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Evaluations were conducted on the thermal performance of an organic Rankine cycle (ORC) system using three fluids as the evaporative system at a low‐grade heat source. The modified ORC evaporators were replaced with a three‐fluid system, which included hot fluids at the top and bottom and an isopentane working fluid in the middle section. Furthermore, the thermal performance assessment with a hot fluid heat transfer ratio in the outer and inner tubes (Q2/Q1) varying from 25:75 to 75:25 has been investigated. The impact of the hot fluid's (Q2/Q1) heat transfer ratios to saturated steam on the modified ORC's thermal performance assessment was examined, with an evaporative temperature range of 45–65°C and a pinch point temperature difference (PPTD) of 3–10°C. The Taguchi technique solves multiparameter optimization using the L9 orthogonal array. The findings showed that in three‐fluid‐based modified ORC systems, the network output, exergetic efficiency, and irreversibility went down with PPTD for all three Q2/Q1 cases. For Q2/Q1 of 75:25, the ORC's energetic efficiency and overall irreversibility reached their optimum, while a PPTD of 3–10°C reduced the exergetic efficiency by 19.71%. Also, Q2/Q1 of 75:25 showed the highest and 200% higher ORC system work done at PPTD of 3°C than Q2/Q1 of 25:75—the lowest. Modified ORC network generation, energy output, and heat transfer rate showed excellent results at an evaporative temperature of 58.33°C. For optimal network productivity, Q2/Q1 of 75:25 was 160% and 40% greater than 50:50 and 25:75 at 58.33°C, respectively. The three‐fluid‐based modified ORC system performs better with a 75:25 Q2/Q1 ratio. According to Taguchi's analysis, evaporation temperature affects the improved ORC system's thermal, exergy, and network generation. Also, heat transfer ratios (F = Q2/Q1) largely affect system irreversibility. [ABSTRACT FROM AUTHOR]

The essential element of human existence is energy. However, conventional energy sources are steadily running out, and it is necessary to create an energy-efficient renewable power generation system. In the present work, an organic Rankine flash cycle (ORFC) was implemented in a conventional solar power tower (SPT)-helium Brayton cycle (HBC) to generate extra power, enhancing efficiency. The performance of the proposed SPT-based power generation system (SPT-HBC-ORFC) was analyzed based on thermodynamic and economic aspects using computational techniques through engineering equation solver software. The results revealed that the proposed power plant's energy efficiency, exergy efficiency, power output, and total cost rate were 33.68%, 33.70%, 33.69%, and 15.47%, respectively, higher than those of a conventional SPT-HBC system at the given conditions. With 39% of all exergy destruction, heliostats are the source of the greatest exergy destruction. Parametric analysis reveals that solar subsection parameters had a larger effect on the performance of the proposed power plant. Comparisons with previous studies show that the present power generation system is more efficient than the SPT-based supercritical CO2 Brayton and Rankine cycles. [ABSTRACT FROM AUTHOR]

ABSTRACT The organic Rankine cycle (ORC) serves as an effective means of converting low‐grade heat sources into power, playing a pivotal role in environmentally friendly production and energy recovery. However, the inherent complexity, strong and unidentified nonlinearity, and control constraints pose significant challenges to designing an optimal controller for ORC systems. To address these issues, this research introduces a novel modeling and control framework for ORC systems. Leveraging an attention mechanism‐based long short‐term memory (AM‐LSTM) network, the dynamic characteristics of ORC systems, which are subject to non‐Gaussian disturbances, are accurately modeled. A performance metric based on survival information potential (SIP) is developed to optimize the network parameters. Furthermore, a multi‐objective optimization approach that integrates nonlinear model predictive control (NMPC) with the multiverse optimizer (MVO) algorithm is implemented to ensure effective control under varying operating conditions and constraints. Through extensive simulations, the proposed framework demonstrates superior accuracy, robustness, and control performance for ORC systems. [ABSTRACT FROM AUTHOR]

This study proposes a system to store waste heat as liquid hydrogen using a proton exchange membrane electrolyzer (PEME) and a mixed refrigerant hydrogen liquefaction cycle. The novelty of this study lies in proposing a waste heat recovery system that stores electricity as liquid hydrogen, consuming less power due to the improved exergy efficiency of the components. The proposed system is analyzed to achieve better efficiency in terms of thermal and exergy efficiencies. Waste heat is used to generate power by an organic Rankin cycle (ORC), produced electricity is utilized in the PEME unit and compressors of liquefaction cycle to produce and liquefy hydrogen, respectively. Codes are written in EES software to simulate the system. Thermodynamic analysis is done in order to achieve better thermal efficiency for the proposed model. Membrane potential at different values of current density is calculated and compared with validate the simulated model. The exergy efficiency of the liquid hydrogen production process is 57%. The exergy efficiency, rate of power produced in ORC, and rate of hydrogen production by the electrolyzer increase significantly by increasing the isentropic efficiency of the turbine. At a temperature of 340 K for the evaporator, the thermal efficiency of ORC is obtained at 8.5%, which is approximately 3% higher compared with that of the previous similar process. [ABSTRACT FROM AUTHOR]

This research examines the development of a turbine for a supercritical organic Rankine cycle (ORC) power generation system. The study details the design, manufacturing, and performance evaluation of a 100 kWe-class power generation turbine equipped with a magnetic bearing. Furthermore, a supercritical ORC power-generation system is constructed to evaluate the turbine performance. The turbine featured an overall expansion ratio of 9 with a two-stage centrifugal design, and it was integrated with the generator and magnetic bearings within a unified sealed-type casing. To ensure continuous electric power generation, internal turbine cooling devices were installed, and the evaporator connection pipes are modified. The performance tests demonstrate that the turbine produces 100 kW of electric power with an efficiency rate of 75 %. Comparison between the test results and numerical analysis confirms their good agreement. This research elucidates the considerations essential for the development of supercritical ORC turbines. [ABSTRACT FROM AUTHOR]

Liquefied natural gas (LNG) regasification terminals have specification that necessitates adjustment of heating value of LNG feed. One strategy to reduce heating value is to separate heavier hydrocarbons from LNG by utilizing LNG cold energy. The amount of cold energy utilized in recovering heavy hydrocarbon is much less resulting in wastage of remaining cold energy. To reverse this wastage, we propose a polygeneration process that encompasses an organic Rankine cycle to generate electricity and refrigeration for cold storage warehouse cooling and data center cooling by utilizing remaining cold energy. Based on process simulation and optimization, we found that a significant amount of cold energy is utilized resulting in an avoided CO2 emission, thereby enhancing sustainability of an LNG regasification terminal. [ABSTRACT FROM AUTHOR]

