, a comprehensive exergoeconomic analysis of a 10 kW PEM fuel cell at various operating temperatures, pressures, cell voltages and air stoichiometries is performed. The analysis is performed at fuel cell operating temperatures (T/To) and pressures (P/Po) ranging from 1 to 1.25 and 1 to 3, respectively. In addition, the calculations are performed on typical fuel cell operating voltages of 0.5 V and 0.6 V and at air stoichiometries of 2, 3 and 4 in order to determine their effects on the exergy cost of the fuel cell. The calculated results demonstrated the significance of the operating pressure, cell voltage and air stoichiometry on the exergy cost of the fuel cell. Furthermore, lower capital cost of the fuel cell, annual O & M cost and hydrogen cost could contribute to a drastic reduction in the exergy cost. Thus, a substantial improvement in the overall results could be achieved. [Copyright &y& Elsevier]

This paper deals with the increase of cost effectiveness in the design of thermal power plants and presents a combination of the iterative exergoeconomic optimization technique with fuzzy inference systems (FIS). The development of FIS for the iterative exergoeconomic evaluation and improvement of plant components is described. An application to the iterative cost minimization of a simple cogeneration plant is discussed. Several case studies show that the application of fuzzy logic in exergoeconomics is very useful. [Copyright &y& Elsevier]

To evaluate the thermodynamic performance and cost effectiveness of thermal systems and to estimate the potential for improvements, it is always useful to know (a) the avoidable part of an exergy destruction and (b) the avoidable investment cost associated with a system component. Improvement efforts should then focus only on these avoidable parts.Using a cogeneration system as an example, this paper discusses how to estimate the avoidable and unavoidable exergy destruction and investment costs associated with compressors, turbines, heat exchangers and combustion chambers. This general procedure, although based on many subjective decisions, facilitates and improves applications of exergoeconomics. [Copyright &y& Elsevier]

• Analysis of Supercritical Organic Rankine Cycle operating on hydrocarbons. • Energy and Exergy analysis of the cycle were assessed for a low-grade heat source. • Specific Exergy Costing method was used for Exergoeconomic analysis of the system. • Working fluid based on various cycle parameter performance was selected for system. In this paper, several hydrocarbons' performance as a working fluid for a supercritical Organic Rankine Cycle are studied. Energy, exergy, and exergoeconomic analysis are conducted for the cycle operating with a low-grade waste heat source. Initially, fifteen different working fluids, primarily hydrocarbons, were considered based on their environmental characteristics, global warming potential, ozone depletion potential, flammability, and toxicity. The cycle efficiency for each working fluid was analyzed for different cycle operating pressures and different inlet heat source temperatures from 400 K to 500 K for a constant turbine work output. Three different trends of cycle performance characteristics were observed for various working fluids with the cycle operating at different evaporator pressures and source inlet temperatures. The working fluids that exhibited similar characteristic trends were then categorized into families for further analysis. Three hydrocarbons, i.e., Dimethyl Ether, R1234yf, and Diethyl Ether, were each selected as the representative of their respective family, along with Isobutane as the reference working fluid for comparison. After detailed energy and exergy analyses, Dimethyl Ether and Isobutane were found to be promising working fluids for the range of pressure and source inlet temperatures considered. Finally, the exergoeconomic analysis showed Dimethyl Ether to be the optimal working fluid based on the unit cost of net work produced and the total cost of exergy destruction, which were calculated to be (59.18 ± 0.49) $/MWh and (8.92 ± 0.48) $/h, respectively, when operating at 450 K. [ABSTRACT FROM AUTHOR]

• Production of biofuels using HEFA and ATJ routes. • Biorefinery configurations to evaluate biofuel production from palm oil. • Evaluation of biorefineries using thermodynamics and exergoeconomics tools. • Integral methodology to guide decision making in the use of biomass for biorefineries. • Life Cycle Assessment of the main products was carried out. This work explores palm oil and the residual biomass from oil palm extraction to obtain valuable products via sustainable routes in integrated biorefineries, which were separated into three scenarios: Baseline Scenario is the current Brazilian application of palm in the energy sector using a biodiesel plant with a cogeneration system; Scenario 1 integrates a Hydrotreatment of Esters and Fatty Acids unit to produce bio-jet fuel into the previous case; and Scenario 2, integrates a second-generation ethanol plant and an Alcohol-to-Jet process in order to obtain bio-jet fuel from the second generation. Taking into account that the selection and integration of processes carried out in a biorefinery would impact the overall efficiency of the system, the production costs and the impacts on the environment of the plant make it is necessary to carry out a comprehensive evaluation of the system that allows characterizing and quantify the energy, economic and environmental aspects related to the biomass energy conversion. A methodology of analysis was proposed to address all of these aspects and to provide results that allow for a decision-making guide in technology selection. It was identified that the main need for improvement in the biorefineries relies on cogeneration, which exergy destruction rate ranged from 167.99 to 213.63 MW. The unit exergoeconomic costs founded for glycerol, biodiesel, and electricity were all lower than the market costs, the bio-jet fuel costs, from hydrotreatment, were nearly the same as those from the Brazilian market 0.49 and 0.46 USD/L, respectively. However, the costs of upgrading ethanol were the highest found and way higher than the market rate at 5.15 USD/L. Environmentally, the selected configuration of biorefineries provides all produced biofuel environmental gains compared to conventional non-renewable fuels. Biodiesel and bio-jet fuels would avoid emission of 324.65 kgCO 2eq /t and 3092.45 kgCO 2eq /t, respectively. [ABSTRACT FROM AUTHOR]

