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The heat recovery steam generator (HRSG) can be regarded as a heat exchanger, which uses the heat rejected from the gas cycle to supply steam for the vapor cycle. HRSGs are consisted of many tube bundles (or harps). Supplying a duct burner in the upstream of an HRSG necessitates constructing the first bundle using different finned-tube materials with dissimilar fin configurations including unequal fin-pitch sizes. The computational fluid dynamics (CFD) has been widely used to study the flow through tube bundles; however, considering a fixed fin-pitch size for all rows of the finned-tubes. There is no trace of numerical analyses to treat tube bundles with unequal fin pitch sizes, apparently, because there are major challenges for the classical strategies, say unified-domain approach, to simulate tube bundles constructed from tubes with different fin configurations. This work introduces the splitted-domain approach as an innovative strategy to pass over the challenges with using the unified-domain approach. Then, these two approaches are used to model the superheater module of a real HRSG with available online measured data. The calculated Nusselt numbers and pressure drops indicate that the splitted-domain approach provides more accurate results than the unified one in simulating tube bundles constructed from tubes with dissimilar fin configurations. [ABSTRACT FROM AUTHOR]

In liquefied natural gas (LNG) power plants, a significant amount of heat and cold energy is consumed to capture and store carbon dioxide (CO2) emitted during the combustion of fossil fuels. The proposed system addresses this problem by utilizing the temperature difference between waste heat and cold energy as a power source to generate electricity. In this study, a novel waste heat and cold energy recovery system for a postcombustion LNG power plant was developed using an organic Rankine cycle (ORC). To design the proposed system, a process model was developed with the following five parts: (i) LNG vaporization, (ii) natural gas combined cycle (NGCC), (iii) amine scrubbing, (iv) CO2 liquefaction, and (v) CO2 injection. In the proposed system, waste LNG cold energy is used for lean amine cooling and CO2 liquefaction. The liquefied CO2 was pressurized to meet the injection pressure requirements. The ORC uses high-temperature exhaust gas from the NGCC as the heat source and high-pressure liquefied CO2 as the heat sink. The economic feasibility of the proposed system was demonstrated by an economic assessment, with the net profit evaluated by a sensitivity analysis considering variations in water, electricity, and equipment costs. Consequently, the proposed system exhibited an 18.6% increase in net power production compared to the conventional system. In addition, the net profit of the proposed system exhibited a 76.7% increase compared to the conventional system, confirming its economic feasibility. [ABSTRACT FROM AUTHOR]

To assess the electricity cogeneration potential in the Minas Gerais cement industry with thermodynamic cycles is the main purpose of this study. The potential was estimated based on Minas Gerais cement sector data. The Kalina cycle, the organic Rankine cycle, and the conventional Rankine cycle were technically and economically assessed. The technical evaluation considered the thermodynamic modeling with optimization including the mass, energy, entropy, and exergy balances and the heat transfer calculations for heat exchangers. The economic evaluation considered the economic modeling including the calculation of electric power generated specific cost, the total investment, cash flow, and payback. The result shows that the greatest irreversibilities are concentrated in the turbines and evaporators. The Kalina cycle confirmed more generated power and exergetic efficiency, but in terms of thermal efficiency, the values were very similar between the cycles. The three cycles can cover more than 35% of the energy demand, which means a considerable reduction in cement manufacturing costs. All cycles reveal a payback value lower than 3 years, a considerable value of cash flow, and high competitiveness in the current tariff scenario. The electricity cogeneration potential in the Minas Gerais cement industry is near 100MW, and it is in the south-central region of Minas Gerais, where there is a greater population and energy demand concentration. This potential could save emissions of around 282,913 tCO2/year. [ABSTRACT FROM AUTHOR]

Renewable energy-based compact energy-generation systems based on the organic Rankine cycle (ORC) can be employed to meet the ever-growing thirst for affordable and clean energy. The overall performance and effectiveness of ORC systems are constrained by the low efficiency of the gas expander, specifically the positive displacement expander, which is responsible for energy conversion from the working fluid. This low-efficiency scenario can be significantly improved by employing a control valve to regulate and restrict the flow of the working fluid into the expander. A control valve can effectively curve the loss of costly compressed and energized working fluids by allowing them to expand in the expander chamber before discharging through the outlet port. They can thus be used to regulate the amount of energy yield and output power. In this work, two direct drive rotary valves (DDRVs) operated by a stepper motor (SM-DDRV) and rotary solenoid (RS-DDRV) are suggested, and the behavior of the valves is examined. The effect of friction and temperature on the valve response is also studied. Additionally, the effect of inlet control valves on the overall system performance of the limaçon expander is assessed. Thermodynamic properties such as the isentropic efficiency and filling factor are also computed. The effect of leakage due to valve response delay is analyzed at different inlet pressures. The performance indices are compared to the expander performance without any inlet valve. The SM-DDRV setup results in a 14.86% increase in isentropic efficiency and a 220% increase in the filling factor, whereas the RS-DDRV performs moderately with a 2.58% increase in isentropic efficiency and an 80% increase in the filling factor compared to a ported expander. The SM-DDRV provides better performance indices compared to the RS-DDRV and without valve setups. However, the performance of the limaçon expander with the SM-DDRV is sensitive to the inlet pressure and degrades at higher pressure. Overall, the valves proposed in this work present key insights into improving the performance characteristics of gas expanders of ORC systems. [ABSTRACT FROM AUTHOR]

Small nuclear power plants are a promising direction of research for the development of carbon-free energy in isolated power systems and in remote regions with undeveloped infrastructure. Improving the efficiency of power units integrated with small modular reactors will improve the prospects for the commercialization of such projects. Power cycles based on supercritical carbon dioxide are an effective solution for nuclear power plants that use reactor facilities with an initial coolant temperature above 550 °C. However, the presence of low temperature rejected heat sources in closed Bryton cycles indicates a potential for energy saving. This paper presents a comprehensive thermodynamic analysis of the integration of an additional low-temperature organic Rankine cycle for heat recovery to supercritical carbon dioxide cycles. A scheme for sequential heat recovery from several sources in S-CO2 cycles is proposed. It was found that the use of R134a improved the power of the low-temperature circuit. It was revealed that in the S-CO2 Brayton cycle with a recuperator, the ORC add-on increased the net efficiency by an average of 2.98%, and in the recompression cycle by 1.7–2.2%. With sequential heat recovery in the recuperative cycle from the intercooling of the compressor and the main cooler, the increase in efficiency from the ORC superstructure will be 1.8%. [ABSTRACT FROM AUTHOR]

This study aims to explore additional fluids beneficial for coastal thermal energy converter (CTEC) operation. Ammonia's thermodynamic properties, characterized by higher condensation temperatures and pressures, demand significantly elevated operating pressures, resulting in a substantial energy load for efficient operation. Thus, exploring alternatives such as R134a becomes crucial, particularly considering its potential as a better working fluid for power generation in a Rankine cycle. The research methodology involves employing computational fluid dynamics (CFD) simulations alongside experimental investigations to examine the performance of an axial turbine concept under different working fluids. The results obtained indicate that R134a is the most appropriate working fluid for an axial turbine within a CTEC, outperforming ammonia, thereby implying significantly better operational efficiency. [ABSTRACT FROM AUTHOR]

This work proposes a pumped thermal energy storage (PTES) integrated into the power block of a concentrated solar power plant. The power block operates under a Hybrid Rankine–Brayton (HRB) cycle using propane as the working fluid. During PTES charging, some thermal energy is obtained from a dedicated compressor (additional to that of the HRB cycle), which is stored. During discharge, both compressors (HRB and PTES) are off, restoring the consumed energy and resulting in about a 13% increase in nominal power output. The system is also able to store thermal energy that would otherwise be rejected through the condenser if the PTES were turned off, leading to efficiency improvements in some cases. Considering the 2022 Spanish electricity market prices, the proposed PTES integration with 4 h of storage is feasible. The levelized cost of storage is calculated and compared to those of other PTES systems, achieving around a 40% reduction compared with an equivalent PTES Rankine. These results encourage future studies where the proposed PTES could be integrated into other power cycles that include a recompression process. [ABSTRACT FROM AUTHOR]

