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• Wet and dry cooling for three direct oxy-fuel sCO 2 power cycles are compared. • Energy, exergy, economic and multi-objective optimization analyses are conducted. • The preheater integration improves the efficiency by 13.27% (wet), and 6.58% (dry) • The overall efficiency of the wet cycle (72.04%) is higher than the dry (70.55%) • The LCOE of the improved cycle is lower by 19.1% (wet), and 11.4% (dry) • A minimum LCOE of 4.67¢/kWh e is obtained for wet and 6.14¢/kWh e for dry cycles. Oxy-combustion supercritical CO 2 power cycles have the advantages of high-energy efficiency and near-zero pollutant emissions. Thus, these cycles are considered as an efficient way to reduce CO 2 emissions while maintaining economic growth. The major drawbacks of this technology include the lack of validated levelized cost of electricity (LCOE) studies; lower turbine inlet temperatures studies to accommodate the integration of various energy sources; solutions for the thermodynamic imbalance of the regenerator; and investigating the dry- versus the wet-cooling methods. These drawbacks are addressed in this paper by presenting comprehensive thermoeconomic and optimization analyses for three direct oxy-fuel sCO 2 power cycles in wet and dry-cooling conditions. The first cycle M1 is a direct oxy-fuel sCO 2 power cycle without preheater, the second cycle M2 integrates a preheater in parallel with the low-temperature recuperator of M1 while the third cycle M3 integrates a preheater in parallel with the high and low-temperature recuperators of M1. Results show that the integration of the preheater improves the thermal efficiency of M2 by 5.81% (wet), and 3.27% (dry), and of M3 by 13.27% (wet), and 6.58% (dry). The LCOE of M1 (without preheater) is higher than that of M2 by 10.8% (wet), and 5.7% (dry), and of M3 by 19.1% (wet), and 11.4% (dry). A minimum LCOE of 4.667¢/kWh e is obtained for M3 (wet) and of 6.139¢/kWh e for M3 (dry). At higher waste heat source temperature of 700 °C, the overall efficiency is improved by an average of 11% and the LCOE is reduced by 1.43 ¢/kWh e. [ABSTRACT FROM AUTHOR]

Applications of dual-evaporator refrigeration systems have recently gained much attention both in academia and industry due to their multiple benefits. In this study, a comprehensive thermodynamic and economic analysis is conducted to evaluate the potential of using several environmentally friendly refrigerant couples and identifies the most suitable one yielding the best economic results. To achieve this goal, a detailed parametric study is conducted, and an optimization process is performed using a particle swarm optimization (PSO) approach to minimize the unit production cost of cooling (UPCC) of the cascade refrigeration system. The results showed that among all selected 18 refrigerant pairs and for all ranges of examined operating parameters, the R170-R161 pair and R1150-R1234yf pair are identified as the best and worst pairs, respectively, from both thermodynamic and economic viewpoints. The results also confirm that R170-R161 pair has an improvement over R717-R744, used as a typical refrigerant pair of cascade refrigeration cycles. For a base case analysis, the COP of R170-R161 and R1150-R1234yf pairs is determined as 1.727 and 1.552, respectively, while their UPCC is found to be $0.395/ton-hr and $0.419/ton-hr, respectively, showing the influence of proper selection of refrigerant pairs on the cascade cycle's performance. Overall, this study offers a useful thermodynamic and economic insight regarding the selection of proper refrigerant pairs for a dual-evaporator cascade vapor compression refrigeration system. [ABSTRACT FROM AUTHOR]

• An enhanced ammonia-water CCP is introduced and analyzed thermoeconmically. • Dual level cooling temperature is achieved by utilizing an ejector. • Optimized energy and exergy efficiencies are obtained 68.8 % and 37 %, respectively. • The simple payback period is approximately 4.8 years. The present study proposed and investigated a novel parallel combined cooling and power (CCP) system using the ammonia–water solution as a working fluid. The major advantage of this system is employing two evaporators to produce cooling in dual level cooling temperatures and capacities. To produce high-temperature refrigeration output, an ejector refrigeration loop is introduced. Moreover, the power generation subsystem is employed between absorber and rectifier to recover of ammonia content in the vapor exiting the turbine for refrigeration. To prediction of ejector performance, a new model is proposed based on the shock circle model. To find the effect of key parameters on the system performance, the system is analyzed thermo-economically. The parametric study results show that high-temperature cooling load has the biggest effect on both thermodynamic and economic performance. Moreover, a parametric optimization is conducted and the optimized system is compared with several ammonia-water CCP systems in the literature. The comparison results show a significant enhancement in thermodynamic performance. In this case, the optimal energy efficiency of 68.8 %, exergy efficiency of 37 % and cooling-to-power ratio of 8.77 are estimated. From economic analysis, the optimal net present value and simple payback period are obtained by 49.2 M$ and 4.8 years, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new climatic zone map of Turkey is proposed. • Classification is based on OIT via FCM algorithm. • OIT is calculated for different wall, insulation material and fuel types. • One fifth of cities have been shifted to a new zone. • Effect of reclassification on savings in energy, cost and GWP is presented. Classification of climatic zones is required for building thermal regulation. In this context, a novel approach based on thermoeconomic analysis is proposed to reclassify climatic zones of Turkey. The classification is carried out by accounting different climatic-built parameters, namely thermal insulation, main wall component, fuel type, as well as heating and cooling degree-days (HDD and CDD). With this aim, 80 provinces of Turkey are reclassified into 5 zones based on fuzzy c-means clustering method regarding 27 different optimum insulation thickness attributes calculated for each city. The results showed that compared to the current national thermal zones, based only on HDD values, 16 out of 80 provinces shift to a new category, all of which correspond to a higher zone indicating the requirement of a thicker insulation layer. The results are presented with membership degrees giving more insight into the climate of analysed cities, discussed in terms of reduction in energy-cost and global greenhouse gas emissions. The obtained new classification revealed that the current national thermal zoning methodology is inadequate in division of the studied geographical area particularly for mild climates where cooling needs are significant. Finally, an updated climate zone map of Turkey for building thermal regulation is proposed. [ABSTRACT FROM AUTHOR]

