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Hybrid solar–biomass organic Rankine cycle (ORC) systems represent a promising avenue for sustainable energy production by combining abundant but intermittent solar energy with the reliable biomass energy. This study conducts a detailed thermodynamic and economic assessment of these hybrid systems, focusing on their potential to enhance energy efficiency and reduce greenhouse gas emissions. The study also evaluates the performance of various working fluids, identifying optimal configurations for different operating conditions. A key finding is that the hybrid system, with an optimized solar–biomass ratio, achieves up to a 21 to 31% improvement in efficiency and a 33% reduction in levelized cost of electricity (LCOE) compared to solar-only systems. Additionally, the study examines case studies of real-world applications, offering insights into the scalability and cost-effectiveness of these systems in regions with high solar irradiation and biomass availability. These results underline the need for continued technological innovation and policy support to promote widespread adoption of hybrid ORC systems, particularly in the context of global decarbonization efforts. [ABSTRACT FROM AUTHOR]

Hybrid solar–biomass organic Rankine cycle (ORC) systems represent a promising avenue for sustainable energy production by combining abundant but intermittent solar energy with the reliable biomass energy. This study conducts a detailed thermodynamic and economic assessment of these hybrid systems, focusing on their potential to enhance energy efficiency and reduce greenhouse gas emissions. The study also evaluates the performance of various working fluids, identifying optimal configurations for different operating conditions. A key finding is that the hybrid system, with an optimized solar–biomass ratio, achieves up to a 21 to 31% improvement in efficiency and a 33% reduction in levelized cost of electricity (LCOE) compared to solar-only systems. Additionally, the study examines case studies of real-world applications, offering insights into the scalability and cost-effectiveness of these systems in regions with high solar irradiation and biomass availability. These results underline the need for continued technological innovation and policy support to promote widespread adoption of hybrid ORC systems, particularly in the context of global decarbonization efforts.

Natural gas stations require a preheating stage to prevent the formation of hydrates inside of them provoked by a sudden decompression process of the natural gas. The preheating process has been investigated to improve efficiency and to reduce costs as well. This work studies the behavior of a natural gas decompression station with a first-stage preheating process using a vortex tube and a geothermal heat exchanger, followed by a second stage involving a water bath heater (heating vat). An energetic, exergetic, and exergoeconomic study has been carried out based on a mathematical model and the theory of exergetic cost, obtaining key thermodynamic and thermoeconomic variables, including exergy flows and equipment costs. A heat flow of 26.41 kW was obtained in the geothermal preheating stage; meanwhile, a 60.43 kW heat flow was obtained in the heating vat. The results showed a saving in station fuel using only 2.046% of the natural gas in the system at the second preheating stage. Also, the system was optimized, obtaining a 15.73% reduction in the decompressed natural gas cost. These findings show the possibility of implementing these systems in zones with many geothermal resources to reach a constant, profitable natural gas supply in areas where a pipeline network does not exist. [ABSTRACT FROM AUTHOR]

Liquefaction of natural gas (LNG) is an energy-intensive process with large CO2 emissions. This study addresses these problems by introducing a novel hybrid integration between the propane pre-cooled mixed-refrigerant (C3MR) liquefaction process and concentrated solar power (CSP), utilizing an intercooled supercritical CO2 power block. The proposed system is designed to minimize or eliminate the need for thermal energy storage (TES) and reduce CO2 emissions while providing economic benefits. These benefits are obtained mainly by recovering the cold energy of the flash-gas of the C3MR process through the precooling process of the sCO2 cycle. Then, the flash-gas is stored and combusted (using an auxiliary heater (AH)) at nighttime or when CSP is insufficient to meet the power demand. Five integration cases are evaluated from energetic, exergetic, economic, and environmental points of view: the sCO2 cycle is driven by CSP and its thermal energy storage (TES) without AH in Case-1, by CSP+TES+AH in Case-2 to Case-4 with different contribution from TES and AH, and by CSP+AH without TES in Case-5. In addition, this study optimizes the operating parameters of the hybrid system to further enhance its economic and environmental benefits. The proposed system reduces the CSP field size, minimizes or eliminates the need for TES, and reduces or eliminates CO2 emissions. The optimized results show that Case-2 and Case-5 reduced the levelized cost of electricity from 14.16¢/kWh to 10.35¢/kWh and 8.19¢/kWh, respectively, and reduced the CO2 emissions by 86% and 36%. This study contributes to the field by introducing a novel hybrid integration between the C3MR process and CSP system, providing thorough evaluations of its performance and benefits, and providing significant benefits to the decarbonization strategies of LNG and other industrial processes.