• Two novel geothermal energy-based tri-generation cycles are proposed. • The cycles generate power and produce hydrogen and freshwater. • Thermodynamic and exergoeconomic analyses are carried out. • The tri-generation system based on the double flash has better performance. • Multi-objective optimal design results in the most promising condition. Thermodynamic and exergoeconomic analysis of two novel tri-generation systems based on single and double flash are reported to generate power and produce hydrogen and freshwater from geothermal energy. Both proposed cycles use the organic Rankine cycle to generate power, proton exchange membrane electrolyzer to produce hydrogen and reverse osmosis desalination to produce freshwater. The proposed cycles are assessed based on the thermodynamic and exergoeconomic approaches. Different single-objective optimizations are done to maximize produced power and thermal and exergy efficiencies as well as minimize power production cost. Multi-objective optimization is also performed based on weight coefficients. Moreover, the thermodynamic and exergoeconomic parameters of the proposed systems in different conditions are investigated through a comprehensive parametric study. The results showed that the tri-generation system based on the double flash (system 2) has better performance from the exergy and exergoeconomic viewpoints compared to the single flash-based one (system 1) so that the optimum values of 8613 kW, 2.308 kg/hr, 9.502 kg/s, 12.96%, 53.79%, and 5.845 $/GJ are obtained for net power output, hydrogen production rate, desalinated water rate, energy and exergy efficiencies, and power specific cost of this system at the geofluid temperature of 200 ℃. [ABSTRACT FROM AUTHOR]

• Thermal drying is the system component with the lowest exergy efficiency. • Increasing the heating system temperature performance of the system increases. • When the geo-fluid increase by 50 °C, drying and electricity costs vary by 19% and 28% respectively. • Minimum hourly exergoeconomic cost is got when geo-fluid is 110 °C and recycled fraction is 59%. • Cost of sludge drying with geothermal energy is similar to that with solar energy. The highest economic and environmental costs of wastewater treatment plants are related to waste disposal, which is mainly sludge disposal, and energy supply. Such challenges are even more critical in islands, where there are many environmental, landscape, and geographical constraints that make the use of conventional technologies difficult. For this reason, a geothermal energy system for wastewater and sludge treatment, and power production is proposed. Such a system is assessed through an exergoeconomic analysis, performed in Engineering Equation Solver environment, that allows determining the exergoeconomic costs of geo-fluid, electricity production, and sludge drying. The sensitivity analyses, carried out to assess the effect of several design parameters, have highlighted that the geothermal source temperature significantly affects the system operation and consequently the exergoeconomic costs, which range 77–95 c€/kWh ex for sludge treatment and between 4.8 and 6.6c€/kWh ex for electricity production. Finally, multivariate optimization has been carried out to find the conditions that minimize the exergoeconomic costs of the system. The total hourly exergoeconomic cost of the system products, namely sludge and electricity, is minimized when the geothermal source temperature is equal to 110 °C and the 58.91% of the desiccant flow is recycled. Overall, this study outlines that an exergy-based economic analysis is fundamental to assess the economic viability of innovative integrated solutions based on renewables. [ABSTRACT FROM AUTHOR]