Organic Rankine Cycle (ORC) is an effective way to recycle waste heat sources of a marine diesel engine. The aim of the present paper is to analyze and optimize the thermoeconomic performance of a Series Heat Exchangers ORC (SHEORC) for recovering energy from jacket water, scavenge air, and exhaust gas. The three sources are combined into three groups of jacket water (JW)→exhaust gas (EG), scavenge air (SA)→exhaust gas, and jacket water→scavenge air→exhaust gas. The influence of fluid mass flow rate, evaporation pressure, and heat source recovery proportion on the thermal performance and economic performance of SHEORC was studied. A single-objective optimization with power output as the objective and multi-objective optimization with exergy efficiency and levelized cost of energy (LCOE) as the objectives are carried out. The analysis results show that in jacket water→exhaust gas and jacket water→scavenge air→exhaust gas source combination, there is an optimal heat recovery proportion through which the SHEORC could obtain the best performance. The optimization results showed that R245ca has the best performance in thermoeconomic performance in all three source combinations. With scavenge air→exhaust, the power output, exergy efficiency, and LCOE are 354.19 kW, 59.02%, and 0.1150 $/kWh, respectively. Integrating the jacket water into the SA→EG group would not increase the power output, but would decrease the LCOE. [ABSTRACT FROM AUTHOR]

Two novel trigeneration cycles are proposed based on Absorption Heat Transformers (AHTs) to generate power and produce freshwater, and heating effect from low-temperature geothermal energy. Simulation models are developed to examine the thermodynamic and thermoeconomic performances of the systems based on the single-stage, double and double-effect AHTs. The power is generated in an Organic Rankine Cycle (ORC) and a single-stage evaporation desalination system is employed to produce freshwater. The exergy performance parameters are determined, and the levelized cost of energy (LCOE) and water (LCOW) are considered as the criteria for the thermoeconomic assessment. According to the results, a maximum of 191.1 kW of power can be generated by the proposed systems, for a geofluid with a temperature of 95 °C and mass flow rate of 50 kg/s, that belongs to the double-effect AHT based system. This is 18.6 and 60.9 kW more than the single-stage and double AHT based systems power, respectively. Also, the energy and exergy efficiencies, as well as LCOE and LCOW for this system, are calculated to be 40.07%, 57.38%, 0.04636 $/kWh, and 34.85 $/m3, respectively. Moreover, a parametric study revealed the notable influences of temperatures of AHT components on the performance parameters of the systems. • Two novel trigeneration systems are proposed based on absorption heat transformers. • The proposed systems generate power, freshwater, and heating effect. • Thermodynamic and thermoeconomic performances of the systems are examined. • Energy and exergy efficiencies are 40.07% and 57.38% for double-effect based cycle. • The lowest levelized cost of water belongs to the single-stage based system. [ABSTRACT FROM AUTHOR]

The depletion of fossil fuel reserves and deterioration of ecological environment have brought unprecedented challenges to marine manufacturers under the prevailing global trade. To alleviate the severe situation and comply with the concept of energy-conservation and emission-reduction, the development of green, efficient and sustainable waste heat recovery technology is imperative. Here, we propose an advanced waste heat harvesting strategy considering two-phase flow simulation and energy deployment for marine dual-fuel engine. Significantly, the mechanism of bubble formation and its effect on the system are discussed. Subsequently, the relationships between the working-fluid and sensitivity parameters to the subsystem performance are analyzed. Interestingly, a parallel system is designed to dynamically control and deploy energy in coping with the marine real-time energy demand. After the multi-objective optimization, the thermodynamic, economic and environmental performance of the multistage system are calculated. The results prove that (i) the multistage system can recover the investment cost in 10.71 years, the output-power, cooling-capacity and fresh-water are 278.87 kW, 28.96 kW and 0.24 kg/s, respectively; (ii) compared with the original engine system, the output-power and thermal-efficiency of the engine-multistage system are increased by 287.6 kW and 6.89%, showing excellent thermodynamic performance. [Display omitted] • An advanced waste heat harvesting strategy for marine dual-fuel engine is proposed. • The influence of bubbles in two-phase flow on system performance is considered. • Parallel system is designed to deal with the real-time energy demand in the marine. • The optimal thermoeconomic conditions are determined by multi-objective optimization. • The output power, thermal and exergy efficiencies reach 287.6 kW, 30.2% and 63.3%. [ABSTRACT FROM AUTHOR]