The LNG cold energy utilization system primarily integrates additional power cycles during the gasification process to harness the cold energy released in this process efficiently. This study introduces a combined cooling and power (CCP) system, which comprises a cascade organic Rankine cycle (ORC), an air conditioning refrigeration (ACR), and a direct expansion cycle (DEC). Furthermore, the thermodynamic and economic analyses of the CCP system were evaluated, and the optimization of each influence parameters was performed by the genetic algorithms, such as the composition of the quaternary mixed working fluid (Methane: Ethane: Propane: i-Butane), condensation pressure, evaporation pressure, and the first-stage expansion pressure within the system. According to the simulation results, the suggested overall exergy destruction of the CCP system proposed by this work is reduced by 13.18% under optimized conditions, with a maximum net power generation of 230.38 kW and an exergy efficiency of 45.58%. Economic analysis reveals that the system's investment cost, annual economic benefits, and levelized energy cost are 2.02 × 106 $, 2.75 × 105 $, and 0.10 $/kWh, respectively. With the system's official operation, the investment cost will be recovered within 8.61 years. • A novel process for power generation combined with refrigeration has been proposed. • Optimized the composition of the quaternary mixed working fluid and key operation parameters. • The net out power and exergy efficiency are enhanced up to 13.40% and 7.21%, respectively. • The payback period of the system is as low as 8.61 years. [ABSTRACT FROM AUTHOR]

Modern conditions for the development of nuclear energy in Russia impose maneuverability requirements on nuclear power plants. In particular, this is dictated by the energy development strategy of Russia for the period up to 2035, which sets the task of attracting nuclear power plants to participate in regulating the daily unevenness of the electrical load in the range of up to 50% of the rated power. In addition, nuclear power plants will be involved in the primary frequency regulation, which will oblige them to carry out unloading operation during the day. Since nuclear power plants in the power system always carry a base load, all these circumstances force us to look for ways to provide a base load. The traditional solution has been the use of pumped storage power plants (PSPP). But due to the specifics of their construction, the combination of nuclear power plants + pumped storage power plants is not effective. It is more effective to use a hydrogen complex based on the electrolysis of hydrogen and oxygen for the purpose of using them to overheat the working fluid in the steam turbine cycle of nuclear power plants during peak periods of electrical load in the power system. In this case, it is critically important to assess the rate of peak power release based on the criterion of the working life of the most important components of the turbine unit rotor - rotor blades and disks. In the article, based on well-known methods and models for fatigue wear, the working life of the working blades and disks of the first stage of the HPC rotor, as the most susceptible to cyclic wear, is assessed using the example of the C-1000-60/1500 turbine under conditions of using steam-hydrogen superheating of fresh steam. [ABSTRACT FROM AUTHOR]

This study conducts conventional and advanced exergy, exergo-economic, and exergo-environmental analyses and comparisons of two tri-generation systems driven by solid oxide fuel cells (SOFCs) and gas turbines (GTs). The proposed systems mainly consist of SOFC, GT, heat recovery steam generator (HRSG), (organic) Rankine cycle, and heat exchanger. The analysis results indicate that the biggest cost rates of exergy destruction and component in both systems appear in SOFCs being 4.4333 $/h and 4.2760 $/h, while the highest environmental impact rates combined with exergy destruction and component in systems 1 and 2 are found in afterburner and HRSG, which are 645.9569 mPts/h and 849.2659 mPts/h. Compared to the conventional analyses, the advanced analyses demonstrate that air compressors own the largest avoidable-endogenous parts of cost rates, while HRSG of system 1 and steam turbine (ST) of system 2 own the highest avoidable-endogenous parts of environmental impact rates being 165.8482 mPts/h and 115.2299 mPts/h. • Two novel tri-generation systems driven by solid oxide fuel cells are proposed. • Conventional and advanced exergy-based analyses are performed and compared. • The biggest cost rates of exergy destruction and component appear in SOFCs. • The advanced exergo-economic and exergo-environmental factors are improved. [ABSTRACT FROM AUTHOR]

In pursuit of sustainable development and mitigation of the intermittency challenge associated with solar energy, this study proposes a hybrid solar system integrating waste heat incineration alongside solar power generation and distinct heat provision. Leveraging the superior energy efficiency of the organic Rankine cycle (ORC) in medium- and low-temperature scenarios, a parabolic trough collector (PTC) is selected for its cost-effectiveness and long-term operational reliability. Dowtherm A and toluene are identified as the optimal working fluids for the PTC and ORC, respectively. To optimize this complex system, a combination of artificial neural networks (ANNs) and multi-objective optimization via non-dominated sorting genetic algorithm II (NSGA-II) is employed, streamlining the optimization process. Thermal dynamic simulations are executed using Engineering Equation Solver (EES, V11) to validate the proposed system's performance. TOPSIS is employed to identify the optimal solution from the Pareto frontier. The results indicate that the hourly cost of the system stands at USD 43.08, with an exergy efficiency of 22.98%. The economic analysis reveals that the solar collector constitutes the most significant portion of the total initial cost, representing 53.2%, followed by the turbine, thermoelectric generator (TEG), and waste heat incineration, in descending order of costliness. [ABSTRACT FROM AUTHOR]

The thermodynamic analysis of an increasing-pressure endothermic power cycle (IPEPC) integrated with closed-loop geothermal energy extraction (CLGEE) in a geothermal well at a depth from 2 km to 5 km has been carried out in this study. Using CLGEE can avoid some typical problems associated with traditional EGS technology, such as water contamination and seismic-induced risk. Simultaneous optimization has been conducted for the structural parameters of the downhole heat exchanger (DHE), the CO2 mixture working fluid type, and the IPEPC operating parameters. The CO2-R32 mixture has been selected as the optimal working fluid for the IPEPC based on the highest net power output obtained. It has been found that, when the DHE length is 4 km, the thermosiphon effect is capable of compensating for 53.8% of the pump power consumption. As long as the DHE inlet pressure is higher than the critical pressure, a lower DHE inlet pressure results in more power production. The power generation performance of the IPEPC has been compared with that of the organic Rankine cycle (ORC), trans-critical carbon dioxide cycle (t-CO2), and single-flash (SF) systems. The comparison shows that the IPEPC has more net power output than other systems in the case that the DHE length is less than 3 km, along with a DHE outer diameter of 0.155 m. When the DHE outer diameter is increased to 0.22 m, the IPEPC has the highest net power output for the DHE length ranging from 2 km to 5 km. The application scopes obtained in this study for different power generation systems are of engineering-guiding significance for geothermal industries. [ABSTRACT FROM AUTHOR]

Small nuclear power plants can provide a stable, carbon-free energy supply to civil infrastructure and industrial enterprises in remote regions isolated from unified energy systems. More than 70 projects of small modular reactors are currently being developed by IAEA member countries; several low-power power units are already supplying thermal and electrical energy to consumers. One of the main limitations standing in the way of widespread dissemination of this technology is the high specific capital cost of a low-power nuclear power plant; therefore, new scientific and technical solutions are needed in this industry. Increasing the thermodynamic efficiency of power cycles of small modular reactors can become a driver for reducing the cost of supplied electrical energy. This paper presents the results of a comprehensive thermodynamic analysis of existing and promising power cycles for small modular reactors. In addition to traditional steam power cycles, cycles using non-traditional working fluids, including carbon dioxide, freons, and helium cycles, are considered. Optimal sets of thermodynamic parameters were determined to ensure maximum net efficiency of electricity production. For water-cooled reactor plants, a maximum efficiency of 33.5% at an initial temperature of 300 °C could be achieved using a steam turbine cycle. It was revealed that for reactor plants with liquid metal and liquid salt coolant in the range of initial temperatures above 550–700 °C, the maximum thermal efficiency was provided by the Brayton recompression cycle with a carbon dioxide coolant: the net electrical efficiency exceeded the level of steam turbine plants, with intermediate superheating of the steam, and could reach a value of 49.4% at 600 °C. This makes the use of these cycles promising for low-power nuclear power plants with a high initial temperature. In small gas-cooled reactor plants with a helium coolant, the use of a binary cycle consisting of a helium Brayton cycle and a steam-powered Rankine cycle provided an efficiency of 44.3% at an initial helium temperature of 700 °C and 52.9% at 1000 °C. This was higher than in the Brayton cycle with a recuperator, with a minimum temperature difference in the heat exchanger of 20 °C: the efficiency was 40.2% and 52%, respectively. Also, the transition to power cycles with non-traditional working fluids will lead to a change in the operating conditions of turbomachines and heat exchangers. [ABSTRACT FROM AUTHOR]