Blanching plays a critical role in food production, and it is imperative to explore innovative techniques to overcome the limitations associated with conventional blanching methods. This study investigates the application of vacuum-steam pulse blanching (VSPB), an emerging technology, in the blanching of potatoes, comparing it to traditional steam blanching (SB). The evaluation was based on the potatoes' browning enzyme inactivation, total phenols, antioxidation activity, starch digestibility, gelatinization degrees, and structural characteristics. The thermal and morphological analyses revealed that the blanching duration required for the browning enzyme inactivation totally gelatinized the potato starches. Prolonged blanching, whether using VSPB (with extended steaming cycles or lower vacuum pressure) or SB (for 180 seconds), decreased starch crystallinity and enhanced digestibility. VSPB effectively inactivated the browning enzyme while preserving total phenols and antioxidation activity in potatoes, yielding 39.14 mg GAE/100g fresh potato and 182.60 µmol TE/100 g fresh potato, respectively. In contrast, continuous steaming during SB for 60 s led to high enzyme activity, color difference, browning index, and FTIR absorption, reducing total phenols and antioxidant activity levels. Under optimum conditions (20 kPa vacuum pressure, three cycles, and 20 s steaming duration), VSPB increased the total phenol content and antioxidation activity, retained the potato structure and crystallinity, and recorded the lowest infrared absorbance level, providing an efficient scenario for potato blanching. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogen, Fuel Cell & Energy Storage is the property of Iranian Research Organization for Science & Technology (IROST) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Recent research suggests that the implementation of more efficient combined cooling and power systems, which enable the cogeneration of electricity and cooling, can enhance the efficiency of hybrid plants. The present investigation is motivated by finding that, in the literature review on combined power and cooling systems, there is very limited information on the coupling of the organic Rankine cycle (ORC) and the ejector refrigeration cycle (ERC) with low sink temperatures. A suggested approach to do this involves using hot exhaust gas and waste heat engines to power an ORC hybrid system. To enhance the ORC–ERC system's performance, three heater configurations use waste heat from the ORC turbine exhaust, ejector, and engine waste heat to heat the working fluid. Renewable energy sources are the primary focus of most current research initiatives. The present research focuses on unique ORC and ERC systems, considered as combined power and cooling systems, with the goal of improving exergy performance at low temperatures. The suggested ORC–ERC can generate energy destruction of 69.85 kW at a source temperature of 155 °C, with an exergetic efficiency of 76.9% at the turbine. Setting the entrainment ratio at 0.5 results in a total sum unit cost of products (SUCP) of 465 $/kW‐h for the ORC–ERC. Furthermore, the 37.83% exergy destruction ratio introduces heat exchanger 2 (HE2) as the primary cause of the suggested ORC–ERC's irreversibility. A detailed parametric study reveals that altering the hot source temperature and entrainment ratio improves the system's SUCP. The current examination at high sink temperatures may be expanded to an advanced exergoenvironmental investigation. [ABSTRACT FROM AUTHOR]

A novel dual-pressure organic Rankine cycle system (DPORC) with a dual-stage ejector (DE-DPORC) is proposed. The system incorporates a dual-stage ejector that utilizes a small amount of extraction steam from the high-pressure expander to pressurize a large quantity of exhaust gas to perform work for the low-pressure expander. This innovative approach addresses condensing pressure limitations, reduces power consumption during pressurization, minimizes heat loss, and enhances the utilization efficiency of waste heat steam. A thermodynamic model is developed with net output work, thermal efficiency, and exergy efficiency (Wnet, ηt, ηex) as evaluation criteria, an economic model is established with levelized energy cost (LEC) as evaluation index, an environmental model is created with annual equivalent carbon dioxide emission reduction (AER) as evaluation parameter. A comprehensive analysis is conducted on the impact of heat source temperature (TS,in), evaporation temperature(T2), entrainment ratio (Er1, Er2), and working fluid pressure (P5, P6) on system performance. It compares the comprehensive performance of the DE-DPORC system with that of the DPORC system at TS,in of 433.15 K and T2 of 378.15 K. Furthermore, multi-objective optimization using the dragonfly algorithm is performed to determine optimal working conditions for the DE-DPORC system through the TOPSIS method. The findings indicate that the DE-DPORC system exhibits a 5.34% increase in Wnet and ηex, a 58.06% increase in ηt, a 5.61% increase in AER, and a reduction of 47.67% and 13.51% in the heat dissipation of the condenser and LEC, compared to the DPORC system, highlighting the advantages of this enhanced system. The optimal operating conditions are TS,in = 426.74 K, T2 = 389.37 K, Er1 = 1.33, Er2 = 3.17, P5 = 0.39 MPa, P6 = 1.32 MPa, which offer valuable technical support for engineering applications; however, they are approaching the peak thermodynamic and environmental performance while falling short of the highest economic performance. [ABSTRACT FROM AUTHOR]

Electrolysis of water for hydrogen-production has enormous potential. This study proposes a semi-closed Rankine cycle for efficiently utilizing direct hydrogen combustion via thermal power conversion. Unlike traditional closed Rankine cycles, combustion occurs inside the combustion chamber with hydrogen and pure oxygen, followed by a mixed heat exchange with the mainstream working fluid, water. The heat absorption process of the semi-closed Rankine cycle occurs within the working fluid and exhibits characteristics of both open and closed cycles. Thus, this cycle can combine the advantages of desirable parameters and isothermal heat rejection of the Rankine cycle. Applying the semi-closed Rankine cycle to hydrogen fuel utilization yields a higher energy efficiency, especially when coupled with a supercritical compression regeneration process. The main steam parameters were 620 °C/30 MPa, the cycle's average heat absorption temperature reached 561 °C, and its energy efficiency was 59.35%. When the main steam parameters were increased to 1200 °C/30 MPa, the average heat absorption temperature rose to 1021 °C and its energy efficiency was 68.27%, demonstrating a significant efficiency advantage. The newly proposed semi-closed Rankine cycle based on direct combustion of hydrogen fuel provides a novel and feasible path for exploring the efficient utilization of hydrogen. • The semi-closed Rankine cycle is proposed, which is suitable for direct combustion of hydrogen fuel. • The direct combustion characteristic significantly increases the main steam temperature of the cycle. • Supercritical compression regeneration process significantly increases the cycle's energy efficiency. • The cycle achieves efficient utilization of hydrogen in the thermal power conversion field. [ABSTRACT FROM AUTHOR]