In this study, a thermodynamic model was designed with the Aspen Plus program and optimized multidimensionally of the Afyon biogas power plant to reduce the unit electricity cost and produce green hydrogen. The model also includes ORC integration to use the exhaust gas energy of the existing power plant. In the model, which includes the whole process from biomass receiving to final electricity production, the plant produces 4000 kW of net electrical power. As a result of ORC integration and optimization, the net electricity production of the plant and ORC were determined as 4625.42 kW and 1215.31 kW, respectively. These values correspond to 0.039 $/kWh unit electricity cost. The power obtained in ORC is stored by producing hydrogen during periods of low electricity demand. For this purpose, ORC power is primarily used to electrolyze H2S (green hydrogen) released in biogas production. The rest of the power is used in the electrolysis of water. Hydrogen, released in biogas production, is added to the storage process. As a result, approximately 7.447 kg/min of hydrogen is produced at the power plant, costing 0.18 $/kg. [ABSTRACT FROM AUTHOR]

The advanced exergy and exergoeconomic analysis methodologies excel over their conventional counterparts by quantifying endogenous/exogenous exergy destruction rates and related costs that reveal the interactions among system components. By quantifying avoidable/unavoidable losses, they also reveal the potentials for component improvements that are practically achievable. These data are imperative for improving the cost-effectiveness of thermal systems. This paper presents the performances of a complex gas-fired power plant obtained via an advanced exergoeconomic analysis. The study advances existing studies by undertaking second-tier splitting of exergy destruction cost rates and associated investment cost rates to determine avoidable endogenous, unavoidable endogenous, avoidable exogenous, and unavoidable exogenous cost rates of the plant's components. Component exergy destruction cost rates were found to be predominantly unavoidable, while most of the component investment cost rates were avoidable. Except for the low pressure heater 3, exergy destruction cost rates are endogenous in all the plant components, contributing 84% of overall cost rates. The proportions of exergy destruction cost rates and investment cost rates of the plant that are avoidable endogenous were 21% and 28% respectively, while the respective portions that are avoidable exogenous were 4% and 27%. Furthermore, it was shown that as much as 96.3% improvements in overall plant cost-effectiveness were achievable by eliminating avoidable endogenous exergy destruction cost rates and investment cost rates for major components of the plant. [ABSTRACT FROM AUTHOR]

The choice of refrigerant and expander is always one of the main concerns of researchers using organic Rankine cycles. The problem of using the organic Rankine cycle becomes more complicated when there are two waste heat sources with different temperatures in a system, such as exhaust gas and jacket water heat sources in an internal combustion engine. Hence, in this paper, a thermoeconomic program is developed using four types of volumetric expanders, including piston, screw, scroll and root, and eight different organic fluids in the series double cascade-evaporator organic Rankine cycle. The studied organic fluids were selected to cover a wide range of pressure levels in the series double cascade-evaporator organic Rankine cycle, including R245 FA, R123, n-pentane, acetone, n-heptane, benzene, n-octane and toluene. In the present study, 16 different pairs of expanders were examined for a cohort of 8 dissimilar fluids, resulting in an aggregate of 128 distinctive cases. In each of the 128 different cases, the important parameters, including power production, exergetic efficiency, total investment cost, net present value and levelized cost of electricity generation, are calculated. Also, the Pareto method is used to select the best organic fluid and expander pair. The results show the fluids with lower critical temperatures performed better due to the pressure ratio limit. The lowest cost of the expander compared to the total cost was 4.98%, related to the pair of root–scroll expanders, and the highest cost of 48.21% was related to the piston–screw expander pair. The lowest total investment cost was 377,478$ for the n-pentane and the piston–scroll expander pair. The screw expander costs more than other expanders, especially when in the low-pressure cycle. According to the optimization results, the optimal pair of expanders for the series double cascade-evaporator organic Rankine cycle system is scroll–scroll with n-pentane as the working fluid. Additionally, the exergetic efficiency, payback period and total investment cost values in this case are 0.3945, 4.089 years and 385,786$, respectively. [ABSTRACT FROM AUTHOR]