Combination of different power cycle scenarios is of prime importance in achieving maximum energy utilization from solar‐driven multigeneration systems. To fulfill such objective, the present article proposes a novel energy distribution system, leveraging a combination of direct‐fed organic Rankine cycle (ORC) and a bottom‐cycled arrangement of Kalina cycle system (KCS) and double‐effect absorption refrigeration cycle (DEARC) within a parabolic trough solar collector powered trigeneration system. The study explores three different ORC configurations: simple ORC; ORC equipped with internal heat exchanger (ORC‐IHE) and regenerative ORC (RORC). It is shown that although higher efficiencies are achievable from a larger portion of PTSC energy absorbed by the ORC, the ORC energy absorption is limited by ORC evaporator temperature differences, and there is unused energy that can be recovered by the KCS, based on the proposed energy system. The results indicate that the addition of bottoming KCS leads to a considerable increase in the exergy efficiency of ORC, ORC‐IHE and RORC‐based systems by 11.7%, 30.7% and 32.6%, respectively. The impact of different ORC configurations, key ORC parameters and various organic working fluids on the energetic/exergetic efficiencies is also examined to find the optimal configuration. In terms of overall energetic/exergetic efficiencies, the highest performance belongs to ORC (78.4%/30.4%) while the lowest energetic and exergetic efficiencies belong to ORC‐IHE and RORC, respectively (56.3% and 25.65%). On the basis of a comparative study with the available literature, these values are higher than what is already reported for similar solar‐driven multigeneration systems. Appropriate thermal match and lower exergy destruction in the KCS, and bottoming cycle arrangement of the DEARC are the main reasons for such enhanced performance. This research not only contributes valuable insights into efficient solar‐driven systems but also sets a new benchmark for performance metrics in the existing literature. [ABSTRACT FROM AUTHOR]

We examined how working-fluid properties impact the organic Rankine cycle (ORC) and bottoming cycle in a cogeneration system, and compared the sizes of turbines according to different working fluids. Working fluids R123, R245fa, and R245ca were selected based on factors such as the T-s diagram slope, environmental impact, and safety. The latent heat for vaporization significantly impacted ORC and bottoming-cycle performance. R123 produced the lowest bottoming cycle output of 38.49 MW and an ORC output of 1.95 MW. R245ca required a bigger turbine size, leading to the largest volume flow rate of 20 m3/s at the ORC turbine outlet. The bottoming-cycle output was 38.68 MW and the ORC generated 2.61 MW, which were the highest. R245fa showed promise in terms of compact turbine size due to its smallest volume flow of 14.96 m3/s at the ORC turbine outlet, even though the overall output was 250 kW lower than that of R245ca. [ABSTRACT FROM AUTHOR]

The processing of traditional Chinese medicine (TCM) plays an important role in the clinical application, which usually has the function of "increasing efficiency and reducing toxicity". Polygonum multiflorum (PM) has been reported to induce hepatotoxicity, while it is believed that the toxicity is reduced after processing. Studies have shown that the hepatotoxicity of PM is closely related to the changes in chemical components before and after processing. However, there is no comprehensive investigation on the chemical changes of PM during the processing progress. In this research, we established a comprehensive method to profile both small molecule compounds and polysaccharides from raw and different processed PM samples. In detail, an online two-dimensional liquid chromatography coupled with quadrupole-orbitrap mass spectrometry (2D-LC/Q-Orbitrap MS) was utilized to investigate the small molecules, and a total of 150 compounds were characterized successfully. After multivariate statistical analysis, 49 differential compounds between raw and processed products were screened out. Furthermore, an accurate and comprehensive method for quantification of differential compounds in PM samples was established based on ultra-high performance liquid chromatography/Q-Orbitrap-MS (UHPLC/Q-Orbitrap-MS) within 16 min. In addition, the changes of polysaccharides in different PM samples were analyzed, and it was found that the addition of black beans and steaming times would affect the content and composition of polysaccharides in PM significantly. Our work provided a reference basis for revealing the scientific connotation of the processing technology and increasing the quality control and safety of PM. [ABSTRACT FROM AUTHOR]

The demand for the power grid system's capacity to undergo peak-shaving is increasing as the proportion of renewable energy rises. In China, nuclear power units usually only provide a base load operation in the view of safety and economic considerations, but they do not provide load adjustment services, which undoubtedly increases the pressure of grid load adjustment. In this paper, a novel flexibility load adjustment strategy of the CHP nuclear unit is studied, which is achieved by introducing the thermal storage tank (TST) into the Rankine cycle without changing the output of the nuclear reactor. The AP1000 pressurized water reactor nuclear power unit for combined heat and power is taken as an example, and the thermodynamic model is established through the water vapor equation. Furthermore, the reference system is simulated for the goal of minimizing the imbalance between power supply and demand, and the flexibility–environment–economy benefits are evaluated. The results show that the heat storage/release of the TST may achieve power output flexible adjustment of the nuclear unit, and the power imbalance of the reference energy system is reduced from 1107.99 MWh to 457.24 MWh, a reduction of 58.73%. The introduction of a 600 MWh TST can enable the reference unit to contribute 335 MWh of peak electricity within the reference day. From the perspective of replacing the power generation output increment of coal-fired power units with equal amounts, it can achieve a reduction of 106.09 tons of coal consumption in the case day, which means that 277.73 tons of CO2 emissions can be reduced. The profit of the reference unit can be improved by CHY 70,125 via participating in load adjustment in the case day if following the time-of-use electricity price. [ABSTRACT FROM AUTHOR]

This paper proposes a novel solar-based polygeneration system for simultaneous power generation, desalination, hydrogen-production, and refrigeration. The system integrates parabolic trough solar collectors, multi-effect distillation, polymer electrolyte membrane electrolyzer, Kalina cycle, organic Rankine cycle, Brayton cycle, and ejector cooling. Solar energy and waste heat from the Brayton cycle provide energy input. Power generation is achieved via the Brayton, Kalina, and organic Rankine cycles. The multi-effect distillation unit produces freshwater while the electrolyzer generates hydrogen. The ejector system supplies cooling. A comprehensive steady-state energy and exergy analysis evaluates the thermodynamic performance. The system attains 32.269 MW net power output and ejector COP of 0.3193. The overall energy and exergy efficiencies are 38.45% and 35.64%, respectively. The combustion chamber exhibits maximum exergy destruction. Exergoeconomic analysis determines associated costs and investment feasibility. Integrating multiple technologies into a system with solar input enhances efficiency, sustainability, and environmental benefits. • Presents novel solar multi-generation system integrating power, hydrogen, water and cooling generation • Validated methodology analyzes thermodynamic performance providing insights on efficiencies • Exergy destruction analysis identifies optimization opportunities in integrated solar systems • Showcases potential of intricate integration of solar, desalination, hydrogen and power for sustainable energy • Modular and scalable system design enables flexibility for different applications and demands [ABSTRACT FROM AUTHOR]

Symmetric-structure metal-supported solid oxide fuel cells and electrolysis cells (MS-SOFCs, MS-SOECs) offer several advantages over conventional solid oxide cells, including the use of inexpensive materials, high mechanical strength, and rapid ramp-up ability. Aggressive operation of MS-SOCs in fuel cell mode is well-established, including extremely fast start-up, redox tolerance, and imbalanced pressure. Here, we extend dynamic operation to MS-SOCs in SOEC mode with high steam content for both small button cells and a large rectangular cell, including: steam cycling, thermal cycling, redox cycling and power cycling. Steam cycling entailed switching between 3:97 and 50:50 steam:hydrogen ratio. For thermal cycling, the temperature was rapidly varied between 150 °C and 700 °C for 50 cycles. Redox cycling involved switching the steam side gas between 50 % humidified H 2 and 50 % humidified N 2 for 5 cycles. Power cycling was performed by operating the cell under variable current density, resulting in cell voltage between 1.3 V and 2.8 V. Degradation rates for each testing strategy were compared to a baseline cell, and found to be similar. The excellent tolerance to dynamic operation increases confidence that MS-SOECs will be compatible with dynamic or intermittent renewable resources. • MS-SOEC show significant stability under variable steam content during steam cycling. • Small and large MS-SOECs exhibit excellent tolerance to rapid thermal cycling. • MS-SOECs display minimal degradation during redox cycling. • The cells show remarkable adaptability to power cycling. • Scaling up to a larger cell maintains similar performance and stability. [ABSTRACT FROM AUTHOR]