In light of the intensifying global climate crisis and the increasing demand for efficient electricity and cooling systems, the exploration of advanced power generation technologies has become crucial. This paper presents a comprehensive analysis of Organic Rankine Cycle–Vapor Compression Cycle (ORC-VCC) systems utilizing low-grade waste heat for the dual purpose of electricity and cooling production. The study focuses on systems that harness waste heat below 90 °C with thermal inputs up to 500 kW. An in-house Python code was developed to calculate cycle parameters and perform multi-objective optimization targeting the maximization of both ORC-VCC efficiency and power output. The optimization was conducted for 10 different cases by evaluating five working fluids across two different ambient temperatures. The analysis reveals that the optimized system achieved an impressive overall cycle efficiency exceeding 90%, demonstrating the significant potential of ORC-VCC technology in waste heat recovery applications. The Non-Dominated Sorting Genetic Algorithm II (NSGA-II) multi-objective optimization approach was found to be particularly effective at navigating the multi-dimensional solution space and identifying the global optimum. This study provides valuable insights into system performance across a range of operating conditions and design parameters. Sensitivity analyses highlight key factors influencing cycle efficiency and power output. These findings have important implications for the development and deployment of ORC-VCC systems as a sustainable and efficient solution to meet growing energy needs while reducing greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

Today, most of the world's electric energy is generated by burning hydrocarbon fuels, which causes significant emissions of harmful substances into the atmosphere by thermal power plants. In world practice, flue gas cleaning systems for removing nitrogen oxides, sulfur, and ash are successfully used at power facilities but reducing carbon dioxide emissions at thermal power plants is still difficult for technical and economic reasons. Thus, the introduction of carbon dioxide capture systems at modern power plants is accompanied by a decrease in net efficiency by 8–12%, which determines the high relevance of developing methods for increasing the energy efficiency of modern environmentally friendly power units. This paper presents the results of the development and study of the process flow charts of binary and trinary combined-cycle gas turbines with minimal emissions of harmful substances into the atmosphere. This research revealed that the net efficiency rate of a binary CCGT with integrated post-combustion technology capture is 39.10%; for a binary CCGT with integrated pre-combustion technology capture it is 40.26%; a trinary CCGT with integrated post-combustion technology capture is 40.35%; and for a trinary combined-cycle gas turbine with integrated pre-combustion technology capture it is 41.62%. The highest efficiency of a trinary CCGT with integrated pre-combustion technology capture is due to a reduction in the energy costs for carbon dioxide capture by 5.67 MW—compared to combined-cycle plants with integrated post-combustion technology capture—as well as an increase in the efficiency of the steam–water circuit of the combined-cycle plant by 3.09% relative to binary cycles. [ABSTRACT FROM AUTHOR]

Decarbonizing heat-intensive industries by reusing the waste heat for power or combined heat and power systems is becoming increasingly important to address global warming. The Organic Rankine Cycle has shown a high level of feasibility and performed efficiently for utilizing medium-to-low-grade heat from renewable resources and heat-intensive industries for direct power generation. This study contributes to the field by conducting a techno-economic investigation of various Organic Rankine Cycle configurations to enhance energy conversion when real-life transient waste heat sources are available. These configurations were optimized to maximize energy output along with economic benefits. The non-linear programming by quadratic Lagrangian, a computational unintensive yet accurate optimization algorithm, was utilized for the multi-objective optimization. The optimized cycle configurations showed a 12.57% enhancement of turbine efficiency. Combining regeneration and recuperation enhanced the superheating by 32%, and the optimized air preheater cycle improved the overall objective by 64.2% compared to the pre-optimized conventional cycle, leading to a feasible 1.72-year payback period. [ABSTRACT FROM AUTHOR]

Strategy for energy development of Russia for the period up to 2035 provides for the participation of nuclear power plants with generation 3+ power units in regulating the daily unevenness of the electrical load, which forces the nuclear power plant to operate in an ineffective unloading mode. In order to solve this problem, a combination of nuclear power plants with a hydrogen complex is being considered, when during the hours of supposed unloading of the nuclear power plant due to the electrolysis of water, unclaimed power is converted into hydrogen and oxygen, and during peak load hours, hydrogen is burned in an oxygen environment in order to heat/overheat the working fluid in the steam turbine cycle Nuclear power plants and peak power generation. At the same time, the safety issues of using hydrogen when burned in oxygen are of great importance, which is, first of all, due to the inevitable presence of a certain amount of chemical underburning, which creates the risk of the formation of an explosive hydrogen-oxygen mixture along the working fluid path in the steam turbine cycle of a nuclear power plant. Based on the existing experience of the authors, a method for assessing the underburning of hydrogen and an indicator of the efficiency of recirculation in the proposed scheme using the recycling of unreacted hydrogen have been developed; a theoretical assessment of the underburning of hydrogen has been previously performed. In addition, a small-scale experimental installation has been developed that allows simulating the conditions of combustion of hydrogen in oxygen with recycling of unreacted hydrogen under the conditions of the steam turbine cycle of a nuclear power plant. This work represents a new approach to solving the problem of the safe use of hydrogen. The developed method makes it possible to determine specific concentrations of unreacted hydrogen depending on the flow rate and pressure in the flame tube. Based on the proposed indicator of recycling efficiency, it is shown that the proportion of hydrogen entrainment due to its low solubility in water is very small, which, at the accepted pressure and temperature of recycled unreacted hydrogen, determines a sufficiently high indicator of recycling efficiency. As a preliminary theoretical assessment has shown, the magnitude of the recirculation efficiency depends on the pressure and temperature at which unreacted hydrogen is recycled, which will obviously require further assessments over a wider range of pressures and temperatures. The proposed experimental methodology will make it possible to perform a reasonable assessment of the efficiency of recirculation of unreacted hydrogen for conditions of additional heating of feedwater in the steam turbine cycle of a nuclear power plant. [ABSTRACT FROM AUTHOR]

Reusing waste heat is one of the techniques for increasing energy efficiency, which is a highly emphasized issue today. The organic Rankine cycle, also known as ORC, is increasingly recognized as a promising technique for converting low-temperature heat into electricity. ORCs are designed to operate without human intervention and require minimal maintenance. Although basic ORC is increasingly accepted by the industry, there is still a need to improve cost effectiveness. For the purpose of this review, calculations of the ORC system were made for the purpose of generating electricity by utilizing the recovery of heat energy at low temperatures for companies that discharge waste heat into the environment. EES program was used to investigate the relationship between efficiency rates as well as fluid properties to be used in the ORC system. Among the various fluids used in this system, cyclohexane, R123 and R290 were determined to have the highest efficiency rates. Estimated efficiencies for these fluids are 26%, 18.28% and 8% respectively. Condenser and turbine powers were calculated and compared to determine which fluid had the optimum efficiency rate and waste heat capacity. It has been noted that as the temperature of the condenser increases, the power output of the turbine decreases. The most effective fluids for turbine power generation are cyclohexane and R123. [ABSTRACT FROM AUTHOR]