This research presents the proposal of a double ejector-two flash tank absorption refrigeration cycle, in which vapor and liquid ejectors are implemented simultaneously before the condensers and absorbers components. For the vapor ejector simulation, the shock circle approach is used. The internal environment of the vapor ejector, including the chocking phenomenon and the irreversible shock process, is also thoroughly examined. It is proposed that ejectors and flash tanks can improve the system performance. It is possible to improve the ejector entrainment ratio by incorporating a flash tank between the evaporator and condenser, which would also increase the evaporator cooling effect. Moreover, a second flash tank is installed between the generator and the absorber, which allows the generator to operate at a lower temperature and thus reduces the generator heat load. Consequently, the system's COP (coefficient of performance) increases. Furthermore, the unit cost of the final product in a wide range of operational conditions is calculated. The findings revealed up to 56.8% increase in the COP. The improvement of the maximum exergetic efficiency in the new cycle compared to the basic cycle also reaches 22.5%. Moreover, the thermoeconomic investigation show up to 34.6%. reduction in product cost.

Türkiye is the largest cement producer of Europe and the second biggest cement exporter in the world. The industry is responsible for more than 8% of global carbon dioxide (CO2) emissions and around 15% of the primary energy consumed worldwide. In this paper, the specific energy consumption (SEC) and related emissions of a real scale cement factory currently running in Türkiye have been decreased by investigating the effects of moisture rate of the raw materials and the hot gas transfer to the grinding unit. The data has been collected in the factory site by using the monitoring equipment and real time detection over a 24-month period. Energy and exergy destructions and exergetic cost distributions are determined by using specific exergy costing method (SPECO) for all units of the factory. The specific exergetic consumption (SExC) and production (MC) costs of raw meal are calculated to be 5.05 $/GJ and 4.13 $/ton, respectively. It is investigated that the hot gas supply to the grinding unit and decreasing the moisture rate of feeding materials decreased the SPECO of raw meal, clinker and cement by 8.25%, 5.49% and 4.89% respectively. The applications provide 184.69 MJ reduction in specific energy consumption (SEC) per ton of cement produced and blocked 75,343.37 tons of CO2 emissions per year and reduced the cement production cost to 40.47 $/ton corresponding to a saving of $2.06 M per year. It has been demonstrated that it is very important to keep the moisture content of raw materials used in the cement industry as low as possible in terms of reducing energy consumption and manufacturing costs for sustainable production. [ABSTRACT FROM AUTHOR]

This article presents a novel and comprehensive approach for the thermoeconomic evaluation of subcritical and supercritical isobutane cycles for geothermal temperatures of Tgeo = 100–200 °C. The isobutane cycles are optimized with respect to the maximum net power or minimum levelized cost of electricity (LCOE). Cycle optimization is also included, using a minimum superheat temperature to avoid turbine erosion, which is usually neglected in the literature. The results show that economic optimums are found in the far superheated region, while thermal optimums are obtained with dry saturated or with slightly superheated vapor at the turbine inlet (ΔTsup < 5 °C). Supercritical cycles achieve better thermal performance than subcritical cycles for Tgeo = 179–200 °C. Internal heat recuperation improves the cycle performance: the net power output increases and the LCOE decreases, but specific installation costs (SICs) increase due to the additional heat exchanger. For geothermal temperatures of Tgeo = 120 → 150 °C, the costs are LCOE = 100 → 80 USD2022/MWh and SIC = 7000 → 5250 USD2022/kW, while for geothermal temperatures of Tgeo = 150 → 200 °C, the estimated costs are LCOE = 80 → 70 USD2022/MWh and SIC = 5250 → 4600 USD2022/kW. [ABSTRACT FROM AUTHOR]