This paper proposed a single-piston free piston expander-linear generator (SFPE-LG) prototype applied to organic Rankine cycle systems. Two valve timing control strategies, namely, time control strategy (TCS) and position control strategy (PCS), were developed. Based on the experimental data, a back propagation neural network (BPNN) prediction model was established. The effects of structural parameters such as neural network layers, transfer function, training function, hidden layer nodes, and learning rate on the prediction accuracy of this BPNN model were discussed. The training and prediction accuracy of the BPNN model was verified using 5-fold cross-validation and Wilcoxon signed-rank test. Moreover, the BPNN model was integrated with a genetic algorithm to predict and optimize the maximum output power of the SFPE-LG. The results showed that the BPNN model used to predict the motion characteristics and output performance of the SFPE-LG exhibits strong learning ability and high prediction accuracy. Notably, the prediction accuracy of the BPNN model is significantly higher under the PCS compared to TCS. The effect of hidden layer nodes on mean square error (MSE) and correlation coefficient (R) is greater than that of the learning rate. When the number of hidden layer nodes exceeds 30, the BPNN model consistently achieves low MSE and high R. The optimization results showed that the SFPE-LG can obtain a maximum output power of 141.69 W under the TCS, when the working parameters are inlet pressure of 0.7 MPa, intake duration of 35 ms, load resistance of 67 Ω, and expansion duration of 104 ms, respectively. [ABSTRACT FROM AUTHOR]

Liquid hydrogen (LH 2) storage is a feasible way to store and transport hydrogen with the advantage of high energy density, which is of great significance to the development of hydrogen energy and environmental protection. However, the energy consumption, economic costs and carbon emissions of large-scale hydrogen liquefaction plants tend to be high because of the large cooling capacity needed at liquid hydrogen temperature. To improve thermodynamic efficiencies, reduce economic costs and CO 2 emissions, a new hydrogen liquefaction process coupled with mixed refrigerant (MR) precooling cycle and steam methane reforming (SMR) is proposed. Furthermore, liquefied natural gas (LNG) cold energy is used to precool the process and evaporated natural gas is used as raw material for SMR to produce hydrogen. Multi-objective optimization method is introduced to comprehensively optimize the specific energy consumption (SEC), economic costs and CO 2 emissions. The thermodynamic model and optimization program are established in Aspen HYSYS and MATLAB. The SEC, economic costs and CO 2 emissions of the optimized results that take the balance of economic costs and CO 2 emissions are 9.38 kWh/kg, 5.419 × 106 $/year and 1.898 × 107 kg/year, respectively. Besides, it is found that there is no trade-off relationship between SEC and economic costs. • A new hydrogen liquefaction process coupled with MR cycle and SMR is proposed. • Multi-objective optimization of SEC, CO 2 emission and economic costs is performed. • The result reduces CO 2 emissions by 27.64 % at the cost of 24.99 % increasing in economic costs. • There is no trade-off relationship between SEC and economic costs. • The costs of feed hydrogen account for the highest proportion of economic costs. [ABSTRACT FROM AUTHOR]

Biomass fuel utilization is a crucial energy supply task for sustainable development due to its renewable and high energy density nature. Considering an innovative thermal design for a biomass combustion process, this study proposes an innovative multigeneration system for generating combined cooling, heating, power, and freshwater. The proposed system comprises a biomass combustor, an organic Rankine cycle, a multi-effect desalination, an absorption chiller, and a liquefied natural gas (LNG) regasification unit. The system is simulated using the Aspen HYSYS software, and its energy, exergy, economic, and environmental aspects are analyzed comprehensively. According to the simulation, the system produces 10403 kW of electricity, 4927.4 kW of cooling, 1743 kW of heat, and 19.83 kg/s of freshwater. Hence, the energy and exergy efficiencies are computed as 67.1% and 37.15%, respectively. Based on the simulation condition, the total cost rate and product unit cost associated with the proposed system are 568 $/h and 14.89 $/GJ, respectively. The study also incorporates a comprehensive sensitivity study based on two principal parameters; i.e., LNG stream rate and temperature of the combustion gas leaving the evaporator of organic Rankine cycle, on the production capacity of products, energy and exergy efficiencies, primary energy saving, and product unit cost. [ABSTRACT FROM AUTHOR]

Thermal power plants are pivotal in meeting global energy demands, yet enhancing their efficiency and sustainability remains an enduring challenge. While previous studies have scrutinized energy and exergy analyses of distinct plant components, there's a scarcity of comprehensive reviews integrating findings across diverse plant types. This paper bridges this gap by presenting a comprehensive synthesis of recent advancements in energy and exergy studies across coal, gas, biomass, oil, and combined cycle plants. The review focuses on critical aspects: optimizing operations through modeling and advanced controls, economic evaluations encompassing costs and revenue, and assessing environmental impacts such as emissions and water use. Achieving a balance between performance, cost-effectiveness, and environmental responsibility is crucial for sustainable thermal power generation worldwide. It requires an integrated approach that considers technical, economic, and environmental factors to ensure efficiency, profitability, and minimal adverse effects on health and climate. Key findings emphasize that, in most cases, the boiler emerges as the primary source of exergy destruction, accounting for over 50% of losses across varied plant configurations. Turbines and condensers also significantly contribute to energy losses. Supercritical and ultra-supercritical power plants exhibit higher efficiencies compared to subcritical counterparts. Integrating waste-to-energy technologies with coal plants holds promise, offering efficiency improvements and reduced environmental impact. Optimizing parameters such as pressure and temperature, along with component advancements, shows potential in curbing losses. These optimization endeavors have showcased a notable up to 6% enhancement in exergy efficiency. This review underscores the critical role of ongoing thermodynamic modeling and assessments in steering towards more sustainable thermal power generation. In summary, this paper delivers valuable insights into performance benchmarks and delineates effective strategies for augmenting thermal power plant efficiency through exhaustive energy and exergy analyses. [Display omitted] • Exergy analysis provides a broader perspective than energy analysis alone. • Boiler subsystem is a major source of exergy destruction (52-85% of total losses). • Supercritical and ultra-supercritical plants display higher efficiencies than subcritical ones. • Optimization of parameters like temperature and pressure can boost exergy efficiency by up to 6%. • Advanced combined cycles achieved over 50% efficiency, indicating potential for lower CO2/kWh. [ABSTRACT FROM AUTHOR]

In this work, an efficient predictive model for screening working fluids of the Organic Rankine Cycle (ORC) was proposed by using 120 °C of low-temperature waste heat. The proposed model was implemented by combining the structural parameters of working fluids and the optimal performance of the ORC system. Four quantum chemical descriptors (molecular volume, HOMO orbital energy, mulliken electronegativity, molecular polarity index) were screened to characterize the Quantitative Structure-Property Relationship (QSPR) model. The model was constructed using Support Vector Regression. The results demonstrate that the Leave-One-Out determination coefficient of the model achieves a commendable value of 0.8997, thereby underscoring its robustness. The model's practical application reveals its proficiency in predicting the optimal efficiency of the working fluids within the ORC, surpassing the results obtained with the commonly working fluids, R245fa. A novel ORC process was proposed based on the QSPR. The total annual costs (TAC) for the proposed process obtained a reduction of 2.01%, and exergy destruction experienced a decrease of 3.13%. The reduction of the annual operational cost and equipment costs were 30.63% and 5.37%, respectively. To summarize, the new model facilitates efficient screening of working fluids and offers a theoretical foundation for the industrial application of such fluids. [Display omitted] [ABSTRACT FROM AUTHOR]

The energy sector faces a pressing need for significant transformation to curb CO2 emissions. For instance, Czechia and Germany have taken steps to phase out fossil thermal power plants by 2038, opting instead for a greater reliance on variable renewable energy sources like wind and solar power. Nonetheless, thermal power plants will still have roles, too. While the conventional multistage axial turbine design has been predominant in large-scale power plants for the past century, it is unsuitable for small-scale decentralized projects due to complexity and cost. To address this, the study investigates less common turbine types, which were discarded as they demonstrated lower efficiency. One design is the Elektra turbine, characterized by its velocity compounded radial re-entry configuration. The Elektra turbine combines the advantages of volumetric expanders (the low rotational speed requirement) with the advantages of a turbine (no rubbing seals, no lubrication in the working fluid, wear is almost completely avoided). Thus, the research goal of the authors is the implementation of a 10 kW-class ORC turbine driving a cost-effective off-the-shelf 3000 rpm generator. The paper introduces the concept of the Elektra turbine in comparison to other turbines and proposes this approach for an ORC working fluid. In the second part, the 1D design and 3D–CFD optimization of the 7 kW Elektra turbine working with Hexamethyldisiloxane (MM) is performed. Finally, CFD efficiency characteristics of various versions of the Elektra are presented and critically discussed regarding the originally defined design approach. The unsteady CFD calculation of the final Elektra version showed 46% total-to-static isentropic efficiency. [ABSTRACT FROM AUTHOR]