Limited experimental research has been conducted on organic Rankine cycle (ORC) systems that use wet working fluids. Therefore, the present study examined how the performance of an ORC system that uses a wet working fluid (R134a) was affected by the superheat degree ratio (SDR) under various scroll rotation speeds. The SDR is the dimensionless ratio between superheat degree and evaporation temperature at a given heat source temperature. Experimental results indicated that at scroll rotation speeds of 900, 1350, and 1800 rpm, the maximum output power of the aforementioned system was 1103, 1464, and 1537 W, respectively, with SDRs of 0.49, 0.49, and 0.54, respectively. The maximum net efficiencies at these speeds were 5.87%, 5.91%, and 5.32%, respectively, which occurred at SDRs of 0.61, 0.49, and 0.48, respectively. This level of system performance was attributable to the high enthalpy at the expander inlet and the high mass flow rate at the high evaporation pressure under an SDR of approximately 0.5. Although increasing the SDR did not enhance the scroll expander's isentropic efficiency, this efficiency decreased considerably when the SDR fell below 0.2. These findings emphasize the importance of optimizing the SDR of ORC systems to improve their performance. [ABSTRACT FROM AUTHOR]

The increasing global demand for energy-efficient cooling systems, combined with the need to reduce greenhouse gas emissions, has led to growing interest in using low-GWP (global warming potential) refrigerants. This study conducts a multi-objective optimization of a small-scale organic Rankine cycle–vapor compression cycle (ORC-VCC) system, utilizing refrigerants R1233zd, R1244yd, and R1336mzz, both individually and in combination within ORC and VCC systems. The optimization was performed for nine distinct cases, with the goals of maximizing the coefficient of performance (COP), maximizing cooling power, and minimizing the pressure ratio in the compressor to enhance efficiency, cooling capacity, and mechanical reliability. The optimization employed the Non-dominated Sorting Genetic Algorithm III (NSGA-III), a robust multi-objective optimization technique that is well-suited for exploring complex, non-linear solution spaces. This approach effectively navigated trade-offs between competing objectives and identified optimal system configurations. Using this multi-objective approach, the system achieved a COP of 0.57, a pressure ratio around 3, and a cooling capacity exceeding 33 kW under the specified boundary conditions, leading to improved mechanical reliability, system simplicity, and longevity. Additionally, the system was optimized for operation with a cooling water temperature of 25 °C, reflecting realistic conditions for contemporary cooling applications. [ABSTRACT FROM AUTHOR]

Cold energy generation is an important part of liquefied natural gas (LNG) cold energy cascade utilization, and existing studies lack a specific descriptive model for LNG cold energy transmission to the AC subgrid. Therefore, this paper proposes a descriptive model for the grid-connected process of cold energy generation at LNG stations. First, the expansion kinetic energy transfer of the intermediate work mass is derived and analyzed in the LNG unipolar Rankine cycle structure, the mathematical relationship between the turbine output mechanical power and the variation in the work mass flow rate and pressure is established, and the variations in the LNG heat exchanger temperature difference, seawater flow rate, and the turbine temperature difference in the cycle system are investigated. Secondly, based on the fifth-order equation of state of the synchronous generator, the expressions of its electromagnetic power, output AC frequency, and voltage were analyzed. Finally, the average equivalent models of the machine-side and grid-side converters are established using a direct-fed grid-connected structure, thus forming a descriptive model of the overall drive process. The ORC model is built in Aspen HYSIS to obtain the time series expression of the torque output of the turbine; based on the ORC output torque, the permanent magnet synchronous generator (PMGSG) as well as the direct-fed grid-connected structure are built in MATLAB/Simulink, and the active power and current outputs of the grid-following-type voltage vector control method and the grid-forming-type power-angle synchronous control method are also verified. [ABSTRACT FROM AUTHOR]

Copyright of Low-Carbon Chemistry & Chemical Engineering is the property of Low-Carbon Chemistry & Chemical Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The combination of renewable energy and liquefied natural gas (LNG) cold energy can effectively improve energy utilization efficiency and achieve the goal of energy conservation and emission reduction, which is one of the important directions of future development. This work proposed a cascade organic Rankine cycle (ORC) driven by a geothermal heat source and an LNG heat sink. Seven organic fluids are chosen as candidates to form different working fluid pairs. The effects of the main design parameters on system performance are carried out through the thermodynamic analysis. Then, the optimal design conditions and fluid selection schemes are searched based on the single-objective optimization results. Finally, the exergy destruction study is conducted under the optimal design conditions and working fluid pair. Results showed that the cascade ORC system using the working fluid pair of R601/R290 had the highest exergy efficiency, which could reach 20.02%. At the same time, under the optimal design conditions, the secondary cycle condenser and LNG direct expansion brought high exergy destruction, which was respectively 29.3% and 25.8%, and followed by the two turbines in the cascade ORC system, which were 16.1%, 11.2% and 7.7%. [ABSTRACT FROM AUTHOR]

The organic Rankine cycle (ORC) is an effective way for engine waste heat recover (WHR). The selection of the working fluid is crucial. In recent years, low GWP and ODP working fluid have been invented. For R123, which is commonly used in engine ORC-WHR system, the alternative working fluid is R1233zd(E). In order to explore the performance of R123 and R1233zd(E) when applied to ORC-WHR system, this study conducted experimental studies of R123 and R1233zd(E) under a wide range of engine working conditions. The experiments were carried out under seven sets of engine working conditions with gradually increasing loads. Variable operating parameter experiments were carried out for R123 and R1233zd(E) at each engine load. The selected operating parameters include expander speed and superheat degree. The experimental results show that R123 has higher output power and thermal efficiency compared to R1233zd(E) at all engine conditions.The maximum output power and thermal efficiency of R123 are 1.55 kw and 5.81% respectively.The maximum output power and thermal efficiency of R1233zd(E) are 1.43 kw and 5.29% respectively. Taking the net output power as the evaluation index, the optimal expander speed of R123 is higher than that of R1233zd(E) under the same engine working condition, and the superheat degree has little effect on the net output power. [ABSTRACT FROM AUTHOR]

To better reduce the carbon emissions of a park-integrated energy system (PIES), optimize the comprehensive operating cost, and smooth the load curve, a source-load flexible response model based on the comprehensive evaluation index is proposed. Firstly, a source-load flexible response model is proposed under the stepped carbon trading mechanism; the organic Rankine cycle is introduced into the source-side to construct a flexible response model with traditional combined heat and power (CHP) unit and electric boiler to realize the flexible response of CHP to load; and the load-side categorizes loads into transferable, interruptible, and substitutable loads according to the load characteristics and establishes a comprehensive demand response model. Secondly, the analytic network process (ANP) considers the linkages between indicators and allows decision-makers to consider the interactions of elements in a complex dynamic system, resulting in more realistic indicator assignment values. Considering the economy, energy efficiency, and environment, the PIES optimization operation model based on the ANP comprehensive evaluation index is constructed to optimize the system operation comprehensively. Finally, the CPLEX solver in MATLAB was employed to solve the problem. The results of the example show that the source-load flexible response model proposed in this paper reduces the operating cost of the system by 29.90%, improves the comprehensive utilization rate by 15.00%, and reduces the carbon emission by 26.98%, which effectively enhances the system's economy and low carbon, and the comprehensive evaluation index based on the ANP reaches 0.95, which takes into account the economy, energy efficiency, and the environment, and is more superior than the single evaluation index. [ABSTRACT FROM AUTHOR]

