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The design of solid oxide fuel cells (SOFC) using biogas for distributed power generation is a promising alternative to reduce greenhouse gas emissions in the energy and waste management sectors. Furthermore, the high efficiency of SOFCs in conjunction with the possibility to produce hydrogen may be a financially attractive option for biogas plants. However, the influence of design variables in the optimization of revenues and efficiency has seldom been studied for these novel cogeneration systems. Thus, in order to fulfill this knowledge gap, a multi-objective optimization problem using the NSGA-II algorithm is proposed to evaluate optimal solutions for systems producing hydrogen and electricity from biogas. Moreover, a mixed-integer linear optimization routine is used to ensure an efficient heat recovery system with minimal number of heat exchanger units. The results indicate that hydrogen production with a fuel cell downstream is able to achieve high exergy efficiencies (65–66%) and a drastic improvement in net present value (1346%) compared with sole power generation. Despite the additional equipment, the investment costs are estimated to be quite similar (12% increase) to conventional steam reforming systems and the levelized cost of hydrogen is very competitive (2.27 USD/kgH2).

Current study deals with performance evaluation of the solar power tower driven recompression with main compressor intercooling (RMCIC) supercritical CO2 cycle incorporating the parallel double evaporator organic Rankine cycle (PDORC) as bottoming cycle using low global warming potential fluids to reduce the global warming and ozone depletion. Using the PDORC instead of the basic organic Rankine cycle, waste heat from the intercooler and cycle exhaust were recovered simultaneously to enhance performance of the standalone RMCIC cycle. Exergy, thermal efficiency, efficiency improvement and waste recovery ratio were considered as performance parameters. A computer program was made in engineering equation solver to simulate the model. It was concluded that by the incorporation of the PDORC thermal efficiency was improved by 7–8% at reference conditions. Maximum combined cycle's thermal and exergy efficiency were found 54.42% and 80.39% respectively of 0.95 kW/m2 of solar irradiation based on R1243zf working fluid. Among the results it was also found that maximum waste heat was recovered by the R1243zf about 54.22 % at 0.95 effectiveness of low temperature recuperator.

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 this research paper, comprehensive thermodynamic modeling of an integrated energy system consisting of a multi-effect desalination system, geothermal energy system, and hydrogen production unit is considered and the system performance is investigated. The system's primary fuel is a geothermal two-phase flow. The system consists of a single flash steam-based power system, ORC, double effect water–lithium bromide absorption cooling system, PEM electrolyzer, and MED with six effects. The effect of numerous design parameters such as geothermal temperature and pressure on the net power of steam turbine and ORC cycle, the cooling capacity of an absorption chiller, the amount of produced hydrogen in PEM electrolyzer, the mass flow rate of distillate water from MED and the total cost rate of the system are studied. The simulation is carried out by both EES and Matlab software. The results indicate the key role of geothermal temperature and show that both total exergy efficiency and total cost rate of the system elevate with increasing geothermal temperature. Also, the impact of changing absorption chiller parameters like evaporator and absorber temperatures on the COP and GOR of the system is investigated. Since some of these parameters have various effects on cost and efficiency as objective functions, a multi-objective optimization is applied based on a Genetic algorithm for this system and a Pareto-Frontier diagram is presented. The results show that geothermal main temperature has a significant effect on both system exergy efficiency and cost of the system. An increase in this temperature from 260 C to 300 C can increase the exergy efficiency of the system for an average of 12% at various working pressure and also increase the cost of the system by 13%.

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.

The main purpose of the current research work is to suggest a novel integrated multi-generation energy system and scrutinize 4E evaluation. This system consists of a solid oxide fuel cell, a PEM electrolyzer for hydrogen production, and an ejector-based absorption chiller for the coefficient of performance improvement. All parts of this system are verified with existing reports and papers. Effect of fuel cell current density, SOFC fuel cell temperature, absorption chiller evaporator temperature, and condenser temperature, and outlet turbine pressure has been investigated and reported. The effect of mentioned parameters on the exergy and cost rate has been considered. Data illustrate that the maximum exergy destruction rate belongs to the SOFC contributing 60% of the total exergy destruction rate of the system. Under the given condition of the system, the net produced power is about 200 kW with an exergy efficiency of 30.2% and thermal efficiency of 60.4%. At the considered condition the total cost rate of the system is estimated about 22.29 $/hr. The results of the present work provide a scientific base for designing poly-generation systems with high efficiency and reasonable cost rate.

In this present research study a multi-generation energy system which is coupled with CO2 capture unit which is based on Rankine cycle, organic Rankine cycle, ejector cooling system and absorption chiller has been analyzed via energy, exergy, exergy-economic aspects by developing MATLAB, also to achieve the optimum operating condition genetic algorithm has been applied for system optimization. The objective of this study is to propose an optimized efficient integrated energy system to recycle the energy waste of a typical industrial factory. The optimization has been illustrated on a Pareto frontier to achieve the optimum scheme of the multi-generation system regarding technical and economic viewpoints. Results indicate the optimal condition of this system has occurred at 0.37 exergy efficiency with 0.03 $/s. Furthermore, by surging the mass flow rate of waste gases up to 70 kg/s, net power output augmented up to 7500 kW. Besides, hydrogen production and produced desalinated water rise up to 8.5 g/s and 16 kg/s, respectively.

A novel biomass-driven heat and power cogeneration system comprising biomass gasification, a gas turbine, a Stirling engine, and a supercritical carbon dioxide cycle integrated with a domestic water heater was proposed in this work. Different biomass feedstocks (paper, wood, paddy husk, and municipal solid waste) were used in the gasifier as the input fuel. The devised system was analyzed from energy, exergy, exergoeconomic, and environmental viewpoints. Moreover, the effect of integrating the Stirling engine with the stand-alone CHP system is studied. Moreover, a detailed parametric analysis was performed to assess the effect of varying operating parameters on system efficiency. Finally, multi-objective optimization using genetic algorithm in MATLAB software was performed to obtain the optimum operating points. According to the results, using municipal solid waste as the input biomass resulted in the highest exergy efficiency by 41.36 % and the lowest C O 2 emission by 0.9021 t / M W h . Also, the system with the Stirling engine had a higher exergy efficiency and lower C O 2 emission than the system without the Stirling engine. According to the optimization results, the maximum obtainable exergy efficiency was 42.03 % , which was related to MSW. Also, the minimum achievable c p , t o t was 10.94 $ / G J , attributable to the respective paddy husk.