In this paper, district heating (DH) potentials of the wastewater treatment plants (WWTPs) based on their biogas, electricity, and heat productions are considered. Two district heating scenarios are developed: (i) DH Scenario I which is based on both excess biogas storage of the WWTP and exhaust gas of the cogeneration with the actual power output, (ii) DH Scenario II which is based on the exhaust gas of the cogeneration with the increased power output using all the biogas produced. In DH Scenario I, it is found that 458 dwellings can be heated via the DH system proposed considering only the waste heat of the cogeneration. In addition, the natural gas consumption of 1112 dwellings with the same annual heating load can also be met using the purified biogas. In DH Scenario II, the electricity production could be increased to 1643 kWh by burning all the biogas produced in the cogeneration plant. In this scenario, the annual heating load of 755 dwellings in Gaziantep province can be covered using the waste heat in the DH system. The payback period for the DH Scenario I is calculated as 2.5 years, while for the DH Scenario II, it is obtained as 2 years. • DH and electricity production potentials of the WWTPs are considered. • Two DH and electricity production scenarios are developed. • Heat demand of 458 dwellings can be met with DH system developed in Scenario I. • Heat demand of 755 dwellings can be met with DH system developed in Scenario II. • Electricity production can be increased to 1643 kW with Scenario II. [ABSTRACT FROM AUTHOR]

[Display omitted] • A multigeneration system fueled by a geothermal source is proposed. • Absorption heat transformer and chiller have the highest irreversibilities. • The overall system performance in winter is better than that of summer. • The system has considerably high heating, cooling, and freshwater capacities. • Thermoeconomic indexes are significantly lower compared to similar systems. Population growth, economic challenges, and the environmental crisis force scientists and designers to pay more attention to clean, sustainable, and renewable-based energy systems. In this regard, due to the unlimited geothermal potential in many countries, the geothermal energy resource can be an economical alternative. Therefore, in the present work, a novel multi-generation system, based on a 100% geothermal resource, for power, cooling, heating, and desalination has been designed and analyzed, thoroughly. The system is evaluated from the energy, exergy, and thermo-economic viewpoints, and providing high heating/cooling potentials while reducing the thermoeconomic indexes is the major achievement of this study. The results demonstrate that the system's net power output, freshwater production rate, heating, and cooling capacities are 78.47 kW , 92.1 m 3 / d a y , 6251 kW , and 4991 kW , respectively. Moreover, the highest amount of exergy destruction occurs in the absorption heat transformer (42%) and the absorption chiller (35%), respectively. In addition, the chiller's absorber has the highest cost rate of exergy destruction, and the turbine and the evaporator of the organic Rankine cycle have the highest investment costs. It is found that energy and exergy efficiencies are 60.55% and 17.05%, respectively for summer, and 70.58% and 43.59%, respectively for winter, and the system's total cost rate is 44.12 $ / h with the payback period of 5.63 years. Furthermore, the parametric study shows that increasing the ambient temperature and decreasing the terminal temperature difference of the heat transformer's evaporator lead to higher exergy efficiency and lower total system cost rate. [ABSTRACT FROM AUTHOR]

Waste heat recovery in a gas turbine cycle for thermal desalination units is a convenient solution to reduce GHG emissions. In this study, multi-effect thermal vapor compression desalination (MED-TVC) and reverse osmosis (RO) plants are integrated with a gas turbine cycle through a recovery steam generator (HRSG) to reuse waste heat. The Thermodynamic, exergy, and thermoeconomic model of each section are developed. Besides, based on the interconnection between input and output streams of MED-TVC + RO, six configurations are proposed. The corresponding results are optimized via the Genetic Algorithm (GA) and compared through two different approaches. The total products in each approach are limited to 105,000, 122,500, and 140,000 m3/day. In the first approach, the MED-TVC plant production is constant (70,000 m3/day). In the second approach, MED-TVC desalination production is assumed to be variable to provide a large portion of total fresh water. The best configuration among six configurations in terms of the lowest production cost at both approaches is related to use the cooling water of MED-TVC as the RO system feed water. Moreover, the results showed that NO x , SO 3 , SO 2 , and CO 2 decreased to 165.53, 7.33, 783 ppm, and 10.5% of the volume fraction, respectively, by applying GHG analysis. • Reducing the cost of production of hybrid desalination plants is considered. • Based on the interconnection between MED-TVC and RO, six configurations are proposed. • The output stream of one plant (MED-TVC or RO) is used as another plant's feed water. • The optimal solution of each configuration is presented in two different approaches. • Thermodynamic, thermoeconomic, exergy, and GHG analyses are applied. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel geothermal systems are proposed for combined cooling and power generation. • Parametric and multi-objective thermoeconomic optimization comparisons are performed. • System Conf. (a) has the best power/exergy efficiency (58%) and specific cost (30 $/GJ). • Conf. (b) has the highest cooling/thermal efficiency (43%) and cost (67 $/GJ). • The cost rates of optimised Conf. (a)-(c) are 440, 560, 600 $/h for a given heat source. Comparative parametric and multi-objective optimization analyses of three novel geothermal systems are performed for combined cooling and power generation. The first (Configuration (a)) consists of an absorption power cycle and an ejector refrigeration cycle, the second (Configuration (b)) of a modified Kalina cycle and an absorption refrigeration cycle, and the third (Configuration (c)) of a double-flash power cycle and an ejector refrigeration cycle, in all cases for power generation and cooling, respectively. Both thermodynamic (energy, exergy) and economic criteria are compared to gain an understanding of the characteristics and performance of these systems, and to ascertain the most appropriate system for different scenarios. Results from the parametric study show that Configuration (a) has the highest power output and exergy efficiency, but lowest cooling capacity and overall (power plus cooling) thermal efficiency, while Configuration (b) has the highest cooling capacity and thermal efficiency, but lowest power output and exergy efficiency. From an exergoeconomic perspective, Configuration (a) has the lowest and Configuration (b) the highest total specific cost. Configuration (c) maintains, generally, a thermoeconomic performance in-between those of the other two systems. The optimization results indicate that if the thermal efficiency and total specific cost are considered competing objectives over a range of well conditions, the optimal solutions obtained by the LINMAP method for Configurations (a) to (c) have thermal efficiencies of 19.1%, 43.0%, 42.4%, exergy efficiencies of 57.6%, 23.6%, 33.1%, total cost rates of 436 $/h, 558 $/h, 596 $/h, and total specific costs of 29.7 $/GJ, 66.9 $/GJ, 43.5 $/GJ. If the exergy efficiency and total cost rate are considered competing objectives, the corresponding values are 13.0%/29.1%/10.5%, 67.3%/30.5%/37.3%, 362/353/384 $/h, and 24.9/67.5/42.7$/GJ, respectively. [ABSTRACT FROM AUTHOR]