To meet the escalating electricity demand and rising fuel costs, along with notable losses in power transmission, exploring alternative solutions is imperative. Gas turbines demonstrate high efficiency under ideal International Organization for Standardization (ISO) conditions but face challenges during summer when ambient temperatures reach 40°C. To enhance performance, the proposal suggests cooling inlet air by 15°C using a vapor absorption chiller (VAC), utilizing residual exhaust gases from a combined cycle power plant (CCPP) to maximize power output. Additionally, diverting a portion of exhaust gases to drive an organic Rankine cycle (ORC) for supplementary power generation offers added efficiency. This integrated approach not only boosts power output but also minimizes environmental impact by repurposing exhaust gases for additional operations. This study presents a detailed energy and economic analysis of a modified combine cycle power plant, in Kotri, Pakistan. R600A is used as organic fuel for the ORC while LiBr-H2O solution is used for the VAC. Two performance parameters, efficiency and energy utilization factor, Four energetic parameters, Work output of ORC, modified CCPP, original CCPP and cooling rate, and one economics parameter, payback period were examined under varying ambient conditions and mass fraction of exhaust gases from outlet of a gas turbine (ψ). A parametric investigation was conducted within the temperature range of 18°C to 50°C, relative humidity between 70% and 90%, and the ψ ranging from 0 to 0.3. The findings reveal that under elevated ambient conditions (40°C, 90% humidity) with ψ at 0, the Energy Utilization Factor (EUF) exceeds 60%. However, the ORC exhibits a low work output of 100 KW alongside a high cooling load of 29,000 kW. Conversely, the modified system demonstrates an augmented work output of approximately 81,850 KW compared to the original system's 78,500 KW. Furthermore, the integration of this system proves advantageous across all metrics. Additionally, the payback period of the system is contingent on ambient conditions, with lower conditions correlating to shorter payback periods and vice versa. [ABSTRACT FROM AUTHOR]

To alleviate thermal mismatch problem of environmental barrier coatings (EBCs) on SiC fiber‐reinforced SiC ceramic matrix composites (SiCf/SiC CMCs) surface and improve their high‐temperature durability for aircraft engines, by fully utilizing the appropriate thermal expansion coefficient, low oxygen transmittance, low thermal conductivity, and other advantages of ytterbium aluminum garnet (Yb3Al5O12), the double ceramic layered Yb3Al5O12/Yb2Si2O7 (DCL‐Yb3Al5O12) and the triple ceramic layered Yb3Al5O12/Yb2SiO5/Yb2Si2O7 (TCL‐Yb3Al5O12) EBC systems were prepared on SiCf/SiC CMCs by atmospheric plasma spraying (APS). Their phase composition and microstructures were investigated comparatively. The thermal cycling and water vapor/oxygen corrosion behavior of these coating systems were compared at 1300°C. The results showed that the thermal cycling life of the DCL‐Yb3Al5O12 and TCL‐Yb3Al5O12 EBC systems were 295 and 320 times, respectively. The failure of both the coating systems occurred between the Yb2Si2O7 layer and Si bond coat. The strength retention rate of DCL‐Yb3Al5O12 and TCL‐Yb3Al5O12 EBC systems after water vapor/oxygen corrosion for 70 h was 12.8% and 23.1%, respectively, and the fracture modes of both the systems exhibited "pseudoplastic" characteristic. TCL‐Yb3Al5O12 EBC systems with a gradient structure of more layers exhibit more excellent high‐temperature durability than DCL‐Yb3Al5O12 EBCs. [ABSTRACT FROM AUTHOR]

Considering the importance of using systems with high productivity, in order to reduce fuel consumption and economic savings, multiple production systems can be an attractive option. In this study, a simultaneous production system of power, steam and hydrogen based on molten carbonate fuel cell with methane fuel source is presented. The proposed system consists of four main parts, molten carbonate fuel cell, heat recovery steam generator, proton exchange membrane electrolyzer, and organic Rankine cycle. The system is evaluated from viewpoints of energy, exergy and exergeoeconomics. In the organic Rankine cycle, R141b has the best performance in terms of electricity production, organic fluid consumption, and efficiency among the proposed organic fluids, so that with R141b the efficiency reaches to 18.31%. Also, 68.85% of heat recovery is done by the heat recovery steam generator and the rest is done by the heat recovery vapor generator. The energy, exergy, and electrical efficiencies of the proposed system are 64.29, 63.53, and 39.69%, respectively, which shows a good performance compared to many power plants. The highest exergy destruction occurs in the air heat exchanger with 45673 kW. The operating cost rate of the system is 2.38 $/s and the hydrogen production rate is 3.67 kg/h. • 3E analyses are performed for the combined system of power, steam, and hydrogen production. • 68.8% of the heat recovery is done in the HRSG and the rest in the ORC. • Energy and exergy efficiencies are 64.4% and 57.7%, respectively. • The best organic fluid from a 3E perspective is R141b. [ABSTRACT FROM AUTHOR]

An assessment was made of the influence of underburning of hydrogen in a hydrogen-oxygen steam generator on the technical and economic efficiency of installing a hydrogen energy complex at a nuclear power plant, which is a well-known approach to solving an urgent problem of modern energy systems – ensuring the further development of nuclear energy as an environmentally friendly source of electricity based on the accumulation of off-peak electricity. An approach is considered and a diagram is presented for increasing the reliability of using the hydrogen energy complex at nuclear power plants by reducing underburning and eliminating the entry of unburned hydrogen into the main steam power cycle of the power unit. Several options for the level of hydrogen underburning and a range of system operating conditions for the hydrogen energy complex are considered. A comprehensive calculation of the technical and economic indicators of the hydrogen energy complex at nuclear power plants was carried out, and the conditions for its effectiveness were determined. As calculations have shown, underburning of hydrogen leads to a noticeable decrease in annual income and average annual profit from the sale of peak electricity. The achieved reduction is 11.67 and 35.01 million rubles/year at 5 and 15% hydrogen underburning, respectively. At the minimum tariff for off-peak electricity, the reduction in accumulated net present value is 96.6, 192.8 and 289.4 with an increase in hydrogen underburning to 5, 10 and 15%, respectively. The dependence of the marginal level of hydrogen underburning on the tariff for off-peak electricity, which ensures the efficiency of implementation of the considered hydrogen energy complex at nuclear power plants, is constructed. As calculations have shown, efficient operation of the hydrogen energy complex is achieved at a tariff for off-peak energy in the range from 0 to 0.45, 0.38, 0.3 and 0.24 rubles/kWh with hydrogen underburning of 0, 5, 10 and 15%, respectively. [ABSTRACT FROM AUTHOR]