A state-of-art multi-generation plant integrated with a scramjet multi-cooling cycle for power, hydrogen, ammonia, and freshwater generation was analyzed from an energy, exergy, exergoeconomic as well as environmental (4E) standpoint. The coolant of the cooling cycle was the fuel of the scramjet cycle and in terms of optimizing consumed power, this cycle is benefiting from four-stage compressors. To improve the rate of hydrogen production, a methanol steam reforming procedure was employed. To provide fresh water, a reverse osmosis membrane was employed and integrated into the plant. To consider the powers of input design variables on the implementation criteria of the plant and reduce CO and CO 2 emission, an exhaustive parametric investigation was performed. The thermodynamic efficiencies, the sum unit cost of the products, the system emission rate, and the environment penalty cost rate as well as values of the products as the multi-generation plant's performance criteria were computed. Raising the hydrogen mole fraction caused an increase in the emission rate. [ABSTRACT FROM AUTHOR]

Enhancing the sustainability and diversification of Iraq's electricity system is a strategic objective. Achieving this goal depends critically on increasing the use of renewable energy sources (RESs). The significance of developing solar-powered technologies becomes essential at this point. Iraq, similar to other places with high average direct normal irradiation, is a good location for concentrated solar thermal power (CSP) technology. This study aims to recover the waste heat from the gas turbine cycle (GTC) in the Al-Qayara power plant in Iraq and integrate it with a solar power tower. A thermoeconomic analysis has been done to support the installation of an integrated solar combined cycle (ISCC), which uses concentrated solar tower technology. The results indicate that the examined power plant has a total capacity of 561.5 MW, of which 130.4 MW is due to the waste heat recovery of G.T.s, and 68 MW. is from CSP. Due to the waste heat recovery of GTC, the thermal and exergy efficiencies increase by 10.99 and 10.61%, respectively, and the overall unit cost of production is 11.43 USD/MWh. For ISCC, the thermal and exergy efficiencies increase by 17.96 and 17.34%, respectively, and the overall unit cost of production is 12.39 USD/MWh. The integrated solar combined cycle's lowest monthly capacity was about 539 MW in September, while its highest monthly capacity was approximately 574.6 MW in April. [ABSTRACT FROM AUTHOR]

The main purpose of this study is to evaluate the thermodynamic and economic performance of using a solar chimney and wind turbine to help generate electricity in a multigeneration system. The proposed system is designed to generate power, heating, cooling, hot water, and steam. Parametric studies were conducted to evaluate the effects of various parameters such as Brayton cycle turbine inlet pressure, organic Rankine cycle turbine inlet temperature, solar radiation, wind speed, and absorption refrigeration cycle evaporator temperature on the system efficiency. The effects of these parameters on the energy, exergy, and economic efficiencies of the whole system were investigated. The results showed that the highest energy efficiency and total exergy of the multigeneration system were 22.12% and 11.4%, respectively. Also, the total power generation capacity of the studied system was calculated to be 2103 kW. The results also depicted that the highest rate of exergy destruction for the main components of the system is found in the parabolic dish solar collector. Increasing the turbine inlet pressure, the average wind velocity of the wind turbine and, evaporator temperature increasing of absorption refrigeration cycle has a positive effect on the efficiency of the proposed system.