• Thermo-economic model of binary flashing cycle for enhanced geothermal system is established. • The thermal efficiency, net power output, total investment cost and levelized energy cost are evaluation index. • Thermo-economic analysis is conducted considering both geothermal well and system operating parameters. • Recommended geothermal well depth and geothermal brine flow rate are given. • Optimum generation temperature, dryness and flashing temperature exist resulting in economic performance optimal. In this paper, as a promising technology, the binary flashing cycle (BFC) is proposed for enhanced geothermal systems (EGS) exploitation. The detailed thermo-economic model is developed. With the thermal efficiency, net power output, total investment cost and levelized energy cost (LEC) as evaluation criteria, the flowsheet modeling and thermo-economic analysis are conducted. It is revealed that larger geothermal well depth and geothermal brine flow rate are in favor for improving system thermal performance. However, it is not always beneficial for the economic performance. There exist the optimal depth (3300 m) and geothermal brine flow rate (57 kg/s), at which the LEC obtains the minimum (0.329 USD/kWh) and (0.328 USD/kWh), respectively. For an economic EGS operation, the geothermal brine flow rate should be no less than 50 kg/s. The influences of operating parameters, including generation temperature, dryness degree at the vapor generator outlet and flashing temperature, on the evaluation criteria are also discussed. To achieve better economic benefits, the generation temperature should be less than 110 °C and the dryness should be larger than 0.2. With the flashing temperature 72−82 °C, the EGS-BFC yields excellent thermodynamic and economic performance. The present investigation will be helpful for the geothermal well construction, resource mining and generation system operating parameters design. [ABSTRACT FROM AUTHOR]

The regional micro energy system (RMES) can meet users' multi-energy demand and realize the accommodation of renewable energy, which makes it a very promising energy utilization scheme. This paper presents a novel RMES structure with compressed air energy storage system (CAES) as the core energy storage component. Additionally, a bi-level optimal dispatching strategy for realizing the balance between supply and demand in regional micro energy system with compressed air energy storage system is proposed for the new scheme. The upper layer optimization calculates the optimal initial value of energy state of CAES in each energy supply cycle, and the lower layer optimizes the hourly operation strategy based on the thermoeconomic characteristics. An improved thermoeconomics method was introduced to reduce the dimensionality of the optimization model and increase the computational efficiency. The addition of parallel computing methods further accelerates the model calculation speed. Case studies demonstrate the effectiveness of the method. The proposed dispatching strategy based on thermoeconomics provides theoretical support for the application of CAES in multi-energy utilization scenarios, and provides a reference for the calculation of the revenue and payback period of the RMES. • A regional micro-energy system with compressed air energy storage is proposed. • Thermoeconomic characteristics of compressed air energy storage are analyzed. • A bi-level optimal dispatching strategy is proposed for the new scheme. • The optimal initial value of energy state in each energy supply cycle is calculated. • The improved thermoeconomics and parallel computing are used to speed optimization. [ABSTRACT FROM AUTHOR]