The use of lower global warming potential refrigerants as an alternative to hydrochlorofluorocarbons and hydrofluorocarbons from an environmental perspective is the need of an hour. The feasibility and possibility of alternative refrigerants in the existing refrigeration system can be recognized using exergy assessment. This will lead to improving the thermal performance of the refrigeration systems. In this paper, exergy assessment of a multistage multi-evaporator vapor compression refrigeration system is performed using the Simulink model. A total of eighteen refrigerants are considered for the analysis from the environmental perspective, safety considerations, etc. The evaporator-1, evaporator-2, and condenser temperatures are varied from 0 °C to 15 °C, −15 °C to −5 °C, and 25 °C to 33 °C respectively. The highest exergy destruction among all the components is found for both the compressors, followed by the condenser, evaporators, expansion devices, and internal heat exchanger. Refrigerants R141b, R123, R245ca, R245fa, and R152a showed better thermal performance than hydrofluoroolefins refrigerants, but have high GWP values. R1234ze(E), and R1234yf are environmentally friendly and achieved similar performance to conventional refrigerants.

Based on the “three box” exergy analysis model, a black box-gray box hierarchical exergy analysis and evaluation method is put forward in this paper, which is applied to evaluate the power generation technology of differential pressure produced by natural gas expansion. By using the exergy analysis theory, the black box - gray box hierarchical exergy analysis models of three differential pressure power generation technologies are established respectively. Firstly, the “black box” analysis models of main energy consuming equipment are established, and then the “gray box” analysis model of the total system is established. Based on the calculation results of exergy analysis indexes, the weak energy consumption equipment in the whole power generation process is accurately located. Taking a gas field in southwest China as an example, the comprehensive energy consumption evaluation of the three power generation technologies is carried out, and the technology with the best energy consumption condition among the three technologies is determined. Finally, the rationalization improvement measures are put forward from improving the air tightness, replacing the deflector and reducing the flow loss.

Renewable energy-based hydrogen production plants can offer potential solutions to both ensuring sustainability in energy generation systems and designing environmentally friendly systems. In this combined work, a novel solar energy supported plant is proposed that can generate hydrogen, electricity, heating, cooling and hot water. With the suggested integrated plant, the potential of solar energy usage is increased for energy generation systems. The modeled integrated system generally consists of the solar power cycle, solid oxide fuel cell plant, gas turbine process, supercritical power plant, organic Rankine cycle, cooling cycle, hydrogen production and liquefaction plant, and hot water production sub-system. To conduct a comprehensive thermodynamic performance analysis of the suggested plant, the combined plant is modeled according to thermodynamic equilibrium equations. A performance assessment is also conducted to evaluate the impact of several plant indicators on performance characteristics of integrated system and its sub-parts. Hydrogen production rate in the suggested plant according to the performance analysis performed is realized as 0.0642 kg/s. While maximum exergy destruction rate is seen in the solar power plant with 8279 kW, the cooling plant has the lowest exergy destruction rate as 1098 kW. Also, the highest power generation is obtained from gas turbine cycle with 7053 kW. In addition, energetic and exergetic efficiencies of solar power based combined cycle are found as 56.48% and 54.06%, respectively.

Energy enhancement and utilization of renewable energy sources have become inevitable solutions for the concerns of fossil fuel depletion and global warming. Two different cogeneration systems are proposed for cooling and power generation. A gas turbine and an ejector refrigeration cycle are employed in the configurations, in which gas turbine cycle uses biogas as the required fuel. First, these two configurations are analyzed from energy and exergy perspectives. A comprehensive parametric study is also performed by decision variables for the optimization. Results reveal that both energy and exergy efficiencies of conventional combined gas turbine/ejector refrigeration cycle can be improved up to 44.6% and 33.54%, respectively. Besides, the outcomes of the parametric study point out that the combustion chamber has a significant effect on energy and exergy efficiencies and can increased them about 10%. Also, it is found that the vapor generator accounts for the highest exergy destruction among all components. Moreover, by using a genetic algorithm as an optimization method, the thermal and exergetic efficiencies of the base system improves. In the best operating condition, the thermal and exergetic efficiencies of the system reach 57.11% and 36.68%, respectively.

The present study investigates the advanced exergy assessment in a solar absorption power cycle to reveal the inefficiency of the system. Unlike simple exergy assessment, which only assesses exergy destruction, advanced exergy evaluates avoidable, unavoidable, exogenous, and endogenous exergy destructions. EES software is employed to model the proposed absorption power cycle, in which the power is generated using a low-temperature heat source driven by solar energy. The novelties of the present study are the use of solar energy in absorption power and applying the advanced exergy assessment. According to the results, the total energy and exergy efficiencies are 6.655% and 7.011% in the real state, 8.517% and 8.973% in the unavoidable state, and 9.433% and 9.938% in the ideal state, respectively. In other words, both efficiencies improve by 41.7% and 10.75% under ideal and unavoidable conditions compared to the real state, respectively. The outcomes reveal that the unavoidable exergy destruction is greater than the avoidable exergy destruction in the constituents, implying that no structural refinement can be effective in the system. Among the components, 73.69 kW exergy destruction occurs in the solar collector, of which 67.47 kW is endogenous destruction. Also, the unavoidable and avoidable exergy destructions equal 73.03 kW and 0.66 kW in the solar collector, respectively. Moreover, the unavoidable endogenous part accounts for the highest proportion of exergy destruction in the solar collector, while the avoidable exogenous destruction is less than zero. It means that by improving the component itself, it is possible to reduce the exergy destruction.

In industrial engineering, hydrogen is usually transported and stored after being liquefied, which is an energy-intensive process. Aiming to liquefy hydrogen with high efficiency and low consumption, a novel hydrogen liquefaction process based on dual-path hydrogen refrigeration is proposed innovatively and simulated by Aspen HYSYS to determine the key parameters. Taking the specific energy consumption (SEC) as the objective function for the optimization by genetic algorithm (GA), optimum parameters could be obtained. Meanwhile, the single variable method is conducted to analyze the impact of key parameters on process characteristics. Under the premise of complete liquefaction, the SEC, coefficient of performance (COP) and exergy efficiencies (EXE) of the proposed system are 7.041 kWh/kg LH2, 0.1834, 0.5413, respectively. Compared with the other three hydrogen liquefaction systems simulated under the same conditions, they are decreased by 22.16% and increased by 33.58% and 42.37%, respectively. The results show that the proposed system shows better performance under lower consumption.