In this study, a power cycle (IPEC), with an increasing pressure endothermic process in a downhole heat exchanger (DHE) and a CO2-based working fluid mixture, was developed for geothermal power generation. The increasing pressure endothermic process, which cannot be achieved in a conventional evaporator on the ground, was realized using the gravitational potential energy in the DHE. The parameters of the power cycle and the structural size of the DHE were optimized simultaneously. Using CO2-R32 as the working fluid of the IPEC provides the highest net power output. The net power generated with the IPEC was compared with a single-flash (SF) system, a trans-critical CO2 (t-CO2) system, and an organic Rankine cycle (ORC) under the same heat source and sink conditions. Six selection maps were generated for choosing the optimum power cycle for electricity production, in which four power generation systems (ORC, t-CO2, IPEC, and SF) were included, and two DHE diameters (0.155 m and 0.22 m) were investigated. It was found that the IPEC system had more net power output than the other three systems (ORC, t-CO2, and SF) under the conditions that the geofluid's mass flow rate was less than 10 kg/s and its temperature was lower than 180 °C. [ABSTRACT FROM AUTHOR]

The organic Rankine cycle (ORC) has received a lot of attention in recent years due to its wide application in energy recovery and the use of low‐temperature energy sources. In this article, the energy, exergy, and economic analyses of a high‐temperature ORC (HTORC) in combined heat and power production mode have been performed. In this system, the heating water at 90°C for domestic or industrial purposes is provided in the HTORC condenser. Two working fluids, hexamethyldisiloxane (MM) and siloxane mixture (MDM), have been evaluated and compared in HTORC. The system has been modeled in engineering equation solver software and key parameters such as energy efficiency and exergy of the system, output power, heat‐to‐power ratio, and levelized cost of electricity (LCOE) have been calculated. The energy and exergy efficiency of the system for the two working fluids MM and MDM are equal to 40.8%, 45.6%, 22.45%, and 19.3%, respectively. From the point of view of energy and exergy, the working fluid MM performs better. The LCOE of the system with MM working fluid is equal to 0.5946 US$/kWh, which is slightly higher than MDM working fluid (0.5702 US$/kWh). [ABSTRACT FROM AUTHOR]

This research entails the simulation and thermodynamic evaluation of a combined solar‐powered system that is intended to achieve the energy necessary to construct factories in areas where other sources of energy are not available. The system comprises five major circuits: (1) a parabolic trough that collects solar energy and passes it to downstream circuits via an evaporator, (2) an organic Rankine cycle that generates electricity for devices and factories, (3) a proton exchange membrane electrolysis unit that produces hydrogen from pure water, (4) a methanation unit that produces gas by combining hydrogen and carbon dioxide, and (5) a reverse osmosis (RO) unit that purges seawater to produce freshwater. This investigation studies the efficiency of energy and exergy, the destruction rate of exergy, and the economic value of system components as a whole. The system is represented by the technical equation solver, and the results are obtained as a result. This research employs the genetic algorithm and Technique for Order of Preference by Similarity to Ideal Solution method to locate the most effective point. The achieved outcomes include a maximum total system efficiency of 54.935% and a minimum total cost of 2.578 $/GJ. Dated to the optimal point, the power generated is 305.5 kW, the required power of a single‐cell electrolyzer is 293.8 W, the mass flow rate of methane and hydrogen production is 448.92 kg/hr ${kg}/{hr}$ and 225.64 kg/h, respectively. The water volume generated by RO is 35.25 m3/h, and the total cost of the investment is 85.57 $/h. [ABSTRACT FROM AUTHOR]

In this paper, a multigeneration cycle of electricity, cooling, and Bitcoin whose energy source is geothermal, has been subjected to energy, exergy, and economic analyses. The cycle under consideration includes the steam cycle (upstream cycle), the carbon dioxide cycle (downstream cycle), and the liquid–gas line to absorb the heat dissipated by the carbon dioxide cycle. In this cycle, the steam cycle condenser acts as the carbon dioxide cycle evaporator. Part of the electricity generated by this cycle is used to generate Bitcoins. Energy and exergy efficiencies at baseline (excluding Bitcoin production) are 45.8% and 38.1%, respectively. In this cycle, if more power is spent on producing Bitcoin as a product, the energy and exergy efficiencies of the cycle are reduced. Because Bitcoin itself is not valuable in terms of energy and exergy. Considering the average price of Bitcoin during the years 2015–2022 and if 100% of the electricity generated by the system is spent on Bitcoin production, the payback period in 2018, 2021, and 2022 when the price of Bitcoin is equal to $13,412.4, $21,398.8, and $47,743.0, respectively, are less than the baseline. Therefore, the production of Bitcoin with a variety of renewable energies can be considered as a solution. Of course, it should be noted that large changes in the price of Bitcoin can affect the issue of economic benefit. [ABSTRACT FROM AUTHOR]

The utilization of waste energy contributes to reducing carbon emissions and mitigating global warming. A novel heat integration system comprising an Internal Combustion Engine (ICE), Boiler, and Organic Rankine Cycle (ORC) coupling is techno‐economically examined in this study. The feasibility of waste heat recovery from industrial boilers of a thermal power plant (Gadoon Textile Mills Limited, Pakistan) having 2.66‐MW capacity was assessed. This was done by efficiently harnessing the waste heat from boiler exhaust gas by coupling an existing system with an ORC. A steady‐state simulation model of the ICE‐Boiler‐ORC system was developed through Power Plant Simulator and Designer (PPSD) software to perform a multiparametric study. Additional heat power (3710 kW) was extracted from the boilers' waste gases through ORC. Consequently, the overall plant thermal efficiency was enhanced from 61.84% to 82.68% and the overall net electric efficiency of the existing system was increased by 0.9%. The average payback period was found 4.2 years based on different plant operation scenarios and equipment prices (Chinese or European origin). Therefore, the proposed system holds significant technical and economic potential for enhancing energy efficiency through low‐grade waste heat and proves to be economically viable with a short payback period. [ABSTRACT FROM AUTHOR]

Regasification of liquefied natural gas (LNG) releases significant cooling potential, but improper usage can easily lead to wastage of resources and environmental pollution. The study developed an integrated air separation system and Organic Rankine Cycle (ORC) power generation system to effectively harness the inherent cold energy within LNG. Two distinct optimization algorithms, the Non-Dominated Sorting Genetic Algorithm II (NSGA-II) and the Particle Swarm Optimization (PSO), were employed to determine the optimal operational parameters. The results showed the superior performance of PSO over NSGA-II, as demonstrated by the exergy efficiency, net output power, and levelized cost of energy at 78.12 %, 2.29*1011 kW, and 0.0665 $/kWh, respectively. Additionally, an assessment of various factors influencing the system's performance was conducted. The performance of both conventional and proposed systems was studied under varying regasification rates. The findings indicated that incorporating the cold recovery and storage unit enhanced the efficient utilization of LNG cold energy, resulting in an increased valley-to-peak ratio of the total power output from 0.03 in the conventional system to 0.5. The proposed system exhibits alignment with the energy consumption demands of users, and this study is anticipated to furnish a theoretical foundation for harnessing the cooling capacity of liquid hydrogen. [Display omitted] • The novel utilization of LNG cold energy by combining air separation with ORC. • PSO is superior than NSGA-II for optimization: 14.4 % decrement in LCOE. • PSO: 17.9 % and 7.0 % increment in the exergy efficiency and net output power. • Both LNG steady state and fluctuating in regasification rates were investigated. • The valley-to-peak ratio of the system's power output was increased to 0.5. [ABSTRACT FROM AUTHOR]

In this paper, a novel ammonia-hydrogen-electricity cogeneration system is developed. To mitigate the cost associated with hydrogen storage and transportation in later stages, the proposal is to utilize high-temperature ammonia production instead of conventional hydrogen production. A comparative analysis between ammonia and transportation for hydrogen is conducted to assess cost efficiencies. To improve the system efficiency, a supercritical CO 2 Brayton cycle is applied as the power generation cycle. This choice exhibits superior parameter compatibility with the system compared to the Rankine cycle. The study scrutinizes the impacts of different energy utilization sequences and varying process parameters of the power generation cycle on the system's performance to ascertain the most optimal configuration. The results indicate that the Brayton cycle is more suitable for integration with the nuclear-IS thermochemical hydrogen production system, significantly enhancing the power generation capacity of the ammonia-hydrogen-electricity cogeneration system. These improvements result in 18.8 % increase in power generation efficiency and a 9.3 % boost in overall energy efficiency of the system. Subsequent to this enhancement, the system attains an impressive energy efficiency of 47.0 % along with a system exergy efficiency of 63.4 %. This study introduces an innovative approach for optimizing and enhancing the energy efficiency of a cogeneration system by employing nuclear energy as a high-temperature heat source for hydrogen (ammonia) production. • A novel ammonia-hydrogen-electric cogeneration system is developed. • The system bolsters efficiency by 9.3 % through a synergistic Brayton cycle coupling. • Conducted an assessment and comparison of the transportation and storage expenses associated with hydrogen and ammonia. [ABSTRACT FROM AUTHOR]