• A transcritical CO 2 based combined heating and power system is proposed. • Thermoeconomic analysis and multi-objective optimization are conducted. • Exergy efficiency is raised with lower turbine outlet pressure. • Optimized thermal efficiency is 122.88% with product unit cost of 23.53 $/GJ. The combined heating and power technology is an encouraging measure to ameliorate energy utilization efficiency and meet the ever-growing heating and power demands in buildings. Meanwhile, transcritical CO 2 cycles have been demonstrated to be powerful and ambitious competitors for exploitation of low-grade heat sources. In this paper, a novel geothermal driven cogeneration system is conceptually designed by coupling an ejector-expansion compression heat pump cycle into a transcritical CO 2 Rankine cycle. The system can simultaneously supply power, hot water and hot air. The mathematical model is built from the thermodynamic and economic perspectives under reasonable assumptions. Parametric study is first performed to assess relationships between key physical parameters and system performance. Results indicate that turbine inlet pressure is optimized in research scope for the greatest exergy efficiency. Decreasing turbine outlet pressure and increasing evaporation temperature can raise exergy efficiency but induce negligible influence on thermal efficiency. The optimal turbine outlet pressure and evaporation temperature exist to cause the lowest total product unit cost. Finally, the Non-dominated Sorting Genetic Algorithms-II is employed to execute multi-objective optimization with targeting to maximize system efficiencies and minimize total product unit cost. In the final optimal operating condition, the optimization results suggest 122.88%, 37.17% and 23.53 $/GJ for thermal efficiency, exergy efficiency and total product unit cost, respectively. [ABSTRACT FROM AUTHOR]

• A new dual-loop organic Rankine- Generator Absorber Exchange cycle proposed. • Performance of the system is analyzed from the viewpoints of energy and exergy. • An exergy efficiency of 78.75% is achievable for the hybrid system. • The highest irreversibility occurs in Turbine 1. This study aims to produce power and cooling by applying exhaust heat. To this end, a hybrid dual-loop organic Rankine – Generator absorber exchange cycle is designed and studied. Furthermore, a thermoeconomic analysis is an essential requirement to study the performance of a thermal cycle. For this reason, the thermoeconomic analysis of this cycle is performed. The dual-loop organic Rankine cycle used in the present study has one low-temperature loop and one high-temperature loop in which R143a and Water are used as working fluids, respectively. Also, in the generator absorber exchange refrigeration loop, ammonia-water is applied as a working fluid. In this research, the impact of pressure and temperature of the first evaporator as well as the generator temperature on exergy efficiency, thermal efficiency, total exergy destruction, exergy destruction ratio, net output power, the heat transfer rate of all components, and the coefficient of performance of the Generator absorber exchange section of the hybrid cycle are evaluated. The results indicate that with increasing the temperature of the first evaporator from 620 K to 680 K, the quantities of exergy efficiency, thermal efficiency, total exergy destruction, and net output power increases with the highest increase being 19.96%, 26.54%, 5.67%, and 32%, respectively. The highest exergy destruction ratio happens in the first turbine at the temperature of the first evaporator equal to 620 K, and the pressure of the first evaporator equal to 9 MPa. With increasing the temperature of the generator from 423 K to 448 K, for the generator absorber exchange refrigeration section of the hybrid dual-loop organic Rankine – Generator absorber exchange refrigeration cycle, the coefficient of performance increases by 3.69%. For the system, the exergoeconomic factor indicates that 13.39% cost of the system is relevant to the investment costs and the remaining is related to the cost of exergy destruction. [ABSTRACT FROM AUTHOR]

• Flexible heat integration improves solar efficiency during off design irradiance. • Dynamic optimization leverages flexible operation to maximize solar efficiency. • Performance of optimized hybrid operation outpaces standalone solar power plant. • Optimized flexible hybrid operation increases yearly solar efficiency by 23.3% • Optimized flexible hybrid operation reduces levelized cost of electricity by 54% Hybridization of concentrated solar power (CSP) plants provides flexibility in operation that can drastically improve the solar-to-electric (STE) efficiency and levelized cost of electricity (LCOE) relative to standalone CSP plants. Flexible heat integration (FHI) is a novel concept where the collection and integration of CSP within a power plant is modified relative to the amount of solar energy available. FHI improves the thermal efficiency of a hybrid solar tower steam Rankine cycle power plant but leads to increased pumping needs due to continuously elevated molten salt flow rates through the collection system, which can negatively impact STE efficiency. The present work is carried out to maximize the STE efficiency of a hybrid CSP plant utilizing FHI by employing a dynamic optimization framework where a genetic algorithm optimizes the operation of the plant over a given solar irradiance profile. The study concerns a plant hypothetically located in Salt Lake City, Utah. The optimization results confirm the accuracy of a predictive heuristic where the preferred operation of the plant can be estimated relative to local peaks in the incident power generated by the heliostat collection field. The optimized FHI operation demonstrates a yearly STE efficiency of 13.8%, whereas the equivalent base-level hybrid and solar-only plants exhibit solar efficiencies of 13.4% and 11.2%, respectively. Economic analysis shows that FHI reduces yearly natural gas costs, leading to a $0.5/MWh reduction in LCOE relative to the base-level hybrid configuration. Overall, the results show that hybrid FHI schemes exhibit economic benefits along with observed thermodynamic improvements. [ABSTRACT FROM AUTHOR]