The paper aims to solve drawbacks associated with Gas Turbine GT by integrating a novel cascaded system into a combined cycle simultaneously. Parabolic trough collectors preheat the air at the combustion chamber inlet, then drive an absorption inlet-air cooling cycle that controls the ambient-air temperature at the compressor's inlet. This study uses the 2nd law of thermodynamics to estimate the maximum available energy, calculate the electric exergy efficiency, and explore the maximum irreversible exergy destruction in the system's components. Artificial Neural Network was employed to develop a multi-objective optimization by linking data collected from equations in the Engineering Equation Solver software with Matlab. Spider diagrams investigated the effect of varying several key operating parameters on the performance of the system, identifying gas turbine as the highest irreversibility sub-unit and the solar field parabolic trough collectors as the second. Design improvement for the combustion chamber can reduce 303.6 MW, and for parabolic trough collectors field reduce 58.9 MW. Artificial neural networks with multi-objective optimization maximized the electric exergy destruction to 46.19% and minimized the exergy destruction to 489.4 MW, relative to the corresponding values from the simple design point.

In this study, an optimal scheme is proposed by utilizing waste streams at a plant-wide scale along with pressure retarded osmosis (PRO) membrane allocation in complex industrial networks for energy recovery. Chemical exergy pinch analysis (ChExPA) and process graph (P-graph) are used to address the problem. The ultimate goals of utilizing the tools are (1) determine the optimal external load consumption, (2) minimizing the waste discharge, and (3) sustainable energy production while utilizing high chemical exergy potential waste discharges. A reliability assessment assisted with Monte-Carlo simulation is further performed to evaluate the proposed solutions from P-graph considering uncertainties. The effectiveness of the proposed methodology is explained using three industrial case studies which covered both intra-plant and inter-plant networks. The results indicated that ChExPA and P-graph can effectively identify the optimal location of the PRO membrane in industrial networks. Upon analyzing the complex inter-plant industrial networks 7.795 MW net power output was harnessed, and significantly higher waste of 384.92 kg/s was recovered with a levelized cost of energy of 0.073 $/kWh. The inter-plant network shows the greatest net profit which accounted for approximately $1,191,000 (i.e., 5.84 times higher than stand-alone plants) with a reasonable payback-period of 4.5 years.

Energy quality in each country is one of the important indicators of economic development, Which affects the economic growth of that country. Exergy analysis, considering all flow properties including pressure, temperature, composition, is a powerful way to evaluate the energy consumption of equipment such as natural gas and liquefied gas plants. Inefficiency of a system can be defined by the conventional exergy analysis method, While, irreversible resources and real potentials for system improvement can only be identified by the advanced exergy analysis method. This analysis splits conventional exergy destruction into two exogenous and endogenous parts according to origin, and also unavoidable and avoidable parts according to the ability to remove and modifications. In this method, the exergy concept was separated by considering the ideal and avoidable condition assumptions. As a real case study, a natural gas liquid plant 800, from National Iranian South Oil Company located in southwest of Iran was considered to be investigated by conventional exergy analysis, advanced exergy analysis methods. The results of conventional exergy analysis illustrated that the highest amount of exergy destruction belonged to compressor and heat exchanger with 509.99 and 629.04 kW, respectively. However, in the case of heat exchanger, despite having the highest rate of exergy destruction, it is not considered in modification priorities due to its low avoidable exergy destruction value. Also, advanced exergy analysis suggested that the exergy destruction of the compressor and heat exchanger will be reduced by improving performance of these components.

In this study, two wind-solar-based polygeneration systems namely CES-1 and CES-2 are developed, modeled, and analyzed thermodynamically. CES-1 hybridizes a heliostat based CSP system with wind turbines while CES-2 integrates heliostat-based CPVT with wind turbines. This study aims to compare the production and thermodynamics performance of two heliostat based concentrated solar power technologies when hybridized with wind turbines. The systems have been modeled to produce, freshwater, hot water, electricity, hydrogen, and cooling with different cycles/subsystems. While the overall objective of the study is to model two polygeneration systems with improved energy and exergy performances, the performances of two solar technologies are compared. The wind turbine system integrated with the comprehensive energy systems will produce 1.14 MW of electricity and it has 72.2% energy and exergy efficiency. Also, based on the same solar energy input, the performance of the heliostat integrated CPVT system (CES-2) is found to be better than that of the CSP based system (CES-1). The polygeneration thermal and exergy efficiencies for the two systems respectively are 48.08% and 31.67% for CES-1; 59.7% and 43.91% for CES-2. Also, the electric power produced by CES-2 is 280 kW higher in comparison to CES-1.

The high-temperature heat pump steam system (HTHPS) is an effective way to replace the calcining boiler's steam. However, the large temperature span of the system leads to colossal exergy loss of refrigerant in expansion valves and other components. Therefore, it is hoped to adopt the dual-flash vaporization process to improve the system's steam production performance. In this paper, three thermodynamic models and exergy models of HTHPS with a double flash evaporation process are established. Furthermore, this paper uses the multivariate simulated annealing algorithm to calculate the optimal COP of the system. Then, by comparing the single-stage compression (SC) system and the quasi-two-stage compression (QTC) system, the influence of the dual-flash vaporization process on HTHPS is analyzed. The results show that under the same environment, the COP of the dual-flash vaporization process compression system is 23.8% 44.54% higher than that of the SC system. With the increase of the system temperature span, the flash steam supplemental process brings the system to improved thermodynamic performance. Moreover, the exergy model of the dual-flash system is closest to the reversed Carnot cycle, when the evaporation temperature is 50 °C and the condensing temperature is 110 °C.

In this paper, a proposal for a novel integrated Brayton cycle, supercritical plant, trans critical plant and organic Rankine cycle-based power systems for multi-generation applications are presented and analyzed thermodynamically. The plant can generate power, heating-cooling for residential applications, and hydrogen simultaneously from a single energy source. Both energetic and exergetic analyses are conducted on this multi-generation plant and its subsystems in order to evaluate and compare them thermodynamically, in terms of their useful product capabilities. The energetic and exergetic effectiveness of the multi-generation system are computed as 44.69% and 42.03%, respectively. After that, a parametric study on each of the subsystems of the proposed combined system is given in order to provide a deeper understanding of the working of these subsystems under different states. Lastly, environmental impact assessments are provided to raise environmental concerns for several operating conditions. For the base working condition, the results illustrate that the proposed plant has 0.5961, 0.0442, 0.6265 and 1.678 of exergo-environmental impact factor, exergy sustainability index, exergy stability factor and sustainability index, respectively.