The study investigated the efficiency improvement of a 9.5 MW gas engine‐based combined cycle power plant utilizing multiple waste heat streams in an organic Rankine cycle. Four different waste heat sources were considered: I) boiler stack gas, II) engine jacket water, III) boiler steam, and IV) engines' exhaust gas. Besides, three different organic fluids; R245fa, R134a, and R1234ze(Z) were employed to find the best working fluid in the given operating conditions. The performance analysis of the ORC revealed that R245fa is a suitable potential fluid for cases I and II, whereas R134a performs better for cases III and IV. Integrating the ORC with the boiler stack using R245fa at 8 barg provided an additional 16.5% waste gas heat recovery. It increased the net electric efficiency of the existing plant by 0.7%. The jacket water heat recovery further improved the net electric efficiency by 2.1%. By integrating both streams with the ORC in the existing system, the net electrical efficiency was increased from 42.6% to 45.3%. The estimated payback period for the jacket water heat recovery scenario utilizing Chinese ORC equipment was 9.3 years. However, this period was significantly reduced to 4.6 years for general industry applications, rendering it economically viable. [ABSTRACT FROM AUTHOR]

Waste incineration has become the main treatment method for urban household waste, and it can produce a large amount of electricity. The efficiency of waste incineration plants is reduced due to the large amount of waste heat carried away by the flue gas. Recycling and utilizing the waste heat from flue gas are important in improving the economic benefits of waste incineration, which is necessary for energy conservation and emission reduction. Based on the principle of cascade waste heat recovery from waste incineration flue gas whilst considering system safety and efficiency, this study proposed a new combination cascade waste heat recovery system consisting of a Rankine cycle, an organic Rankine cycle and a heat pump cycle. Thermodynamic and economic analyses of the combined system were conducted in detail. The results indicated that the energy efficiency of the combined system could reach up to 73%. The maximum net present value of the system was million USD 1.59 million, and the dynamic investment payback period was about 6.5 years. The isentropic efficiency of the combined system's pumps and turbines had a significant impact on the system's performance. A higher isentropic efficiency resulted in better system performance. The exergy analysis showed that the evaporator of the heat pump system had the highest irreversible loss. [ABSTRACT FROM AUTHOR]

Due to its simple structure and stable operation, the Organic Rankine Cycle (ORC) has gained significant attention as a primary solution for low-grade thermal power generation. However, the economic challenges associated with development difficulties in hot dry rock (HDR) geothermal power systems have necessitated a better balance between performance and cost effectiveness within ORC systems. This paper establishes a game pattern of the Organic Rankine Cycle with performance as the master layer and economy as the slave layer, based on the Stackelberg game theory. The optimal working fluid for the ORC is identified as R600. At the R600 mass flow rate of 50 kg/s, the net system cycle work is 4186 kW, the generation efficiency is 14.52%, and the levelized cost of energy is 0.0176 USD/kWh. The research establishes an optimization method for the Organic Rankine Cycle based on the Stackelberg game framework, where the network of the system is the primary optimization objective, and the heat transfer areas of the evaporator and condenser serve as the secondary optimization objective. An iterative solving method is utilized to achieve equilibrium between the performance and economy of the ORC system. The proposed method is validated through a case study utilizing hot dry rock data from Qinghai Gonghe, allowing for a thorough analysis of the working fluid and system parameters. The findings indicate that the proposed approach effectively balances ORC performance with economic considerations, thereby enhancing the overall revenue of the HDR power system. [ABSTRACT FROM AUTHOR]

Both steam and hot water flooding of high-viscosity oils in the presence of swelling clays are difficult methods for producing oil efficiently because of potential formation permeability reduction. This paper pertains to heavy oil recovery from the East Moldabek formation where the oil API gravity is about 22 and is inundated with swelling clays. To achieve this, we used the IntersectTM reservoir simulator to compare oil recovery economics using both hot water and steam injection as a function of steam cycle duration, temperature, and steam dryness. We also studied clay swelling in the East Moldabek formation where clay poses a significant challenge due to its impact on permeability reduction. In this research, we developed an equation based on experimental data to establish a relationship between water mineralization and permeability in the East Moldabek formation. The equation provides valuable insight on how to mitigate clay swelling which is crucial for enhancing oil recovery efficiency—especially in sandstone reservoirs. Our modeling studies provide the recovery efficiencies for salinities of the hot water EOR versus cyclic steam EOR methods in a formation containing swelling clays. Specifically, the reduction in formation permeability as a function of the distilled water fraction is the controlling parameter in hot water or steam flooding—when the formation water mixture becomes less saline, oil recovery decreases. Our research shows that clay swelling can significantly impact cyclic steam stimulation outcomes, potentially reducing its effectiveness, while hot water flooding may offer a more cost-effective and operationally feasible solution in formations where clay swelling is a concern. Economic analysis reveals the potential for achieving an optimal favorable condition for hot water injection. Therefore, this paper provides a guideline on how to conduct thermal oil recovery for heavy oils in fields with high clay content such as the East Moldabek deposit. [ABSTRACT FROM AUTHOR]

This paper presents an analysis and optimization of a polygeneration power-production system that integrates a concentrating solar tower, a supercritical CO2 Brayton cycle, a double-flash geothermal Rankine cycle, and an internal combustion engine. The concentrating solar tower is analyzed under the weather conditions of the Mexicali Valley, Mexico, optimizing the incident radiation on the receiver and its size, the tower height, and the number of heliostats and their distribution. The integrated polygeneration system is studied by first and second law analyses, and its optimization is also developed. Results show that the optimal parameters for the solar field are a solar flux of 549.2 kW/m2, a height tower of 73.71 m, an external receiver of 1.86 m height with a 6.91 m diameter, and a total of 1116 heliostats of 6 m × 6 m. For the integrated polygeneration system, the optimal values of the variables considered are 1437 kPa and 351.2 kPa for the separation pressures of both flash chambers, 753 °C for the gasification temperature, 741.1 °C for the inlet temperature to the turbine, 2.5 and 1.503 for the turbine pressure ratios, 0.5964 for the air–biomass equivalence ratio, and 0.5881 for the CO2 mass flow splitting fraction. Finally, for the optimal system, the thermal efficiency is 38.8%, and the exergetic efficiency is 30.9%. [ABSTRACT FROM AUTHOR]