In the current energy and environmental framework, the environmental impact of the road transport sector and the urban waste management and disposal are extremely important for highly crowded cities. This work assesses the energy, economic and environmental performance of an innovative paradigm for the full decarbonisation of the road transport sector. This problem is integrated with the management of the organic fraction of municipal solid waste. In particular, the proposed technology is based on an anaerobic digestion plant coupled with a biogas upgrading unit, for the production of biomethane. In addition, photovoltaic panels and solar thermal collectors are also considered for matching electrical and thermal demands, in order to achieve a fully-renewable system. To this scope, the system also includes suitable thermal and electric storages. The economic analysis also considers specific public funding policies, currently available for this technology. This system aims to be a novel paradigm in the energy scenario of waste disposal and road transport sector refurbishment. TRNSYS software was adopted to perform an accurate dynamic simulation for a one-year operation of the system. The anaerobic digestion model is developed by the authors in MatLab and integrated in TRNSYS, for dynamic simulation purpose. Results show that the plant is almost self-sufficient due to the integration of storage systems for both the thermal and electric energy. The photovoltaic system is able to reduce by 45% the energy dependence from the grid. Energy and environmental analyses show a Primary Energy Saving of 126% and a reduction of CO2 equivalent emissions by 112%. The economic feasibility analysis shows a promising Simple Payback period of 6 years.

The improvement of the overall utilization rate of compressed natural gas (CNG) engine fuel is the basis of efficient energy utilization. On the foundation of heat balance theory of internal combustion engines, this study fully considers the operation characteristics of CNG engines and systematically analyzes the distribution characteristics of different waste heat under variable working conditions. The nonlinear relationship between speed and intercooler heat source becomes evident with the increasing of intake mass flow rate. In accordance with the structural characteristics, the thermodynamic model, heat transfer model and environmental model of dual-loop organic Rankine cycle (DORC) are constructed. The system potential in full working environments is systematically evaluated. Compared with the speed, airmass flow has a significant effect on comprehensive performance of loop. The maximum power, heat transfer area and power output of per unit heat transfer area (POPA) of DORC are 36.42 kW, 23.34 m2, and 1.75 kW/m2, respectively. According to the operating characteristics of different loops, the variation laws of loop performance under the influence of multiple parameters are analyzed. The synergistic influence laws of multiple variables on system performance are also analyzed. [ABSTRACT FROM AUTHOR]

In this work, a natural gas assisted geothermal central heating system in northwestern Turkey utilising low enthalpy geothermal fluid and natural gas as the sources for space heating was analyzed.The study comprised energy, exergy and thermoeconomic analyses of the system under hybrid operating conditions (i.e., from 1 January 2020 to 31 March 2020). The data were collected from a basis of the facility which operates the system. The values about the heat pumps were obtained from the department of the sales company in Istanbul, Turkey and the ‘Average Values for Hybrid Case’ were determined. This work covers energetically, exergetically and thermoeconomically assessment of the system in question through its all stages. The results were found with regard to the system performance investigation. The whole system efficiencies of energy and exergy were found as 56.77% and 49.93% respectively. The exergy cost value per hour and the thermoeconomic factor were calculated as 411.242 €/h and 9.8% respectively.

This paper considers the possibility of using liquid-vapor ejectors in condensing units of steam turbines. This unit is designed for pumping out a steam-air mixture from a steam turbine condenser, in which the process occurs at a pressure lower than atmospheric. In the traditional scheme, this is provided by a two-stage steam-jet ejector unit. The proposed scheme involves the use of a single-stage liquid-vapor ejector and its possible pre-vacuum mode of operation in conjunction with a liquid- ring vacuum pump. A working process of the liquid-vapor ejector does not require the supply of working steam from the outside since its generation occurs in the active nozzle of the liquid-vapor ejector. A description of the traditional scheme and the proposed options is given, which are different both in the scheme solution and in the ope rating parameters. The object of this study is a liquid-vapor ejector, which is used in the condensing system of a steam turbine. Thermodynamic calculation of the proposed circuit solutions was carried out. As a result, the necessary mode parameters of the schemes were determined. To assess the feasibility of using a liquid-vapor ejector in the condensation systems of steam turbines, an exergy analysis was performed. The proposed scheme makes it possible to increase efficiency by 2.3 times, and when used with a liquid-ring vacuum pump – by 2.44 times. To assess the economic efficiency of the modernization of the condensing system, thermoeconomic analysis was performed. The use of the proposed scheme makes it possible to reduce the cost of generating boiler steam and reduce the cost of the resulting product of the steam turbine unit by about 51 %. The estimated cost of a unit of the amount of boiler steam consumed per ton of product and the unit cost of steam were established [ABSTRACT FROM AUTHOR]