• Energy and exergy efficiencies of diesel were higher than those of MAB fuel. • Exergy destruction had its max value (82.57 kW) at the amb temp of 35 °C. • Entropy production rate ranged from 0.262 to 0.266 kW/K for MAB. • Exergoeconomic parameter for MAB is less than that of diesel for all cases. • Microalgae biodiesel could be a remarkable alternative to diesel fuel. The usage of biodiesel fuel is significantly increasing all over the world since fossil fuel reserves deplete day by day. In this study, diesel fuel and microalgae biodiesel (MAB) fuels were preferred for energy and exergy analyses of IC engine and the effect of the ambient (dead state) temperature was investigated. Five different temperatures (0 °C, 5 °C, 15 °C, 25 °C and 35 °C) were selected as dead state temperature for the engine performance test. For both diesel fuel and MAB fuel, the results of energy and exergy analyses of IC engine were evaluated and advantages and disadvantages of the fuels were revealed. Furthermore, thermoeconomic and exergoeconomic analyses were conducted for diesel and microalgae biodiesel. The results showed that the performance of MAB fuel showed similarity with diesel fuel. The energetic and exergetic efficiencies for the engine using diesel fuel were slightly higher than those of the engine using MAB fuel. With increasing the ambient temperature, the destruction exergy rate increased while both heat transfer exergy rate and exhaust exergy rate decreased. In addition, the thermoeconomic parameter ranged from 0.00056 to 0.00064 kW/$ as the exergoeconomic parameter changed from 0.00083 to 0.00088 kW/$ for the engine with diesel fuel usage. The usage of MAB fuel was better than the usage of diesel fuel for both thermoeconomic and exergoeconomic aspects. [ABSTRACT FROM AUTHOR]

• A novel triple power cycle is proposed and evaluated using thermoeconomic analysis. • A gas turbine cycle is combined with an s-CO 2 recompression cycle and ORC. • The triple cycle is optimized using a particle swarm optimization algorithm. • The optimum efficiency and LCOE are 0.521 and $52.819/MWh, respectively. • The proposed cycle has superiority over a very efficient cycle from the literature. In this study, a novel triple power cycle is proposed where waste heat from a gas turbine cycle is utilized to drive a supercritical carbon dioxide (s-CO 2) recompression cycle and a recuperative organic Rankine cycle (ORC) in sequence. A detailed thermoeconomic model is developed and implemented in MATLAB to evaluate the performance of the proposed cycle under different operating conditions. Optimization using a particle swarm optimization (PSO) algorithm is performed to minimize the levelized cost of electricity (LCOE) and determine the optimum design conditions of the cycle. The optimization results show that for a 100 MW cycle, the overall thermal efficiency and LCOE are 0.521 and $52.819/MWh, respectively. The turbine inlet temperature of the gas turbine and s-CO 2 cycles are found as the most influential parameters on the thermoeconomic performance of the triple cycle. The proposed triple cycle shows an excellent waste energy recovery potential and superiority over a very thermodynamically efficient cycle from the literature, which included a gas turbine topping cycle and a complex cascade s-CO 2 power cycle used a bottoming cycle. The proposed triple cycle shows up to 0.9% points higher efficiency while it has fewer heat exchangers and turbomachinery than the cycle from the literature. [ABSTRACT FROM AUTHOR]

In this work, an exergoeconomic analysis is applied to the power cycle of a concentrated solar plant for its design improvement. A supercritical CO2 cycle connected with the exothermic reactor of a thermochemical storage unit is considered. The analysis is conducted with the goal of highlighting the advantages of exergoeconomic analysis while suggesting changes to both the design parameters and the system configuration. Starting from the plant configuration which guarantees the maximum efficiency, the exergoeconomic analysis is iteratively applied with the goal of reducing the unit cost of electricity. The analysis is conducted in a way that cost functions of the components can be substituted with the cost analysis of specific designs. This is a big advantage of this procedure, which is suitable for applications in which economic analysis requires a detailed knowledge of the system characteristics. The procedure is then validated comparing the results with those obtained through mathematical optimization. [ABSTRACT FROM AUTHOR]

In this work, a biomass-fired proton exchange membrane fuel cell integrated with organic Rankine cycle and thermoelectric generator using different gasification agents is proposed for the cogeneration of power and heat as well as hot water production. Both models are comprehensively analyzed and compared from thermodynamic, thermoeconomic, and environmental aspects. A parametric study is performed to evaluate the influence of major decision parameters on the output power, energy and exergy efficiencies, CO 2 emission index, and total cost rate of both models. Furthermore, the best model is optimized using genetic algorithm method in MATLAB. The results reveal that using steam as the gasification agent is more suitable in terms of economic and environmental performance indicators. Referring to the exergy and exergoeconomic assessment, in both models, afterburner is one of the significant sources of irreversibility and proton exchange membrane fuel cell has the highest cost of inefficiencies. Results of multi-objective optimization indicate that the output power and total cost rate of the model using steam as the gasification agent are 1.849 kW and 5.094 $/h. Moreover, scatter distribution of the significant variables shows that biomass moisture content and figure of merit are sensitive variables that should be kept at their lowest value. • A biomass-fired PEM fuel cell system is proposed for power/heat/hot water production. • Proposed system is compared using steam and air as the gasification agents. • A parametric study is performed to assess the influence of major variables on the models performance/environmental aspects. • Using steam as the gasification agent leads to lower economic and environmental indices and higher performance indicators. • For the best model, at the optimum point, the output power and total cost rate are 1.849 kW and 5.0942 $/h, respectively. [ABSTRACT FROM AUTHOR]