The present paper introduces a novel latent heat storage system applicable to hot water systems equipped with a Phase Change Material (PCM) and a Novel set of Blossom-Shaped Fins (BSFs). The water supplied by the collector is injected into the heat exchanger as a Heat Transfer Fluid (HTF). The PCM is charged during the daytime and will be reused as a primary system to supply the building's heating load at nighttime. The system's performance is investigated for various geometrical parameters, including the fin-number, fin's degree of compactness, fin-height, and the combined-fin heights/pin. Moreover, thermodynamic optimization through exergy analysis is applied to give better insights into the system's performance and efficiency. Results imply that both the variations of the fin-number and the fin's degree of compactness improve the charging time by 17% and 2%, respectively. Moreover, the fin-number variations positively affect the exergy efficiency by 6%, while compactness of fins shows a converse behavior with an 8% reduction in the exergy efficiency. On the other hand, the fin height/pin parameter variations improve the melting performance by 15% while having fewer exergy efficiencies. In addition, reducing the fin-height parameter improves the exergy efficiency of the case with the least melting time by 25% while associated with the most prolonged melting duration. Hence, considering the different impacts of geometric parameters on the exergy efficiency and the storage time, one should pay attention to the designer's view and climate conditions to choose the suitable heat exchanger based on the desired application. If the storage time is limited, the combined fin height/pin is preferred. Otherwise, the fin-height might be a better candidate to achieve higher exergy efficiencies and system performance.

This work considers an analysis using energy and exergy of turbines for a coal-based conventional steam power plant of 500 MW under the Damodar Valley Corporation (DVC), India to optimize its operating conditions. An effort has also been made to control the environmental emission of different gases from the plant. Hence, a control volume is assumed consisting of a high-pressure turbine (HPT), an intermediate turbine (IPT), and a low-pressure turbine (LPT) of the plant. A thermodynamic-based model is considered in determining the performance of turbines in the power cycle under various unit loads (60%, 80%, and 100%). This analysis includes a prediction of energy, then exergy, and related irreversibility of flow stream to and from said control volume under the unit load conditions. The improvement in heat rate of the turbine with an increase in load is also estimated. As found, the heat rate reaches a minimum when the plant operates at higher unit loads (80% and 100%), which is an economical condition of operation. With the basis of the improved heat rate, a reduction in coal consumption, plant ash generation, also SO2 and CO2 emissions by the plant are estimated.

A novel solid oxide fuel cell (SOFC) multigeneration system fueled by biogas derived from agricultural waste (maize silage) is designed and analyzed from the view point of energy and exergy analysis. The system is proposed in order to limit the greenhouse gas emissions as it uses a renewable energy source as a fuel. Electricity, domestic hot water, hydrogen and cooling load are produced simultaneously by the system. The system includes a solid oxide fuel cell; which is the primary mover, a biogas digester subsystem, a cascaded closed loop organic Rankine cycle, a single effect LiBr-water absorption refrigeration cycle, and a proton exchange membrane electrolyzer subsystem. The proposed cascaded closed-loop ORC cycle is considered as one of the advanced heat recovery technologies that significantly improve thermal efficiency of integrated systems. The thermal performance of the proposed system is observed to be higher in comparison to the simple ORC and the recuperated ORC cycles. The integration of a splitter to govern the flue gas separation ratio is also introduced in this study to cater for particular needs/demands. The separation ratio can be used to vary the cooling load or the additional power supplied by the ORC to the system. It is deduced that net electrical power, cooling load, heating capacity of the domestic hot water and total energy and exergy efficiency are 789.7 kW, 317.3 kW, 65.75 kW, 69.86% and 47.4% respectively under integral design conditions. Using a parametric approach, the effects of main parameters on the output of the device are analyzed. Current density is an important parameter for system performance. Increasing the current density leads to increased power produced by the system, decreased exergy efficiency in the system and increased energy efficiency. After-burner, air and fuel heat exchangers are observed to have the highest exergy destruction rates. Lower current density values are desirable for better exergy-based sustainability from the exergetic environmental impact assessment. Higher current density values have negative effect on the environment.

An integrated solar combined cycle system based on parabolic trough solar collector and combined cycle power plant is proposed. The advanced system is socio-economic significance compared to traditional combined cycle power system. Plainly, the exergetic analyses (exergy destruction and efficiency) via conventional and advanced methods are used for thermodynamic properties of the integrated solar combined cycle system components. In addition, the exergy destruction is divided into endogenous, exogenous, avoidable, and unavoidable. The results show that the combustion chamber has the largest fuel exergy and the highest endogenous exergy destruction rate of 1001.60 MW and 213.87 MW, respectively. Additionally, the combustion chamber has the highest exergy destruction rate of 235.60 MW(60.29%), followed by the parabolic trough solar collector of 54.20 MW(13.87%). For overall system, the endogenous exergy destruction rate of 320.83 MW (82.10%) and exogenous exergy destruction rate of 69.97 MW (17.90%) are resulted via the advanced exergy analysis method. Besides，Several methods to reduce the exergy destruction and improve the components’ efficiency are put forward.

This paper develops a four-step copper-chlorine cycle for hydrogen production with conceptual modification through flash vaporization and evaluates its economic and environmental performances through exergy approach. The flash vaporization method is employed as a new approach for realizing the anolyte separation under vacuum conditions for reducing the thermal requirement of the anolyte separation step and consequently of the overall cycle. A flash vaporization is usually employed commercially for seawater desalination purposes. However, its utilization in a thermochemical hydrogen production process has not been considered previously which is really one of primary novelties of this investigation. The obtained results for the exergoeconomic and exergoenvironmental analyses of the conceptually modified cycle are also compared with those of the existing integrated cycle at the Ontario Tech University. The exergoeconomic analysis of the cycle has also been carried out for the cycle operating with and without waste heat recovery. In this regard, waste heat recovery from a steel furnace has been considered for supplying the required thermal energy for the hydrolysis step. The cost assessment of the cycle is carried out in the Aspen-plus. Compared with the existing cycle, the cycle with the proposed modification results in a lower unit cost of hydrogen. Moreover, a significant reduction in the unit cost of hydrogen is observed when waste heat recovery is considered for the modified cycle. The average unit hydrogen cost for the modified version of the cycle is evaluated to be 4.7 $/kg which reduces to 2 $/kg with incorporation of waste heat recovery. Furthermore, the overall environmental impact of the existing cycle can be potentially minimized by considering the proposed modification through flash vaporization.