In the light of increasingly valuable resources and a trend towards more efficient processes pushed by climate change, distributed Waste Heat Recovery (WHR) is an important element in the transformation of the energy supply. In recent years, however, WHR systems have often been optimized and implemented for steady-state applications. In this paper, dynamic system modeling and a Steam Rankine Cycle (SRC) pilot plant with 40 kWel are used to investigate applications unutilized thus far for the conversion of high-temperature waste heat into electricity using a shell boiler with 1.27 m3 of liquid water for short-term energy storage. In addition to experimental investigations of the storage system as an Uninterruptible Power Supply (UPS) and the input and output of +/−100% electrical power peaks for grid-assistive operation, a control concept for the use of volatile waste heat is developed from a model-based controller design up to a Model Predictive Control (MPC) with the help of a dynamic system simulation. Based on the validated model and experimental measurement data, outlooks for concrete applications with higher storage capacity and power are provided. [ABSTRACT FROM AUTHOR]

Hydrogen is a potential alternative fuel for combustion engines with its higher renewability, near zero emission, and excellent combustion performance. The direct-injection (DI) engine provides favorable brake thermal efficiency (BTE), less dependence on the hydrogen purity but sacrificing the production cost. This study explores both effects of turbocharging and DI on the energy and exergy balances, as well as the cost-effective analysis on a spark ignition engine. Results reveal the exergy efficiencies are related to the engine speeds and loads, while its maximum is 58.8% with 3500 rpm and 1.4 MPa of brake mean effective pressure. The DI system increases 2.6% maximum BTE from the port fuel injection. However, the exhaust energy proportions exceed 32.8% and 18.9% at the maximum power and BTE. An organic Rankine cycle is utilized to improve the exergy to the maximum of 58.9%. The valuable experience can be widely applied for hydrogen engine design. • The performance of a turbocharged direct-injection hydrogen engine is studied. • The BTE of the DI hydrogen engine increases 2.6% from the PFI hydrogen engine. • The exhaust energy account for the total energy from 18.1 to 37.4%. • The highest available exergy efficiency can reach 58.8%. • The BTE in DI HICE is more sensitive to the engine load than speed. [ABSTRACT FROM AUTHOR]

This research article presents an innovative approach to enhance sustainable power generation and grid support by integrating real-time modeling and optimization with Molten Salt Energy Storage (MSES) and a Supercritical Steam Cycle (s-SC). As renewable energy usage grows, intermittent resource availability challenges grid stability and reliable power supply. To address this, we develop a system that merges real-time modeling and optimization for precise control of MSES and s-SC components. This integration ensures uninterrupted energy generation, storage, and distribution, optimizing renewable energy use during high-demand periods. Mathematical models and simulations assess the system's dynamic behavior, performance, and economic viability. Rigorous techno-economic analysis highlights cost-effectiveness and environmental benefits. Findings reveal exceptional energy efficiency and grid support, making it a promising solution for sustainable power generation and grid stability amid renewable energy growth. Real-time modeling and optimization emerge as crucial components in modern energy systems. The Combined Heat and Power (CHP) system achieves 56% energy efficiency with off-design impacts considered and 63.61% without. Also, the overall system exergy efficiency decreased from 73.36% at design to approximately 63.55% under off-design scenarios. Regarding the economic aspect, the levelized cost of storage (LCOS) for the CHP system is estimated at 114.4 €/MWh with off-design conditions and 106.8 €/MWh without. [ABSTRACT FROM AUTHOR]

The fluctuation of heat source conditions results in off-design operation of the radial inflow turbines (RIT) in the organic Rankine cycle. However, the flow loss characteristics of RIT under off-design conditions have not been completely revealed. The entropy production theory has the advantage of determining the quantity and location of energy dissipation, which is used to evaluate the energy loss of RIT under different conditions. In addition, the order of operating parameters on the RIT energy loss is determined by the orthogonal experimental method. The results show that each entropy production term and the entropy production of different components increase with the increase in the inlet pressure and inlet temperature, while they decrease with the increase in the outlet pressure of the RIT. Under different operating conditions, the turbulent dissipation and wall dissipation are the main cause of RIT energy loss, which are closely related to vortices and high velocity gradients in the flow field. The rotor and diffuser contribute the main energy loss of RIT. However, the volume-average entropy production and area-average entropy production of the stator and rotor are higher than those of other components. In addition, the wall shear is the main cause of the stator energy loss, while the turbulent dissipation dominants the rotor energy loss. The outlet pressure has the greatest impact on the turbulent entropy production and wall dissipation. [ABSTRACT FROM AUTHOR]

Analysis of thermodynamic parameters' effects on the S-CO2 recompression Brayton cycle for recovering the main engine exhaust gas waste heat of an ocean-going 9000 TEU container ship are carried out first in this paper. NSGA-II algorithm-based multi-objective optimizations are conducted to maximise net power output and exergetic efficiency as well as to minimise the levelized cost of energy (LCOE). The final optimal result from Pareto front solutions is decided by decision-making processes. The results show that the LCOE increases along with the enhancement of net power output and exergetic efficiency, and the maximal objectives always appear near the upper boundary of exhaust gas temperature. The final optimal result decided by TOPSIS decision-making has higher rationality and accuracy than that obtained by the LINMAP method. Regarding the final optimal results of triple-objective and dual-objective optimizations obtained by the TOPSIS method, the former achieved more reasonable results, since its optimal net power output and exergetic efficiency are 1.29% and 5.11% higher than the latter, while its LCOE increased by 2. 28% as a result of the increase of the net power output. The recompression Brayton cycle is better for recovering the exhaust gas waste heat in ships compared with the simple recuperative cycle without recompression. [ABSTRACT FROM AUTHOR]

This paper proposes a novel SOFC based cogeneration system, consisting of biomass co-gasification, SOFC power generation and ORC waste heat recovery, to achieve the efficient and clean utilization of poultry litter. Based on the conceptual design, the energy, exergy and exergo-economic analysis are conducted, including sensitivity analysis, uncertainty analysis and multi-objective optimization. Results show that when using straw as the co-gasification biomass with poultry litter, the highest energy utilization efficiency of 44.70 % is obtained with the electricity and heat production of 162.02 kW and 52.41 kW, respectively. The biomass gasifier and the SOFC stack have the highest exergy destruction, accounting for 24.43 % and 19.99 % of the total. Sensitivity analysis presents complex results concerning mass fraction of poultry litter, water content, equivalent air ratio and water-carbon ratio, etc. The optimal solution for the current optimization problem is obtained. When poultry litter mass fraction is fixed at 25 %, T SOFC = 852 °C and u f = 0.73, the exergy efficiency is obtained as 41.95 % and the overall exergy cost per unit is obtained as 42.35 $/GJ. This paper investigates a novel cogeneration system relying on the biomass co-gasification of poultry litter, providing a new solution for poultry litter treatment and sustainable development of agriculture, forestry and husbandry. [Display omitted] • Biomass co-gasification, SOFC and ORC are integrated for poultry litter treatment. • Comprehensive energy, exergy and exergo-economic analysis are carried out. • Sensitivity analysis, uncertainty analysis and operational optimization are conducted. • High-value utilization process of the low-calorific poultry litter is proposed and studied. [ABSTRACT FROM AUTHOR]