• PV integration increases the electric output but can benefit or hinder the water production. • The PV plant integration allows to decrease the TCE and TCW. • A pareto frontier between the TCE and TCW was obtained. • In the Pareto frontier, the PV size has a trade-off with the CSP and MED size. A detailed annual performance and thermoeconomic analysis of a Concentrated Solar Power plant coupled to a Photovoltaic and a Multi-Effect Distillation plants (CSP + PV + MED) were performed using an extensive methodology based on an hourly simulation. The aim was to assess the impact of the PV integration into the CSP + PV plant and to evaluate the sizing of the plant in terms of the design parameters (PV plant size, solar multiple, Thermal Energy Storage capacity, and numbers of MED units) that allow achieving the lowest thermoeconomic electric and water costs (TCE and TCW). Results show that PV integration mainly increases the electric output but could increase the water production depending on the PV and CSP plants' sizes. Moreover, the PV plant cost is mainly allocated to electricity, decreasing the TCE, while on the TCW it has a moderate impact. Finally, it was found that the PV plant and the CSP plant size has contradictory roles between the costs, where the minimum TCE is obtained for large PV plant with an undersized CSP plant and one MED unit, and the minimum TCW is obtained for small PV plant with an oversized CSP plant and a large MED plant (5 units). [ABSTRACT FROM AUTHOR]

• Two flash geothermal integrated with trans- and supercritical ORCs are introduced. • A thermoeconomical model is developed to evaluate the proposed systems. • The design parameters of the ORC evaporator are defined for various conditions. • A multi-objective optimization is presented to find the optimum operating condition. • The performance of the systems is compared from viewpoint of energy and economic. In this research, the integration of an enhanced single flash geothermal cycle with a transcritical organic Rankine cycle (TORC) is proposed. To discover the feasibility and thermoeconomic improvement, the proposed system is investigated and compared thermoeconomically with a subcritical ORC integrated to single flash geothermal. Thermoeconomic evaluation is conducted with consideration Pseudo-critical point effect in supercritical condition as well as Bauman rule in geofluid turbine. The considered key parameters to conduct a parametric study are heat source temperature, separator pressure, and geofluid condenser pressure. To perform the thermoeconomic analysis, the heat transfer areas, as well as overall heat transfer coefficients of all heat exchangers, are calculated. Moreover, the total cost rate and levelized cost of energy for the considered systems are obtained. The results reveal that the heat source temperature plays an important role in the power production variation, while the separator and flash condenser pressures are kept constant. An increment of 20 °C in the heat source temperature leads to an increase of up to 22% in generated power for both considered systems. Also, based on the comparative study, a combination of the flash-transcritical ORC cycle has 7.2% higher power production compared to the combination of flash-subcritical one. A multi-objective optimization based on the genetic algorithm method is performed. The optimization results show that the energy and exergy efficiencies, exergy destruction rate, and total cost rate is well improved in single flash-TORC compared to the subcritical one. [ABSTRACT FROM AUTHOR]

This study presents an investigation of a CO 2 plume geothermal and supercritical CO 2 Brayton (CPG-sCO 2) combined cycle using solar energy as auxiliary heat source. This combined cycle may help solve the problems of CO 2 sequestration and geothermal energy utilization simultaneously. The CPG production is heated by a solar power generation system with solar tower and molten salt. Then a recompression sCO 2 cycle utilizes geothermal energy and solar energy directly. A solution procedure is performed to analyze the thermoeconomic performance of the CPG-sCO 2 combined cycle. Results show that the combined cycle has an optimal main compressor inlet pressure and split ratio for maximum combined cycle efficiency. It can achieve 19.57% by genetic algorithm (GA) optimization, which is 5.65% and 4.07% higher than CPG systems with indirect sCO 2 cycle and organic Rankine cycle, respectively. Moreover, it indicates that the combined cycle efficiency and total capital cost have opposite variation trends with the increase of parameters, including main compressor inlet pressure (p 5), split ratio (sr), well distance (d 8,11) and injection temperature (T 8). Based on multi-objective GA optimization and optimal solution selection, it is concluded that the most thermoeconomic CPG-sCO 2 combined cycle has a combined cycle efficiency of 18.09% and a total capital cost of $5.959 × 107, respectively. Findings suggest that the CPG-sCO 2 combined cycle has potential to combine CO 2 sequestration with geothermal energy utilization. • A CPG-sCO 2 combined cycle with auxiliary solar energy source was studied. • This combined cycle coupled CO 2 sequestration with geothermal energy utilization. • The CPG-sCO 2 combined cycle had a maximum efficiency of 19.57%. • Its efficiency is 5.65% and 4.07% higher than CPG with indirect sCO 2 cycle and ORC. • Most thermoeconomic combined cycle had η cc of 18.09% and C cur,cc of $5.959 × 107. [ABSTRACT FROM AUTHOR]