The present study focuses on the recovery of waste heat in an autonomous safety system designed for advanced nuclear reactors. The system primarily relies on passive safety condensers, which are increasingly integrated into the design of advanced Pressurized Water Reactors (PWRs). These condensers are typically immersed in large water tanks that serve as heat sinks and are placed at sufficient heights to ensure natural circulation. Such a heat removal system can operate for an extended period, depending on the size of the tank. This research is driven by the potential to recover part of the energy stored in the boiling water volume, using it as a heat source for an Organic Rankine Cycle (ORC) system via an immersed heat exchanger. The electricity generated by the ORC engine can be used to power the system components, thereby making it self-sufficient. In particular, a pump replenishes the water tank, ensuring core cooling for a duration no longer limited by the water volume in the tank. An experimental test setup, including a boiling water pool and an ORC engine with an electrical output of approximately several hundred watts, along with an immersed evaporator, was constructed at CEA (Grenoble, France). Several test campaigns were conducted on the experimental test bench, exploring different configurations: two distinct ORC working fluids, cold source temperature variation effects, and relative positioning of the submerged evaporator and heat source within the water tank impact. These tests demonstrated the reliability of the system. The results were also used to validate both the ORC condenser and evaporator models. This article presents this innovative system, which has recently been patented. Moreover, to the best of our knowledge, the investigated configuration of an ORC that includes an immersed evaporator is original. [ABSTRACT FROM AUTHOR]

The objective of this paper is to assess the techno-economic performance of different cycle configurations for pumped thermal energy storage (PTES), including the effects of charging electricity costs. Reversible turbomachinery was employed to reduce the capital cost of the system. Brayton cycles with different working fluids and a subcritical Rankine cycle operating with ammonia were compared. Both liquid and packed bed thermal storages were investigated. A new cost correlation for turbomachines, initially established for the turbines of organic Rankine cycles, was developed for compressors and reversible machines. This correlation is based on the number of stages and physical size of the machine, which were estimated considering thermodynamic as well as mechanical limitations. The results indicate that for a plant size of 50 MW and a discharge duration of 8 h, the Brayton system with liquid storage and helium as a working fluid has the lowest levelized cost of storage at 0.138 $/kWh, mainly due to the high thermal conductivity of the fluid. Packed bed thermal energy storage systems were found to be more expensive than liquid storage systems due to the large cost of the pressure vessels, with cost parity reached at a discharge duration of 4 h. However, at this duration, lithium-ion batteries are likely to be cheaper. The results suggest that the levelized cost of storage for the Rankine cycle-based system is slightly higher at 0.151 $/kWh. [ABSTRACT FROM AUTHOR]

OBJECTIVE The objective of this study was to determine the effects of repeated steam sterilization cycles on the biomechanical properties of surgical screws. METHODS 42 3.5-mm and 42 2.0-mm self-tapping, cortical screws were divided into 3 groups per size and underwent autoclave sterilization for 1 (G1), 50 (G50), or 100 (G100) cycles and testing from August 2018 through June 2021. Sixty screws were then inserted into canine cadaver femurs, and biomechanical properties were measured, including peak insertional torque, torque to failure, and pullout strength, each normalized to cortical thickness. Scanning electron micrographs were taken from 24 screws, and images were blindly analyzed by 5 trained examiners. RESULTS The mean normalized insertion torque for 3.5-mm screws was significantly different between G1 and both G50 and G100. The mean normalized torque to failure for 3.5-mm screws was significantly different between G1 and both G50 and G100. Axial pullout testing was found to be significantly different for 2.0-mm screws between G1 and G100. Scanning electron micrographs surface scoring identified a significant difference in 3.5-mm screws at the screw tip. CONCLUSIONS The results indicate that biomechanical changes occur with repeated steam sterilizations. Specifically, peak insertional torque and torque to failure are decreased with increased sterilizations for 3.5-mm screws, whereas 2.0-mm screws were altered in pullout testing after 100 sterilizations. It is suspected that numerous sterilizations negatively alter the physical-mechanical properties of certain screw sizes. CLINICAL RELEVANCE The biomechanical properties of the bone-implant interface could negatively be affected by multiple steam sterilizations during clinical setting. [ABSTRACT FROM AUTHOR]

Organic Rankine cycle (ORC) has been considered as one of the most promising technologies in industrial waste heat utilization and power generation. During the actual operation of ORC system, due to the fluctuation of cooling and heat sources, the system operates under off-design conditions in most cases. In this paper, thermodynamic model, heat transfer process description and power equipment model are established to evaluate the operating parameters of ORC for the off-design conditions. Evaporation temperature and condensation temperature are taken as independent parameters for the operation of ORC system. Genetic algorithm is adopted to optimize the independent parameters under the maximum net output power. The results show that the effect of optimizing independent parameters is to make the working fluid at the outlet of the preheater as close as possible to a saturated liquid state, and the working fluid at the inlet of the screw expander should be in a saturated gas state. With the optimal power output increasing by 19.1% for every 5 °C increase in hot water inlet temperature, 9.2% for every 20 kg/s increase in hot water mass flow rate, and 3.9% for every 1 °C decrease in cooling water temperature. The optimization method of off-design operating conditions has good system performance and good engineering application prospects. [ABSTRACT FROM AUTHOR]

Copyright of Advances in New & Renewable Energy is the property of Editorial Office of Advances in New & Renewable Energy and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Because of its low concentration and low energy in an organic Rankine cycle (ORC) system, more than 50% of low-grade thermal energy with a temperature below 300 °C is not taken seriously. The relationship between changeable working condition parameters and operating parameters is typically not taken into account in a model while studying ORC systems. It is insufficient to analyze the system performance changes solely on changes in the performance parameters of the heat exchangers. Furthermore, a model perspective of the system control solution is absent from the steady-state control of the system when the heat source varies. In this paper, we created a system model for the application scenario of a 100–200 kW ORC system with brazed plate heat exchangers in order to address the aforementioned issues using MATLAB R2016b. Additionally, a sensitivity analysis of the system was conducted based on heat exchangers of performance variations. In addition, a modeling computation and adjustment scheme were put forth to guarantee that the system could continue to produce steady power production even when the temperature of the heat source fluctuated. Preliminary results showed that the system's internal parameters included its evaporation pressure and condensation temperature. An increase in evaporation pressure will reduce the mass flow rate and heat flux of an evaporator, thus reducing the heat transfer coefficient. The two-phase region of the evaporator accounted for the highest proportion, of 70.22%, and continued to increase to 75.83%, followed by the supercooling region, and gradually decreasing. The utilization rate of the evaporator decreased from 74.85% to 38.32%. The system output power increased first and then decreased, with a maximum value of 153.11 kW. The system efficiency increased from 5.74% to 11.04%. The increase in condensation temperature increased the proportion of the two-phase region and the superheating region, and the mass flow rate did not change much. The increase in heat flux increased the heat transfer coefficient from 1721.31 W/(m2·K) to 2374.77 W/(m2·K), and the utilization rate of the evaporator decreased from 70.56% to 51.91%. The aforementioned change rules were used in the building of the steady-state regulation model to balance out the changes in the generating power as the heat source temperature increased. The model output was cross-checked and validated against pertinent experimental test literature data. The results of this research can serve as a valid and useful guide for ORC system design and practical applications. [ABSTRACT FROM AUTHOR]