• A novel use of Exergoeconomics to optimize multiple-chillers systems is proposed. • The method represents support for decision-making at the design and operational stage. • Design options regarding chillers' size and parallel or series configurations are compared. • Operational strategies based on "symmetric" and "sequential" loading of chillers are examined. • The lowest unit exergoeconomic cost identifies the best design or operation strategy. Multiple-chillers systems represent viable solutions for medium/large-scale air conditioning applications characterized by variable cooling demand. The energy efficiency of such systems is influenced by the number of chillers, the combination of cooling capacities, and the load-sharing among the units. Large efforts have been devoted to developing efficient operation strategies for these systems, but rules of thumb are usually adopted for selecting cooling capacities thus leaving room for energy and economic savings. In this paper, exergoeconomic analysis is proposed as a promising method to identify near-optimal design and operation strategies, due to the capability of exergoeconomic indicators to account simultaneously for capital and operating costs. The potential of the method is illustrated for a hydronic system supplying an air-handling unit installed in an office building. Design alternatives are compared, with chillers of equal or different capacities operated in a parallel or series configuration, and the cost-effectiveness of different load sharing strategies is also investigated. A thermoeconomic model for multiple-chillers systems is formulated, considering the actual performance of chillers under full- and part-load conditions derived by a plant simulator. Results show that the exergoeconomic cost of chilled water reduced by about 7% and 30% when passing from evenly to unevenly sized systems in both series and parallel configurations. It is also found that the symmetric load sharing strategy leads to a 14–18% reduction in the cost of chiller water compared to the sequential one. The study confirms that this method may represent systematic and thermodynamically-sound support for engineers in this field. [ABSTRACT FROM AUTHOR]

• Two novel co-generation systems are presented to produce fresh water, and hydrogen. • Exergoeconomic analysis is applied to evaluate the system in both modes. • Using multi-objective optimization, optimum design parameters are determined. • In the optimal mode, the overall exergy efficiency is 22.49%. This article presents the exergoeconomic evaluation of a new geothermal-based integrated system, which produces hydrogen and freshwater. The proton exchange membrane electrolyzer (PEME) and humidifier-dehumidifier (HDH) units are responsible for hydrogen and freshwater production, respectively. Kalina cycle and thermoelectric generator (TEG) provide the needed electricity to run the PEME. As both TEG and HDH work with low-temperature waste heat of the Kalina cycle and geothermal water, two different configurations for the suggested system are proposed, and evaluated by the exergoeconomic analysis. Levelized cost of evaluation (LCoE) also compares the suggested configurations with fossil fuel power plants, while the effects of various critical parameters of the system are evaluated in the parametric study. Since there are uncertainties about decision parameters, single- and multi-objective optimizations with properly defined objectives are performed to achieve the best performance in each operating mode. Optimization studies revealed that the optimal mode is superior in terms of exergy efficiency, freshwater cost, and hydrogen cost with the values of 22.49%, 2.94 $/m3 and 7.37 $/kg, respectively. [ABSTRACT FROM AUTHOR]

• A novel cogeneration system based on compressed air energy storage system. • The reliability analysis through applying the state space and Markov method. • The effect of the operational period on the payback time and final profit of the system. • An environmentally-friendly, high efficiency and economical cogeneration system. • The Grassman exergy flow diagram of the proposed cogeneration system. In the succeeding of our recent article, exergoeconomic analysis with reliability and availability considerations is studied for a cogeneration system composed of compressed air energy storage, organic Rankine cycle, and absorption-compression refrigeration cycle. During off-peak times, surplus and cheap electricity of the grid or renewable energy sources is used to provide pressurized air and heating capacity in the energy storage subsystem, which are efficiently exploited to tackle two imperatives during peak demand periods: addressing power shortages and chilled water production at the same time. Reliability consideration is incorporated through Markov method in exergoeconomic to scrutinize the cost variations of the products for achieving a more realistic cost, providing superior alternatives for decision-making and economic design. The effects of the critical parameters such as electricity purchase price, diurnal operating period, and failure and repair rates on the cost of the products have been analyzed. The results indicate that the cost of electricity and chilled water are respectively 0.0783 $/kWh and 0.1789 $/kWh during peak period, which augmented by 8.36% and 8.32% with reliability consideration. The economic analysis reveals that the proposed system has a payback time of 2.9 years, whereas it is extended to around 3 years with reliability consideration, as a more reliable and authentic payback time. [ABSTRACT FROM AUTHOR]

• A coupling of supercritical power and transcritical refrigeration CO 2 cycle are evaluated. • The multi-generation system produces power, refrigeration, and heating. • Exergoeconomic evaluation and optimization has been conducted. • The evaluation and optimizations are conducted for different operating conditions. • Heat cost is sensitive to operating conditions; refrigeration cost is the highest. A combined cycle coupling a supercritical power cycle with a transcritical refrigeration cycle with carbon dioxide as working fluid is evaluated and optimized from the exergoeconomic viewpoint. The system is designed to produce power, refrigeration, and heating simultaneously. If no net power is generated, the system can be described as a cogeneration. First, the cogeneration system working with various evaporation temperatures is optimized for having the lowest average cost of the products, which indicates that the system is preferred to operate at the lower evaporation temperature. Then for tri-generation, by increasing the power output and the pressure merging two sub-systems, the cost of the products (average and individual) reduces and the efficiency of the overall system increases. In addition, the cost of the power is the lowest while the cost of the refrigeration is the highest, and the cost of the heating is sensitive to the operation conditions of the overall system. [ABSTRACT FROM AUTHOR]