Publisher Summary This chapter presents an analysis of the efficiencies and inefficiencies of a system, which can be used to identify where the greatest opportunity for gains can be derived. It can also be used to benchmark the performance of one system against another. The thermal efficiency of any furnace system is defined as the useful energy derived from the system relative to the energy input. However, it is not necessary to measure the energy that is lost through the walls of the furnace, etc. to calculate the efficiency. It is only necessary to know the useful energy out, which is usually relatively easy to determine, as it will be directly related to the production rate. The efficiency of a furnace system depends on each step by which the energy is transferred from the chemical fuel energy and the electrical energy to the process energy contained in the end product. The total efficiency is dependent on the efficiency of each operation in the process, such as pump, preheater, furnace, and cooler. Examination of furnace performance data can help to usefully identify the relative contributions of thermal quantities. If the production rate is plotted against thermal input then, allowing for a reasonable degree of scatter owing to other influences, a straight line relationship is usually observed.

Large-scale thermal energy storage (TES) emerges as key for the expansion of renewables-based district heating (R-DH) as it is able to bridge the seasonal gap between the heating demand and the availability of renewable energy resources (e.g. solar energy). This work develops a framework for techno-economic analysis considering several key performance indicators (e.g. energy efficiency, exergy efficiency). As TES systems integrated in DH are typically stratified, the work also examines the TES by means of stratification number and efficiency. The economic feasibility of the TES options is examined via the TES specific investment cost. Then, the work recommends the levelized cost of stored heat (LCOS) as a practical measure for the TES techno-economic feasibility. The outcomes show that the tank has higher performance in terms of efficiency indicators (energy and exergy) and stratification measures, but it is characterized with high specific cost. Yet, the tank LCOS is lower compared to that of the shallow pit due to its low performance and despite its low specific cost. Thus, in order to take advantage of the tank's better performance and shallow pit's lower specific cost, the work proposes a third TES geometry called as hybrid TES that combines both tank and shallow pit. The results reveal the potential of this geometry as it arises as a promising option. Furthermore, the results indicate that the transition to low-temperature R-DH brings technical and economic advantages as the LCOS tends to be lower compared to that of TES installed in high-temperature R-DH. Moreover, the work reveals that due to the importance of increasing the economic feasibility for large-scale TES, it is of crucial to develop new materials and construction methods to ensure cost-efficient insulation of the buried TES.

Background Chemical looping combustion (CLC) has attracted wide interests with high-efficiency and near-zero energy penalty carbon capture. However, the low-pressure operation of the most adopted circulating fluidized-bed reactors restricts the application of the downstream combined (gas-steam turbines) cycle, leading to an unsatisfying system efficiency. For this reason, this paper integrates atmosphere CLC with the combined recompression supercritical CO2 Brayton cycle and organic Rankine cycle (CLC-sCO2-ORC) for power generation. Methods The proposed system was modeled and simulated with Aspen Plus to manifest its tech-economic feasibility. Significant findings The sensitive analysis suggests that the optimal sCO2 turbine inlet temperature and pressure are 700 °C and 280 bar, respectively, and the recompression split fraction is 0.72. Under the optimal condition, the energy efficiency of 51.79% is superior to the conventional natural gas combined cycle (NGCC) (49.38%) and other CLC-based power generation technology (50.13%). Exergy analysis was also performed to put forward some improvement strategies. Importantly, CLC operating temperature imposes nearly no impact on exergy loss. Besides, the economic indicator, levelized cost of electricity (LCOE) is supposed to be profitable at 79.17 $/MWh, which is lower than that of other CLC-based power generation system (83.12 $/MWh).

To develop a solution for clean gas supply and biomass utilization and indirect renewable power storage, this work proposes a novel SNG process integrating O2-enriched air gasification with O2 purity range of 80–96%. Low-cost vacuum pressure swing adsorption (VPSA) is integrated to produce O2 with purities of 80% and 90%; while cryogenic air separation (CAS) is applied for 96% O2 purity. Besides SNG, the syngas of the methanation product without CO2 separation (SG) is considered as a new type of safe fuel for rural areas. The technical and economic assessments are successively performed based on simulation data. The effects of important operating variables on technical performances are investigated to determine the optimal values. The overall energy and exergy efficiencies of SG reach 68.37% and 62.59%, respectively, while those of SNG achieve 65.69% and 60.38%, respectively. The equivalent unit product costs of SG and SNG are 1.661 ¥/Nm3 and 2.031 ¥/Nm3 at base scenario, respectively, which are quite profitable. The sensitivity analysis of the cost indicates that the products has strong cost competitiveness within the actual fluctuations, and the constraints for SG is much looser than that for SNG to gain profit. The process integrating VPSA has obvious advantages in efficiencies and unit production cost, which come with the price of visible disadvantages in CH4 concentration and higher heating value (HHV). The work is a representative reference for the countries lacking natural gas and valuable to guide the development of O2-enrich air gasifier, process optimization and indirect renewable power storage.

Nowadays due to increasing energy demand in the world, the use of energy systems with maximum efficiency is unavoidable. Thermal integration of the systems decreases the number of equipment employed and also raises the efficiency of the hybrid configuration. In the present study, an innovative hybrid system for cogeneration of power and desalinated water including organic Rankine unit, carbon dioxide power plant, Kalina power cycle based on the seawater temperature difference, and multi-effect desalination system is developed. Part of the heat required by the system is provided by solar flat plate collectors. The innovative hybrid system produces 849.5 MW power and 198.5 kg/s potable water. Exergy investigation of the system indicates that the most exergy destruction in the whole system belongs to the combustion chamber and heat exchangers, each of which is 46.60% and 34.91% of the total exergy destruction, respectively, which shows that more than 80% of exergy destruction is related to these two parts. The exergy efficiency of the whole system is 44.81%. Through the pinch method, the heat exchanger network related to the multi-stream heat exchangers of the hybrid system is extracted. The effect of air /fuel ratio (inlet to the combustion chamber) on system performance in the parametric analysis is examined. One of the main results is a 12.69% improvement compared to the initial state of total electrical efficiency of the structure in case of increasing the fuel input to the combustion chamber up to 62.00 kg/s. By system reliability analysis and examining different modes of failure and repair rates of different sections of the system, the probability of the structure operation in different cases is extracted.