This article presents energy, exergy and economic analyses and tri-objective optimization of a hybrid system that comprises a proton exchange membrane fuel cell and a recuperative-regenerative organic Rankine cycle. The novelty of this study is the utilisation of a recuperative-regenerative organic Rankine cycle rather than the basic configuration of the organic Rankine cycle to recover waste heat from the fuel cell. The simulation results showed that the proposed system generates a net power of 1195.6 kW, with an exergy efficiency of 44.37% and a product cost rate of 160.78 $/h at the base condition. The hybrid system is found to be more efficient and cost-effective as compared to a standalone fuel cell with 15.05% and 15.06% improvements in energy and exergy efficiencies, respectively, and a 9.28% decrement in unit product cost. The fuel cell is the component with maximum exergy destruction rate of 636.72 kW, accounting for 90.62% of the total exergy destruction. Further, it is also observed that the fuel cell accounts for 89.2% of the total levelized cost rate of the hybrid system. Then a tri-objective optimization is carried out on the system using Pareto Envelope-based Selection Algorithm-II with net power output, exergy efficiency, and product cost rate as the objective functions. The optimization results showed that the proposed system generates a net power of 1271.52 kW, with an exergy efficiency of 49.48% and a product cost rate of 152.62 $/h. It implies that at the optimal conditions, the hybrid system's net power and exergy efficiency increased by 6.35% and 11.51%, respectively, and the product cost rate was reduced by 4.98%. Finally, this study showed that the inclusion of recuperative-regenerative organic Rankine cycle as compared to other organic Rankine cycle layouts improved the performance of the suggested hybrid system compared to similar other systems reported in the literature. [Display omitted] • A novel RR-ORC integrated PEMFC system is proposed, analyzed and optimized. • Tri-objective optimization of the hybrid plant is performed by applying PESA-II. • Energy, exergy, and economic (3E) analysis is performed at optimal conditions. • A hybrid system is more efficient and cost-effective compared to a standalone PEMFC. • Current density has the greatest influence on the performance of the hybrid system. [ABSTRACT FROM AUTHOR]

This work researches producing electricity and hydrogen production performance of a solar pond integrated with parabolic trough solar collectors. The system consists of parabolic trough solar collectors and a solar pond with a surface area of 100 m2 and 200 m2, an organic Rankine cycle operating with n-butane for electricity production, a proton exchange membrane for generating hydrogen, and a mushroom production unit. The system was operated for five mass flow rates m ˙ 1 = 0.350 k g / s , m ˙ 2 = 0.355 k g / s , m ˙ 3 = 0.360 k g / s , m ˙ 4 = 0.365 k g / s , m ˙ 5 = 0.370 k g / s. To improve the overall system performance, n-butane is selected as the operating fluid in the organic Rankine cycle and the waste heat of the organic Rankine cycle was used to heat the mushroom production unit. In addition, the preheating water produced by the solar pond was transferred to the parabolic trough solar collectors via a pump. The temperature of this preheated water was quickly raised by the parabolic trough solar collectors and pumped to the organic Rankine cycle. Thus, the organic Rankine cycle's electricity generation performance was also tried to be increased. With efficient electricity produced, the hydrogen production performance of the proton exchange membrane was improved. Thus, the amount of hot water, electricity, and hydrogen produced in the integrated system, the organic Rankine cycle, the parabolic trough solar collectors, and the energy and exergy efficiencies of the entire system were determined daily for five different masses. As a result, for five different masses, it was found in which mass the system performed the best. The whole system was analyzed with the engineering equation solver program. It was found that the system performs best at noon for all mass flow rates. It was also found that the performance of the system, the amount of electricity, and the hydrogen it produced increased as the amount of mass decreased. It was seen that hydrogen can be produced as 534.32 g and 519.06 g for m ˙ 1 and m ˙ 5 in a day, respectively. The energetic and exergetic efficiencies of the system were also found to be a maximum of 13.77% and 5.79% for m ˙ 1. • Hydrogen production of a different solar integrated system. • Thermodynamic performances of the parts of the system and overall system. • The comparison of the hydrogen production for five different mass flow rates. • The effect of thermal energy on hydrogen production in a day. [ABSTRACT FROM AUTHOR]

In this research, a proton-conducting membrane fuel cell is used in conjunction with a gasifier for producing electricity with air considered as the gasification agent. The simultaneous electricity, heat, and hot water generation of these two when coupled with an Organic Rankine Cycle (ORC) installed within a Thermoelectric Generator (TEG) was studied. Additionally, to utilize the electricity generated from various parts of the process; i.e. the fuel cell, organic Rankine cycle turbine, and the thermoelectric generator, the reverse osmosis (OR) water desalination unit was coupled to the process. The aforementioned system was studied and analyzed based on thermodynamic and thermos-economic aspects. A parametric study was also carried out to analyze the effect of main factors on power output, energy/exergy yield, and the total cost of each system. Finally, a dual objective optimization was achieved by taking the main factors into consideration and using a genetic algorithm. Results indicated that the work generated by the system was not significant; however, the amount of hot water produced was relatively promising. Based on exergy and exergoeconomic evaluation, the After-Burner is an important non-renewable energy source while the fuel cell has a higher inefficiency cost which could be due to low work generation. Results indicate that the moisture in the biomass and the figure of merit, are important parameters that have to be kept as low as possible. The energy yield of the fuel cell was calculated to be 45.05%. Additionally, considering the optimized operating point, pure power output and system cost rate will be 1.81 KW and 5.15 $/hr respectively. • Proposing a novel cycle based on fuel cell for electricity generation. • Adding nanomaterial on the fuel cell for increasing the performance. • Double-objective optimization of the related energy system. [ABSTRACT FROM AUTHOR]

The adverse environmental impacts of fossil fuels is becoming a major concern considering the climate changes. In this respect, the H 2 as a carbon-free energy carrier has absorbed interest of researchers and policy makers to pay more attention to this field. In this regard, the solar energy driven frameworks are of major importance due to the abundance of solar energy as well as being a clean energy resource. However, the solar based systems suffer from lower efficiency compared to conventional fossil fuel-based systems due to large exergy destructions. One way to solve this problem and to enhance solar-based system performance is employment of nanoparticles for improving heat transfer characteristics of solar thermal loop. Present research is an attempt in this regard in which effects of employment nanofluid instead of the pure solar salt is investigated in a solar power tower system. The solar power tower unit supplies required energy to run a steam cycle for power generation and a thermochemical H 2 production unit for co-generation of power and H 2. Feasibility evaluations are carried out based on thermodynamic laws and exergy-based analyses as well as economic investigations are conducted to assess the system performance and multi-objective optimization is conducted to specify the optimum operation of system. A parametric evaluation is carried out to consider how design variables affect the system performance, prior to implementation of multi-objective optimization. The results have revealed positive effect of nanofluid application instead of pure solar salt and indicated enhancement of 4 − 5 % on technical performance. In addition considering the economic investigations, the nanofluid employment bring about a reduction by around 3 − 4 % in unit cost of product of cogeneration plant, depending on the operating conditions. • Solar power tower is integrated with thermochemical hydrogen production unit. • Nanoparticles are applied to enhance the solar loop performance. • System performance is examined from thermodynamic and economic standpoints. • Improvement of around 4–5% is attained with incorporation of nanoparticles. [ABSTRACT FROM AUTHOR]

Due to the fact that biomass fuel is capable of powering multi-generation systems, has a high-efficiency performance, and produces fewer harmful gases, biomass fuel can prove to be a valuable heat source. In this regard, this study introduces a new biomass-fueled power and hydrogen generation scheme. There are three subsystems involved in the study: a biomass-based gas turbine cycle, a steam flash cycle, and an electrolyzer unit. To begin, a parametric analysis is performed on the system from the perspectives of thermodynamics, thermoeconomic, and the environment. As a next step, four effective variables are evaluated for single-objective and bi-objective optimizations in order to determine the optimal working conditions. The results of bi-objective optimization indicate 48.78% and 41.40% energy and exergy efficiencies for the presented system, separately, with 8093 kW output power, 86.1 kg/day hydrogen production, 8684 t/MWh CO 2 emission, and 27.9 $/MWh Levelized Cost of Product. Compared to the base condition, hydrogen production grows 29.78%, but output power drops by 1.14%. Furthermore, hydrogen Production Optimum Design accounts for the maximum amount of hydrogen production in optimal conditions, producing 94.73 kg/day. The gasifier destroys the most exergy under base and optimum conditions. • Proposal of a novel power/hydrogen cogeneration system including a gas turbine cycle. • The utilization of a steam flash cycle integrated with an electrolyzer to generate more power. • Evaluating system performance using thermodynamic, thermoeconomic, and environmental metrics. • The highest cost is related to the gas turbine in the optimized condition based on output power. • The proposed system performs better than the existing related ones in the literature. [ABSTRACT FROM AUTHOR]