• Thermoeconomic analysis using the exergy cost allocation method based on energy levels. • Steam and power cogeneration system with a high-temperature heat pump. • Energy level-based thermoeconomic analysis is suitable for cogeneration systems. • The electricity unit cost is more sensitive to the part load than the steam unit cost. • Electricity is always costlier than steam for the investigated cogeneration systems. Thermoeconomic analysis is considered a strong tool for cogeneration systems to optimize operation and set prices. In this paper, an absorption-compression heat pump enhanced steam and power cogeneration system is proposed, in which a heat pump is used to upgrade low-temperature waste heat and generate steam. The thermoeconomic performance of the proposed system is investigated under design and off-design conditions using a new thermoeconomic analysis approach with energy level-based cost allocation. As a result, the unit exergy costs of electricity and steam under the design conditions are 2.249 kW/kW and 1.714 kW/kW, respectively. The cost of electricity is higher than that of steam, and this result is opposite to that obtained by a conventional thermoeconomic method (2.063 kW/kW and 2.339 kW/kW, respectively). The costs of electricity and steam increase along with the decreasing engine load under off-design conditions, and the cost of electricity is always higher than that of steam. Finally, the thermoeconomic analysis method with energy level-based cost allocation can obtain more reasonable results and is more suitable for cogeneration systems. [ABSTRACT FROM AUTHOR]

Despite the fact that humidification-dehumidification (HDH) desalination systems can be driven by various renewable or waste heat energies, many of the available renewable technologies are expensive in some parts of the globe. Hence, proposing and developing high-efficient mechanical-based HDH units can be an encouraging alternative which is more highlighted in recent investigations. In pursuance of this objective, three innovative mechanical-driven HDH units are simulated and the results are compared with each other. The simulated hybrid desalination system consists of a HDH unit and an ethane ejector expander transcritical refrigeration cycle (ethane-EETRC). The simulated hybrid systems can produce freshwater and cooling load, simultaneously. The main difference between each system is the proposal of using two-stage compression and humidification-dehumidification processes at different scenarios. The results display that a maximum freshwater of 17.3 m3/day can be achieved when a two-stage HDH unit is used with a single-stage compression ethane-EETRC, resulting in CGOR (cogeneration-based gain output ratio), exergy efficiency, and cooling load of 6.56, 17.13% and146.9 kW, respectively. However, to achieve as high cooling load as 161.8 kW - with CGOR, exergy efficiency, and freshwater of 5.19, 18.1% and 11.97 m3/day, respectively - a configuration with two HDH units coupled with a two-stage ethane-EETRC is highly commendable. Moreover, the cost evaluation results indicated that unit overall cost of the product (UOCP) of the hybrid system with two HDH units integrated with a two-stage ethane-EETRC and the hybrid set-up with a two-stage HDH unit integrated with a single-stage ethane-EETRC is calculated 8.2 $/GJ and 8.93 $/GJ, respectively. At last, an intensive parametric evaluation of some influential parameters is presented. • Ejector expander transcritical refrigeration cycle (EETRC) with ethane is used to drive a HDH unit. • Three scenarios are defined on the basis of the single- and two-stage HDH/EETRC concepts. • Freshwater rate is high when a two-stage HDH unit is coupled with a single-stage ethane-EETRC. • Amount of cooling load is high when two HDH units are coupled with a two-stage ethane-EETRC. [ABSTRACT FROM AUTHOR]

• A SOFC cogeneration system with an ORC waste heat recovery system is proposed. • The performance of the dual-loop ORC system with 20 working fluids is explored. • Thermodynamic and economic multi-objective optimisations are performed. • Exergy efficiency of 52% with 969 kW electricity and 564 kW cooling is achieved. • The system LCoE is up to 74% lower than those of traditional SOFC configurations. A novel combined-cycle system is proposed for the cogeneration of electricity and cooling, in which a dual-loop organic Rankine cycle (ORC) engine is used for waste-heat recovery from a solid oxide fuel cell system equipped with a gas turbine (SOFC-GT). Electricity is generated by the SOFC, its associated gas turbine, the two ORC turbines and a liquefied natural gas (LNG) turbine; the LNG supply to the fuel cell is also used as the heat sink to the ORC engines and as a cooling medium for domestic applications. The performance of the system with 20 different combinations of ORC working fluids is investigated by multi-objective optimisation of its capital cost rate and exergy efficiency, using an integration of a genetic algorithm and a neural network. The combination of R601 (top cycle) and Ethane (bottom cycle) is proposed for the dual-loop ORC system, due to the satisfaction of the optimisation goals, i.e. , an optimal trade-off between efficiency and cost. With these working fluids, the overall system achieves an exergy efficiency of 51.6%, a total electrical power generation of 1040 kW, with the ORC waste-heat recovery system supplying 20.7% of this power, and a cooling capacity of 567 kW. In addition, an economic analysis of the proposed SOFC-GT-ORC system shows that the cost of production of an electrical unit amounts to $33.2 per MWh, which is 12.9% and 73.9% lower than the levelized cost of electricity of separate SOFC-GT and SOFC systems, respectively. Exergy flow diagrams are used to determine the flow rate of the exergy and the value of exergy destruction in each component. In the waste-heat recovery system, exergy destruction mainly occurs within the heat exchangers, the highest of which is in the LNG cooling unit followed by the LNG vaporiser and the evaporator of the bottom-cycle ORC system, highlighting the importance of these components' design in maximising the performance of the overall system. [ABSTRACT FROM AUTHOR]