The selection of suitable working fluid for simple and recuperative organic Rankine cycle (ORC) operating under subcritical, superheated and supercritical conditions are investigated. 11 fluids with critical temperature above 1500C are considered as potential candidates. Performance screening parameters such as net power output, thermal efficiency, turbine sizing parameter (SP) and volumetric flow ratio (VFR), exegetic parameters like irreversibility rate, fuel depletion ratio, and improvement potential rate of exergy destruction were also evaluated. Results indicate that R600a, R236fa and R1233dz(E) demonstrated the best performance for subcritical, superheated and supercritical simple ORC, respectively. R236fa and R1233dz(E) proved more suitable for subcritical/superheated and supercritical recuperative cycles, respectively. The system exegetic efficiency is reveal to be significantly higher in subcritical/superheated (61-65%) cycles compared to the supercritical (35-45%) cycle, the evaporator seen as the main source of exergy destruction, accounting for 17-37% of inlet exergy destroyed and about 8-24% in the turbine

The current work proposes and investigates a novel multigeneration system (power, hydrogen, and energy) comprising a flash-binary geothermal power plant, a modified Kalian cycle, a low-temperature electrolyzer, and a reverse osmosis desalination setup. Indeed, the whole system has been devised regarding the multi-heat recovery technique and smart management of products through a structural modification. To emphasize the ability of the newly designed system in this work, the data of the Sabalan geothermal plant in Iran has been used as a case study. Subsequently, the feasibility of the proposed multigeneration system has been examined by the modified specific exergy costing (M-SPECO) method, characterizing the exergetic and cost aspects of the system. The M-SPECO method is recognized as an energy level-based cost scrutiny technique to evaluate energy conversion systems. Accordingly, the sensitivity study through single and dual parametric analyses has been implemented, wherein separator 1 pressure was the main parameter. Likewise, the non-dominated sorting genetic algorithm-II (NSGA-II) method has been applied to optimize the calculations and reveal the optimum conditions and results. In this way, the achieved optimum exergy efficiency of the system was calculated as 47.25%, followed by a value of 7.66 $/GJ for the modified overall unit cost of products.

In this study, a basic organic Rankine cycle (ORC) is introduced in an air separation process for waste heat recovery. Conventional and advanced exergy analyses are adopted to investigate the thermodynamic properties of components in the ORC. A comprehensive thermodynamic model is constructed to improve the advanced exergy analysis in the ORC, thereby encompassing real, theoretical, unavoidable, and hybrid cycles. Nine organic working fluids are introduced to investigate the influence on the ORC performance. (1) The conventional exergy analysis reveals the following: (a) The expander constantly demonstrates the maximum exergy efficiency except when R227ea is used. (b) The evaporator constantly exhibits the maximum exergy destruction regardless of the working fluid used. (c) The maximum product exergy is obtained when R114 is used. (d) Key components must focus on the condenser and evaporator to improve the ORC performance. (2) The advanced exergy analysis reveals that the expander demonstrates maximum potential for improvement because its endogenous avoidable exergy destruction accounts for approximately 90% of its real exergy destruction for all working fluids. The expander must be improved to achieve the optimal ORC performance. The advanced exergy analysis can distinguish the source of exergy destruction and the magnitude for possible improvement via the proposed thermodynamic model in this study. The comprehensive thermodynamic model can promote the investigation of the advanced exergy analysis in the ORC. Applying conventional and advanced exergy analyses to investigate the thermodynamic performance of a system or its components is highly recommended.

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.

The solar energy produced by Scheffler parabola (10 m2) is not fully exploited by the solar distillation system of aromatic and medicinal plants. In this work, the optical losses in the primary and secondary reflectors, and the thermal losses at each part of this system (solar still, steam line, condenser) were determined. A thermal energetic and exergetic analysis were also performed for a solar distillation system of rosemary leaves. For average intensity radiation of 849.1W/m2 and 6 Kg of rosemary leaves during 4 h of distillation, exergy and optical efficiencies of the system achieved up to 26.62% and 50.97%, respectively. The thermal efficiency of the solar still, steam line, and condenser is about 94.80%, 94.30%, and 87.76%, respectively. The essential oil yield per unit of consumed energy and the total efficiency of the solar distillation system, taking into account the heat losses in the solar still, steam line, and condenser, as well as the optical losses in the two reflectors, is 6.18 mL/ kWh and 40.00%, respectively. The efficiency can be as high as 42.42 % if the steam line is insulated. Moreover, the comparison between the solar steam distillation and conventional steam distillation shows that solar distillation is much more efficient since it gives better results and especially it avoids the emission of 12.10 kg of CO2 during extraction.

In this paper, design and development of an energy-efficient oil-fired tilting furnace with an innovative recuperator are reported. During the melting of metals, it is reported that around 50% of the total energy is lost in flue gases. Therefore, there is always a need to improve upon the efficiency of the furnaces. The design of the recuperator is based upon the application of all the three basic modes of heat transfer to preheat the incoming air. Financial and environmental aspects were also evaluated after upgradation with the recuperator. The internal hollow pipe of the proposed recuperator is so designed that at its exterior cylindrical surface, multiple turns of a guide way are welded in a spiral fashion. This increases the heat transfer between the flue gas and ambient air to the burner. The study shows that the efficiency of the oil-fired tilting furnace got enhanced by 50% after implementing the proposed recuperator. Specific fuel consumption without the recuperator was 0.166 kg/kWh, which was reduced to 0.138 kg /kWh with the recuperator. The principle of increasing thermal efficiency and limiting fuel consumption was based on heat recovery from the combustion products to preheat the cold incoming fuel mixture. Therefore, this study focuses on the relations between combustion and heat exchanges on a large scale. The exergy evaluation technique was used constructively to estimate the furnace’s efficiency since the exergy efficiency is an additional sustainable appraisal in real situations. A channel for flue gases is provided in the developed furnace, which helps to divert hazardous gases away from the working environment.