Compressed-air energy storage has been considered as a promising technology to smooth the fluctuations of renewable energy sources and improve the peak-shaving flexibility capacity of power systems. In order to improve the energy degree of compression heat and enhance the system performance, the current paper described a novel combined heating and power system that integrates compressed-air energy storage with thermochemical technology. In the proposed system, the compression heat is coupled with methanol decomposition reaction to convert the thermal energy to chemical energy (H2 and CO). A sensitivity analysis was carried out to investigate the effects of five key parameters on the system performance. The results indicated that higher values of air-to-methanol ratio, pressure ratio, and isentropic efficiency of gas turbine have positive influences on the thermodynamic performance of the proposed system. In addition, the multiobjective optimization was implemented to ascertain the optimum performance from the aspect of thermodynamics and economics. The optimal condition selected using the technique for order preference by similarity to an ideal solution (TOPSIS) method demonstrated that the exergy efficiency and levelized cost of energy of the proposed system are 39.42% and $96.58/MWh , respectively. [ABSTRACT FROM AUTHOR]

The maritime industry will continue to see increasing regulatory requirements to reduce carbon emissions from ships' operations. Improving the energy efficiency of ships with waste heat recovery systems based on the organic Rankine cycle (ORC) is an attractive way to meet these tightening requirements. The operational profile of a ship has a huge influence on the feasibility of installing ORC onboard as it affects the waste heat source profile from the diesel engines. However, to date, scant attention has been paid to examining the effects that the operational profile has on the marine application of ORC as it is both difficult and expensive to obtain. The present paper aims to describe a methodology that can overcome this problem by developing a generic ship speed profile that defines the ship's operational profile. This speed profile works together with a fit-for-purpose diesel engine waste heat model to derive a waste heat source profile that is used as the input to a thermoeconomic analysis that can justify the installation of ORC. The proposed methodology allows for an objective comparison of the feasibility of ORC subjected to variations in the operational profile. Furthermore, the optimum ORC design can be identified to meet payback time expectations of different shipowners. [ABSTRACT FROM AUTHOR]

Summary: For the global future energy systems, concentrated solar power (CSP) and direct CO2 capture systems are of the most important key technologies, however, each of these systems has shortcomings. This study addresses the solar intermittency and power control complexity of the CSP systems and the substantial energy penalty of the direct oxy‐combustion (DOC) supercritical carbon dioxide (sCO2) power systems by integrating both systems. Herein, innovative power cycle configurations that integrate the CSP tower system with DOC sCO2 power cycle are introduced. The configurations include two basic cycles for comparison and validation purposes and three integrated cycles. The basic configurations are: an intercooled sCO2 power cycle driven by DOC system (S1), and a stand‐alone basic CSP tower system (S2). The integrated configurations are: CSP/DOC system where the CSP works as a preheater (S3); CSP/DOC system where the CSP works as a reheater (S4); and CSP/DOC system where each system heats part of the working fluid to drive its high‐pressure turbine (S5). The hybrid configurations reduce the fuel and the parasitic power consumptions of the basic DOC systems (S1) and reduce the capital cost associated with the conventional CSP systems (S2) by eliminating the need for thermal storage. Over practical ranges of operational parameters, comprehensive thermoeconomic, exergoeconomic, and optimization analyses for the proposed configurations are performed. Compared to the conventional CSP system, the LCOE of the hybrid system is lower by 50%. Among the hybrid configurations, the energetic and exergetic performances of S4 are the best with the lowest LCOE. According to the optimization analysis, S4 has a thermal efficiency of 55.29% at LCOEs of 7.705¢/kWh. S3, S5, S2, and S1 have thermal efficiencies of 52.90%, 48.72%, 45.56%, and 40.54% at LCOE of 7.970, 8.138, 7.864, and 6.351¢/kWh, respectively. [ABSTRACT FROM AUTHOR]