This work discusses the novel application of proton exchange membrane fuel cells (PEMFC) in the transport sector as well as portable applications. This kind of fuel cell produces a considerable quantity of heat while in operation. This quantity of heat is about 45–60% of entire energy composition of the hydrogen that is introduced into the cell. A correctly built cooling system must be used to efficiently eliminate produced heat from the stack to extend the stack's life and preserve its efficiency throughout its entire lifespan. Using appropriate thermal management techniques coupled with exploiting possibilities for fuel cell heat recovery may significantly improve size, cost, etc., while also reducing its total energy consumption. It is possible to collect and utilise the heat produced by PEMFC in other applications. A thorough analysis of heat recovery possibilities in this type of fuel cells is presented in this investigation. Similarly, the study further touched on the need for experimental studies into waste heat recovery from proton exchange membrane fuel cells as most of the recent work being championed are modelling based and does not really present a real life scenario of the system investigated. The need for investigations into the environmental performance of the waste heat recovery unit coupled to the proton exchange fuel cell system is also another important research direction that must be considered in future studies. Finally most of the studies on waste heat recovery from fuel cells have largely employed the use of organic Rankine cycle but other types of thermodynamic cycles like Kalina cycle is however recommended for further investigations due to their range of operation hence making them suitable for low and high temperature proton exchange membrane fuel cells. • Role of PEMFC in the transport sector as well as portable applications was discussed. • PEM Fuel cell in Combine Heat and Power Applications was illustrated. • Waste heat recovery in FCs was summarised. [ABSTRACT FROM AUTHOR]

A Flame-assisted Fuel Cell is the combination of the Solid Oxide Fuel Cell with fuel-rich combustion. In this work, two different bottoming power cycles i.e., the RSCBC and the DORC are employed to the waste heat recovery of a methane-fueled Flame-assisted Fuel Cell (FFC). Energy and exergy analyses of the FFC-RSCBC combined cycle show that this combination improves the energy and exergy efficiencies from 18.62% to 22.91% and 18.05%–22.21%, respectively. The cathode inlet air is preheated by the exhaust gases from fuel-lean combustion in the FFC-DORC combined cycle, which increases the efficiency. The improvements in energy and exergy efficiencies are 20.54–20.94% and 19.91–20.3% respectively. Comparison of the performance of the proposed cycles show that the FFC-RSCBC generates more power compared to the FFC-DORC ( W ˙ F F C − R S C B C = 184.4 k W , W ˙ F F C − D O R C = 168.6 k W) and the exergy loss of FFC-RSCBC and FFC-DORC is 22.02 kW and 3.46 kW, respectively. • Two bottoming cycles are used to utilize waste heat of a flame-assisted fuel cell. • The cathode inlet air is preheated by the exhaust gases from fuel-lean combustion. • The proposed configurations are assessed from the energy and exergy viewpoints. • A parametric study is performed to show the effects of important parameters. • The exergy efficiencies of the proposed cycles are determined as 22.21 and 20.3%. [ABSTRACT FROM AUTHOR]

The use of fuel cell (FC) is considered one of the methods of producing electricity with relatively high efficiency. So, it has attracted many researchers' attention to develop and improve its performance. The present study deals with the technical-economic optimal design of a hybrid power generation system based on a Proton Exchange Membrane (PEM) FC combined with an Organic Rankine Cycle (ORC). ORC is used to recover the generated heat in PEM FC. The decision variables of this study include FC operating pressure and temperature, current density, FC area, the quantity of FC, and operating parameters of the ORC system, including HRVG PPTD, condenser PPTD, and refrigerant mass fraction in zeotropic mixture. In this study, three zeotropic mixtures, including R11-R245fa, R11-R123, and R123-R245fa, are studied as the working fluid of the ORC system. The objective functions considered to be optimized are the system's exergy efficiency and total cost rate (TCR). Finally, it is observed that the highest exergy efficiency is obtained using the zeotropic mixture R11-R245fa with a value of 54.15%, and the lowest TCR is obtained with the mixture R11-R123 with a value of 0.65 $/s. Zeotropic mixture R11-R123 has the exergoenvironmental index, environmental damage effectiveness index, and exergy stability factor of 0.5506, 1.277, and 0.4750, respectively. • A hybrid electricity generation system including PEM FC and ORC is analyzed. • Exergy Efficiency and economic analysis are considered for system evaluation. • Three novel zeotropic mixtures are examined as the working fluid of the ORC system. • A Parametric Study and optimization are conducted in this research paper. [ABSTRACT FROM AUTHOR]

It is crucial to evaluate the impact of key parameters of multi-generation systems on their performance characteristics in order to develop efficient systems. The present study conducts parametric analysis of a PTSC-driven trigeneration system with a novel energy distribution based on direct-fed ORC and bottom-cycled arrangement of double-effect absorption refrigeration cycle and Kalina cycle system. Three different ORC structures (simple, regenerative, and ORC integrated with intermediate heat exchanger - IHE) are proposed. Effect of key ORC parameters namely ORC evaporator pinch point temperature and pump inlet temperature is examined on the thermodynamic performance of systems. Decrease of pinch point temperature enhances overall efficiencies and heating power in all three configurations, and increases (decreases) the net electrical power for ORC and regenerative ORC (RORC) based systems. This also enhances the cooling power of the RORC based system, though it has no impact on the cooling power of the ORC and ORC-IHE based systems. Reduction of the ORC pump inlet temperature increases overall exergy efficiency in all hybrid systems and overall energy efficiency in the ORC and ORC-IHE based systems, whereas it slightly decreases for the RORC based system. Based on a comparative study, performance of the proposed systems is found to be higher than related solar-driven multi-generation systems in the literature. [ABSTRACT FROM AUTHOR]

The increasing demand for green hydrogen and power production necessitates the development of novel and upgraded power generation technologies. The solid oxide fuel cell combined heat and power (SOFC–CHP) system is a promising solution due to its high efficiency, clean operation, and fuel flexibility. In practical terms, SOFCs can operate using a variety of fuels such as alcoholic fuel, hydrogen, ammonia, etc. Recently, methanol and ammonia have become noteworthy alternative fuel options as it possesses advantages such as low transportation cost and high hydrogen storage capacity. In this paper, we have established two SOFC–CHP models fueled by methanol or ammonia integrated with the steam Rankine cycle. A comprehensive thermodynamic model is proposed for energy and exergy analyses. Sensitivity analysis is performed to study the system's characteristics. The results show that the SOFC–CHP system fueled by ammonia exhibits superior performance, the maximum electrical power, efficiency, and exergy efficiency is 430W, 7% and 10% greater than the methanol fueled system. The operating temperature is about 30K higher in methanol supplied system. The largest thermal power difference can reach 0.65 kW. Overall, the ammonia fueled SOFC–CHP system shows greater potential than that fueled by methanol. [Display omitted] • Using ammonia as fuel can improve energy and exergy efficiency by 7% and 10%. • Methanol fueled system requires almost half fuel than that supplied by ammonia. • The operating temperature is about 30K higher in methanol supplied system. • The largest thermal power difference can reach 0.65 kW. • The exergy destruction of preheat process accounts for the majority of both systems. [ABSTRACT FROM AUTHOR]

In this study, 143 different working fluids have been analyzed for Rankine and Brayton cycles in terms of performance characteristics such as power, thermal and exergy efficiency, and EFECWOD. The selection of working fluid is a significant consideration in the design of both these cycles, as it can importantly affect the performance and efficiency of the system. As of late, there has been growing interest in investigating the effects of various working fluids on the performance characteristics of these cycles. This article aims to determine the ten best among different working fluids according to the determined criteria using the Technique for Order of Preference by Similarity to Ideal Solution, which is a multi-criteria decision method. In the decision-making process, the importance scale of the analytical hierarchy process was used to determine the weight values of the criteria to be used in the TOPSIS analysis to obtain more accurate results. Artificial Neural Network method is employed to identify the optimal working fluid as well. As a conclusion of this thermodynamic analysis of the performance characteristics for Rankine and Brayton cycles using various working fluids, the Rankine cycle achieved the maximum power of 12,277 kW, the maximum efficiency of 93 %, and the maximum EFECWOD value of 9962 kJ/m3 with hydrogen, helium, and dimethylcarbonate as the respective working fluids. Furthermore, hydrogen exhibits the highest power output of 2493 kW in the Brayton cycle. Nitrogen demonstrates the highest efficiency at 44 %, while R141b achieves the highest exergy efficiency at 98 %. Lastly, the fluid with the highest EFECWOD value is R13, with a measurement of 4932 kJ/m3. • The choice of working fluid is an important consideration in the design of both Rankine and Brayton cycles. • 143 different working fluids have been analyzed for Rankine and Brayton cycles in terms of performance characteristics. • This article aims to determine the ten best among different business fluids according to the determined criteria using TOPSIS. • Artificial Neural Network method is employed to identify the optimal working fluid. • TOPSIS and ANN methods can be used in thermodynamic analysis to find the best working fluids for the performance. [ABSTRACT FROM AUTHOR]