This work discusses the supercritical technology that has been instrumental in reducing pollution levels and quick load response from the thermal plant. Various operating parameters such as main steam pressure and temperature; reheat steam pressure and temperature; excess air ratio for a given fuel, feedwater heater bleed steam pressure and temperature are listed. The influence of their optimization is analyzed to reduce the pollution levels to a certain extent. Primarily, this study deals with utilizing artificial intelligence with the existing plant to predict the optimum thermal plant performance. The input parameters that are used in the artificial neural network (ANN) are evaluated to find the energy input through a mixture of coal and air. The ANN algorithm computes different parameters that initiate the optimization, resulting in the least energy input to the plant, as an algorithm fitness function. The built model could also use online optimization in addition to optimizing the design parameters when further modifications are made. This model is used to determine the effect of various excess air ratios and different types of fuels on the performance of the plant. The different boiler losses of boiler from different coal samples and exergy and exergy losses were analyzed at a particular excess air ratio. Finally, this paper predicts that by using ANN tool optimization, around 30% of coal savings are achieved which is equivalent to CO2 pollution reduction, less reduction of NOx and SOx pollutions, and an increase in plant efficiency by 1.3%.

A new cleaner power generation system (IPGS) is proposed and investigated in this paper. Integrating combined cycle with supercritical water gasification of coal, the thermodynamic energy of the produced syngas is cascade utilized according to its temperature and pressure, both sensible and latent heat of the syngas can be recycled into the system, and thereby the net power efficiency can be about 6.4 percentage points higher than that of the traditional GE gasification based power plant (GEPP). The exergy analysis results show that the exergy efficiency of the proposed system reaches 52.45%, which is 13.94% higher than that of the GEPP, and the improvement in exergy efficiency of the proposed system mainly comes from the exergy destruction decline in the syngas energy recovery process, the condensation process and the syngas purification process. The syngas combustion process is the highest exergy destruction process with a value of 157.84 MW in the proposed system. Further performance improvement of the proposed system lies in the utilization process of syngas. Furthermore, system operation parameters have been examined on the coal mass fraction in the supercritical water gasifier (GF), the gasification temperature, and the gasification pressure. The parametric analysis shows that changes in coal concentration in the GF exert more influence on the exergy efficiency of the system compared with the other two parameters.

To enhance the performance of the thermodynamic systems, reduce the pollutants emission to the environment, and decline the fuel utilization, waste heat recovery methods are in high interest. In this paper, a new configuration of an integrated solid oxide fuel cell and gas turbine combined with a biogas reforming cycle is presented for the cogeneration of power and hydrogen. The thermal energy discharged from the SOFC-GT system is used to supply the energy required for the reforming reaction in the biogas reforming cycle for hydrogen production. Comprehensive thermodynamic and thermoeconomic modeling has been performed using EES software. Also, a parametric study has been performed to demonstrate the effect of different parameters on the main performance metrics of the devised system. The results revealed that the energy efficiency and exergy efficiency of the proposed combined system have increased compared to the SOFC-GT system by 23.31 % and 28.19 % , respectively. The net output power and hydrogen production rate are obtained by 2726 kW and 0.07453 kg / s , respectively. From the exergy viewpoint, the afterburner causes a considerable amount of exergy destruction for the system by approximately 26 % of the total exergy destruction rate. Besides, the sensitivity analysis revealed that by increasing the inlet temperature of the fuel cell, the cell voltage reaches a maximum value at a temperature of 679 K and then decreases. Moreover, the total exergy destruction rate and SUCP of the cogeneration system is calculated by 1532 kW and 9400 $ / GJ , respectively.

Two schemes of power and refrigeration cogeneration Kalina cycle with adjustable refrigeration temperature (PPRAT-KC) based on the efficient cogeneration cycle PPR-KC are proposed and studied. In the PPRAT-KC, the refrigerant vapor is absorbed in a pressure adjustment absorber with dilute solution either from the separator or the low-pressure pump, and by altering the flow rate of the dilute solution, the refrigeration temperature is able to be adjusted with nearly no effect on the amounts of energy outputs. The amount of net power or refrigeration capacity in the PPRAT-KC can be also adjusted by changing the flow rate of solutions fed to the power and refrigeration sub-cycles. Under temperatures of heat source and cooling water of 400℃ and 30℃, respectively, the change range of refrigeration temperature for the two schemes of the PPRAT-KC are about from -22℃ to 7.5℃, and the performances of the two schemes are similar. With the same work concentration of 0.5 and refrigeration temperature of -15℃, the effective exergy of PPRAT-KC is 0.5653, which is 4.145% and 10.97% higher than those of the PPR-KC and the triple pressure Kalina cycle, respectively.

The optimal equipment arrangement for a system for cogeneration of thermal and electrical energy for a total site is determined with exergoeconomic analysis. A steam power plant can operate concurrently in a dual-use mode producing steam and electricity. It is important to know the potential for cogeneration before designing and optimizing a central utility system in order to establish on site fuel demand targets. In the current study, two case studies with different backpressure steam turbines arrangement are considered and, if extra power generation is needed, designs with a system of condensing and gas turbines are examined. The minimum exergy destruction rate, maximum exergy efficiency, minimum total capital cost rate and minimum exergy destruction cost rate for these arrangements are investigated with exergoeconomic analysis. Finally, selected backpressure steam turbines arrangement in conjunction with the gas turbine system are introduced for finding the optimum arrangement of the cogeneration system in the total site with an exergoeconomic approach.

This study aims to present a novel tri-generation plant consisting of a molten carbonate fuel cell (MCFC) unit coupled with a Stirling engine (SE), a heat recovery steam generator (HRSG), and two types of absorption refrigeration cycles (ARCs), i.e., Generator Absorber eXchanger (GAX) and Vapour Absorption Refrigeration (VAR). The proposed system is evaluated from energy, exergy, as well as environmental impact (3E) points of view. To carry out the parametric study, three sub-models are also introduced for the whole system. The sub-model (1) investigates the solo MCFC with the new configuration. In the sub-model (2), the SE and HRSG are added to boost the power generation and overall system efficiency through employing the heat wasted in the sub-model (1). In the last sub-model, for cooling purposes, the surplus heat of MCFC is reutilized using an absorption refrigeration cycle. Besides, to make a comparative study between GAX and VAR systems, the sub-model (3) is classified into two different schemes: (a) with a VAR cycle, and (b) with a GAX cycle. The results reveal that the exergy efficiency and CO2 emissions of the sub-models (1), (2), and (3) are 48.04%, 51.24%, 52.35% (VAR cycle), 52.12% (GAX cycle), 0.388 t/MWh, 0.364 t/MWh, 0.357 t/MWh (VAR cycle), and 0.358 t/MWh (GAX cycle), respectively. Either with GAX or VAR cycle, the proposed system indicates an acceptable standard of functionality in thermodynamic and environmental perspectives.