The heat pumps are frequently used in domestic and industrial applications for hot water supply. The present paper aims to thermodynamically investigate the impacts of the nanoparticle-addition into the lubricants on the energetic, exergetic, and thermoeconomic aspects of a heat pump. In the experiments, air to the water heat pump is separately charged with various metal oxide-based nanoparticles (Al2O3, CuO, and TiO2)-added oils at a constant mass fraction of 0.5%. Polyolester (POE) and 134a are used as a lubricant, and refrigerant, respectively. The mass flow rates of the water passed through the condenser are varied from 10 to 25 g/s with an interval of 5 g/s. In the results, it is observed that the thermal conductivity value noteworthy increases with the presence of nanoparticles in POE. The highest increment in thermal conductivity is found to be 39% for POE + CuO in comparison with that of pure POE. Furthermore, with nanoparticles addition, it is noticed that the COP value generally improves, and the highest improvement for COP value is noticed to be 8% for POE + TiO2 nanolubricant at the mass flow of 25 g/s. Furthermore, exergy efficiency enhances by 3.6%, 1.8%, and 4.5% for POE + Al2O3, POE + CuO, and POE + TiO2, respectively. The lowest heating cost is calculated to be 3.465 ¢/kWh at 20 g/s flow rate for POE + Al2O3. In conclusion, this paper clearly reports that usage of nanoparticles along with lubricants is presenting better energetic, exergetic, and thermoeconomic results rather than the usage of lubricant alone in the heat pumps.

Evaluating Coal-Fired Power Plant (CFPP) performance is a complex process involving the determination of the turbine cycle Heat Rate (TCHR). This study focuses on determining the TCHR by developing a mathematical model. The model, which incorporates economic analysis of the plant, is developed using energy and mass balance relationships of the turbine cycle, validated using plant commissioning data from a 700MWn CFPP located in Perak, Malaysia. Actual plant data from a 700MWn CFPP is utilized to improve the accuracy and increase the confidence of the results of this study. It was found that at the nominal operating load of 729MWg, there is a Heat Rate (HR) deviation of -1,135 kJ/kWh, leading to daily losses of RM240,447 or USD 60,112. Furthermore, it is possible to utilize the developed model at lower loads as the plant is now being used to operate on "cyclic" loads. The daily losses at a lower load of 431MWg are RM125,767 or USD31,442. Thus, the model is able to compare the plant HR at various loads against commissioning data, and economic analysis is able to be carried out effectively. Valuable information for plant operations and performance engineers could be obtained using this model to determine plant HR. [ABSTRACT FROM AUTHOR]

Because of the fossil fuels crisis in recent years, increasing fossil fuel consumption and the oil crisis, energy efficiency is becoming a major concern of the twenty-first century. In this research, the combined cycle of steam Rankine and organic Rankine with the primary mover of the Allam generation cycle has been simulated. The hybrid cycle is configured in such a way that the high temperature waste heat first acts as the steam cycle evaporator and the waste heat output from the steam cycle evaporator is used as the low temperature evaporator of the organic cycle. Then, the effect of changing various parameters such as evaporator temperature and steam cycle condenser pressure on output work values, total irreversibility, energy efficiency, exergy efficiency and exergy-economic variables is investigated. The results show that the energy efficiency and exergy efficiency of the combined cycle are 0.57 and 0.66, respectively, and the amount of output work and total irreversibility are 150,125 kW and 91,237 kW, respectively. Also, according to the study results, a lot of exergy destruction takes place in the system, thus it is recommended to increase the initial price in different components in order to improve the performance of the system. Evaporators and steam cycle condensers are components that should be considered from an exergy-economic perspective, as they have the highest rate for the sum of the initial cost rate and the cost of exergy destruction. [ABSTRACT FROM AUTHOR]