Copyright of Duzce University Journal of Science & Technology is the property of Duzce University Journal of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Duzce University Journal of Science & Technology is the property of Duzce University Journal of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Low-Carbon Chemistry & Chemical Engineering is the property of Low-Carbon Chemistry & Chemical Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work demonstrates the potential of CO2 + SiCl4 binary mixture as a working fluid for power generation cycle. Recompression Brayton cycle configuration is considered due to its proven record of high performance for medium- to high-temperature sources. The objective of this study is to assess the thermodynamic performance of a recompression Brayton cycle using a CO2 + SiCl4 binary mixture as a working fluid, particularly under warm climate conditions. The cycle is simulated using the Peng–Robinson equation of state in Aspen Hysys (v11) software, and the model is validated by comparing VLE data against experimental data from the literature. The analysis involves the assessment of cycle's thermal efficiency and exergy efficiency under warm climatic conditions, with a minimum cycle temperature of 40 °C. The results demonstrate a notable improvement in the cycle's thermodynamic performance with CO2 + SiCl4 binary mixture compared to pure CO2. A small concentration (5%) of SiCl4 in CO2 increases the thermal efficiency of the cycle from 41.7% to 43.4%. Moreover, irreversibility losses in the cooler and the heat recovery unit are significantly lower with the CO2 + SiCl4 binary mixture than with pure CO2. This improvement enhances the overall exergy efficiency of the cycle, increasing it from 62.1% to 70.2%. The primary reason for this enhancement is the substantial reduction in irreversibility losses in both the cooler and the HTR. This study reveals that when using a CO2 + SiCl4 mixture, the concentration must be optimized to avoid condensation in the compressor, which can cause physical damage to the compressor blades and other components, as well as increase power input. This issue arises from the higher glide temperature of the mixture at increased SiCl4 concentrations and the limited heat recovery from the cycle. [ABSTRACT FROM AUTHOR]

Renewable energy is one of environmentally friendly strategies to reduce the environmental pollution caused by energy generation from fossil fuels and reach sustainable development. In this current study, a geothermal driven multi-generation system to provide power, heating, freshwater, hydrogen and oxygen demands is investigated. The main components are encompassed single-pressure organic Rankine cycle, reverse osmosis desalination unit, domestic water heater and proton exchange membrane electrolyzer. For this purpose, energy, exergy, economic and exergoenvironmental (4E) evaluations are accomplished upon proposed system. Non-dominant sorting genetic algorithm has been considered as optimization method that leads to reveal the maximum and minimum of exergy efficiency and total annual cost (TAC) rate as two objective functions. In addition, sensitivity analysis is performed to reveal the roles of design parameters on the system performance and productivity from different standpoints. The optimal results showed that exergy efficiency and TAC increased, as operating temperature of PEM electrolyzer enhances. In terms of economic analysis, the most percentage of total investment cost is pertained to RO unit which was 58.05%. In addition, exergy efficiency and TAC of the proposed system were 30.42% and 255.96 $/h, respectively. As well, the mass flow rate of freshwater, hydrogen, oxygen, net power output and heating production were obtained 3146.7 m3/day, 0.42 m3/day, 3.35 m3/day, 1556.2 kW and 18,586 kW, respectively. Furthermore, by taking into account exergoenvironmental analysis, the environmental impact rate of power, heating, freshwater and hydrogen–oxygen production 2.331 × 10−5 pts/kJh, 3.668 × 10−3 pts/kJh, 1.45 pts/m3h and 11.42 pts/kgh, respectively. Eventually, the optimal outcomes from various perspectives were compared and argued. [ABSTRACT FROM AUTHOR]

Geothermal energy is utilized due to its sustainability and ability to provide a continuous low-emission source of heat, making it an ideal complement to the high-efficiency requirements of modern power plants. This study investigates a novel configuration coupling a solid oxide fuel cell-gas turbine unit with a dual-flash binary geothermal structure, enhanced by low-temperature electricity generation and hydrogen production subsystems. This configuration incorporates a regenerative steam Rankine cycle and a proton exchange membrane electrolyzer to achieve an efficient overall design. The setup is evaluated from thermodynamic and economic perspectives using a non-dominated sorting genetic algorithm-II for optimization. A complete parametric study assesses the sensitivity of critical variables. Multi-objective optimization is conducted across three scenarios considering exergy efficiency, hydrogen production rate, sum unit cost of products, and the payback period as objective functions. Results indicate an optimal exergy efficiency of 56.95% and a hydrogen production rate of 0.22 kg/h, with a product unit cost of $7.06/GJ and a payback period of 1.12 years. The parametric study underscores the significant impact of the number of solid oxide fuel cells and their existing density on key variables of the presented configuration. This study highlights the system's potential for efficient and economically feasible power and hydrogen production. • Investigating a novel geothermal-solid oxide fuel cell-gas turbine configuration. • Combining Rankine cycle and proton exchange membrane electrolyzer for higher efficiency. • Enhancing the thermodynamic and economic performances through multi heat recovery. • Achieving 56.95% exergy efficiency and 0.22 kg/h hydrogen production rate. • Achieving unit cost of $7.06/GJ and payback period of 1.12 years. [ABSTRACT FROM AUTHOR]

To comply with the trend of emission reduction and energy-saving in the industrial sector, a novel integration of the hydrogen liquefaction process based on reversed Brayton cycle (RBC) with the organic Rankine cycle (ORC), for waste heat recovery is proposed. The high temperature gas in the compressor outlet of RBC, which is typically wasted in air-coolers, is recovered in ORC and used as the heat source for power generation for the hydrogen liquefaction process. Thermodynamic analysis showed that compared to the conventional system COP increased by 17.95% from 0.11 to 0.14 and specific energy consumption (SEC) decreased by 16.33% from 10.84 to 9.07 kWh/kg LH2. Parametric analysis was conducted to evaluate the impact of pressure ratio, evaporator temperature and minimum temperature difference (M Δ T) in heat exchangers, on system performance. Changes in these variables affect the system performance and heat transfer area in opposite directions, thus multi-objective optimization by the genetic algorithm was performed to determine the optimum operating conditions. The SEC and the net present value (NPV) were selected as objective functions and were optimized simultaneously. Results from the optimization process indicate that the SEC and NPV were found to be 9.165 kWh/kgH 2 and 1.55 million dollars with the optimal evaporator temperature of 365 K, pressure ratio of 2.85, and the M Δ T of 7.79. • A novel design of hydrogen liquefaction process with heat recovery is examined. • Reversed Brayton cycle is integrated with organic Rankine cycle for the process. • The specific energy consumption is decreased by 16.33% than the conventional one. • Multi-objective genetic algorithm is used to evaluate techo-economic viability. [ABSTRACT FROM AUTHOR]