The concern for environmental devastation due to high dependency on fossil fuel sources is shifting focus towards efficient utilization of energy by integrating renewable energy and integrated energy system. Efficient energy deployment can be attained by alleviating the actual losses, costs and environmental impact of the energy sources. This paper aims to address the above issues by reviewing the 4E analysis known as energy, exergy, exergoeconomic and exergoenvironment analysis of thermal power plants, intermittent renewable energy and integrated energy system. Amongst other noteworthy aspects outlined in this paper, it has been found out that extensive work has been done on TPP energy and exergy analysis but exergoeconomic and exergoenvironment analysis are still considered as emerging fields. Moreover, most of the analysis conducted for intermittent renewable energy and integrated energy system is based on energy analysis. Some vital conclusions have been drawn from literature survey like boiler, PV surface module and wind rotor are the major sources of exergy destruction/losses in thermal power plants and intermittent renewable energy system. Decreasing the above components losses will significantly increase the energy quality, thereby will achieve a cost-efficient, sustainable and eco-friendly energy system.

Series and parallel two-stage evaporative strategy for vapor compression refrigeration cycles characterized by temperature and humidity independent control were presented. The theoretical model was established to analyze the performance of parallel two-stage evaporative strategy regarding the coefficient of performance (COP), exergy loss, exergy efficiency in comparisons with series system. And refrigerants R290 and R600 with low global warming potential (GWP) and no ozone depletion potential (ODP) are proposed as alternative refrigerants for R134a in two systems. The results show that compared with R134a, the proposed R600 has better performance with higher specific refrigerating capacity and coefficient of performance, of which specific refrigerating capacity increase 102.72% than that of R134a on average. Series two-stage evaporative strategy for vapor compression refrigeration cycle with R600 had the optimal techno-economic performance, which COP and exergy efficiency are 7.8% and 11% higher than that of parallel two-stage evaporative strategy, respectively.

Solar energy based power generation systems can reduce pollutants emissions by reducing fossil fuel consumption. A new option for this idea is the Organic Rankine cycle coupled with a concentrating solar collector. The present study provides the Organic Rankine cycle performance using energy, exergy and economic approaches, selecting the appropriate operating fluid for the cycle consisting of Organic Rankine cycle and Linear Fresnel solar reflector. The effect of different organic fluid as well as different nanofluids on the overall performance of the cycle is investigated. Sensitivity analysis is discussed to evaluate the effect of various factors such as solar radiation, inlet temperature of solar system, mass flow rate, and inlet temperature and pressure of turbine on energy system performance. It was found that, the results provided in the present study do not correspond to any of the findings of previous similar studies. In addition, about 170 collectors of Linear Fresnel reflectors are needed to supply the thermal power required by the Organic Rankine cycle system. Under design conditions, the Levelized Cost of Energy and Simple payback time for the proposed hybrid system are obtained 0.0446 Euro/kWh and 7.74 years, respectively. Furthermore, the investment cost of the Linear Fresnel reflector system plays a key role in the economic justification of the proposed hybrid energy system.

In this investigation, a solar-driven multi-generation plant is developed and studied through exergy assessment. The developed integrated system is designed to provide power, cooling, freshwater, and hot water for an industrial complex. The designed layout consists of solar parabolic trough collectors as the main driver which can provide the driving temperature of 220 °C at its maximum output, a combination of Kalina cycle and ejector refrigeration to produce cooling load and power for the industrial complex, and multi-effect distillation unit to generate freshwater. Exergy assessment shows that collectors are the most destructive equipment in the designed layout. The exergy efficiency of the solar parabolic trough collectors reaches to 49.36%. The total exergy efficiency of the presented system achieves up to 25.92%. The designed system provides 32.27 kW of power, 156.3 kW of cooling, 4.907 m3/h of freshwater, and 1.449 m3/h of hot water at 61.4 °C. Additional assessments show that vapor generator pressure is a key factor on the output performance of the presented system. It has been shown that the total exergy efficiency of the system decreases by increasing the vapor generator pressure. The economic assessment illustrates that the investment return period and the prime cost of the product are 3.958 years and 1.773 US$/m3 freshwater, respectively.

The composite energy pipeline (CEP) is an emerging multi-energy flow transmission technology that combines superconducting cable and liquefied natural gas (LNG) pipeline. The CEP carries a large amount of high-grade cold energy during operation. However, the existing regional integrated energy system(RIES) does not have a corresponding recycling plan for the input cold energy. We propose a new type of energy system coupled by a CEP and RIES, which is based on the research of the current situation of the cold, heat, electricity and gas supply modes of the RIES. On this basis, in order to make full use of the cold energy carried by the CEP, this paper also proposes a cold energy recovery method combined with the RIES, and the cold energy cascade utilization based on exergy analysis method. We improve the energy efficiency of the system through cold recovery and the unified optimized dispatch of the cold, heat, electricity and gas supply systems, finally realize the efficient use of energy by the system and improve the profitability of the system.

The optimum size of the prime mover (PM) for combined cooling, heating and power (CCHP) systems is determined taking account of economics, environmental impacts, energy, and exergy. The optimum size of the PM greatly increases the justification of establishing a CCHP system. Optimum sizing of the PM is conducted here considering exergy efficiency, exergy destruction rate, total energy efficiency, overall fuel energy consumption, carbon release, carbon release decrease, equivalent uniform annual benefit, and payback duration. To determine the optimum size, an objective function is presented in which some of the aforementioned criteria are minimized and some others are maximized. To solve the problem arisen from this objective function, the improved pathfinder optimization algorithm is proposed. To prove its superior performance, it is compared to six other popular optimization algorithms used in CCHP optimization using six benchmark functions. After obtaining the optimum size of the PM, sensitivity analyses are conducted on all of the eight assessment sub-criteria versus the PM capacity, and the results are given in figures. In addition, their values are given with the optimum size of the PM. The results indicate that the studied CCHP with the optimum PM size yields exergy efficiency of 55.53%, exergy destruction rate of 48.34%, total energy efficiency of 68.79%, and overall fuel energy consumption of 209 kWh. Also, this system will produce 36.82kg of carbon per hour which is 23.46% lower than the initial separated generation system. Moreover, with the equivalent uniform annual benefit of 26376$, it will pay back in 3.21 years.