In this paper, a salinity gradient solar pond (SGSP) is used to harness the solar energy for hydrogen production through two cycles. The first cycle includes an absorption power cycle (APC), a proton exchange membrane (PEM) electrolyzer, and a thermoelectric generator (TEG) unit; in the second one, an organic Rankine cycle (ORC) with the zeotropic mixture is used instead of APC. The cycles are analyzed through the thermoeconomic vantage point to discover the effect of key decision variables on the cycles' performance. Finally, NSGA-II is used to optimize both cycles. The results indicate that employing ORC with zeotropic mixture leads to a better performance in comparison to utilizing APC. For the base mode, unit cost product (UCP), exergy, and energy efficiency when APC is employed are 59.9 $/GJ, 23.73%, and 3.84%, respectively. These amounts are 47.27 $/GJ, 29.48%, and 5.86% if ORC with the zeotropic mixture is utilized. The APC and ORC generators have the highest exergy destruction rate which is equal to 6.18 and 10.91 kW. In both cycles, the highest investment cost is related to the turbine and is 0.8275 $/h and 0.976 $/h for the first and second cycles, respectively. In the optimum state the energy efficiency, exergy efficiency, UCP, and H 2 production rate of the system enhances 42.44%, 27.54%,15.95%, and 38.24% when ORC with the zeotropic mixture is used. The maximum H 2 production is 0.47 kg/h, and is obtained when the mass fraction of R142b, LCZ temperature, pumps pressure ratio, generator bubble point temperature are 0.603, 364.35 K, 2.12, 337.67 K, respectively. • The stored heat of a salinity gradient solar pond is used for H 2 production. • Thermoelectric generators and zeotropic mixture are employed. • NSGA-II is used to find the optimum point of the system. • In optimum state η e n , η e x , UCP, and m ˙ H 2 are 6.31%, 34.63%, 44.7 $/GJ, and 0.47 kg/h. [ABSTRACT FROM AUTHOR]

Solar energy systems are widely utilized to obtain environmentally friendly and sustainable electrical and thermal energy that able to be used in many applications. Temperature-controlled solar air heater (SAH) system with a zigzag finned plate and flat plate was designed, manufactured, and tested experimentally in this study. It was determined that the set temperature was 15% higher than the flat plate SAH outlet temperature. The most important cause for this increase, the air is exposed preheating in the first collector. As the heat transfer surface area raised thanks to the zigzag fins in the second collector, the temperature of the air increases even more. SAH system's energy efficiency was found to be 71.15% on average. SAH system's maximum exergy efficiency was determined as 3.7%. The SAH system's average exergy destruction is calculated to be 651.58 W on average. According to the enviroeconomic analysis of the system, hourly CO2 mitigation was found to be 1.04 kg CO2/h and the environmental cost was 1.508 ¢/h. The energy cost was calculated as 0.0834 $/kWh, while the exergoeconomic parameter was calculated as 0.1931 kWh/$. In addition, the energy payback period was determined as 1.35 years, while the exergy payback period was determined as 45.9 years.

Because of population growth, demands for water and energy for domestic, industrial, and agricultural usages are increasing. Considerable research has been conducted in recent years to evaluate the thermodynamics and optimization of desalination systems. One important concept is the capacity to integrate power generation systems with desalination plants. The purpose of this study is to analyze the exergy and thermoeconomics of the combined desalination system (MED) and Allam power generation system. The key advantage of this proposed system is to use the heat generated in the Allam power generation system to operate the desalination system. Similarly, due to the performance of the Allam generation system, the amount of carbon dioxide produced is virtually zero. By determining the processes and solving the governing equations, the properties of the fluids passing through the combined cycle of Allam and MED are determined and thermodynamic, exergetic and thermoeconomic analysis is performed along with the thermoeconomic optimization of the system. In this research, genetic algorithm has been used for optimization and the result has been described in multi-objective optimization. Subsequently, parametric analysis and the effect of design variables on the system cost function have been accomplished. The results show that in a specific vector of decision variables, the objective functions including, the exergetic efficiency and the cost of the product produced by the system are optimized simultaneously. In conventional desalination plants, a boiler is used to supply the steam entering the desalination system. After conducting the model simulation of the desalination system, the Allam generation system is modeled as well. Thus, by combining these two systems, the heat generated by the Allam generation system can be used to evaporate water in the desalination system. In the ideal case, the price of fresh water of using the steam produced by the boiler is $1.131 per cubic meter, and by means of the steam produced by the power generation system would be $1.087 per cubic meter. Hence, the results indicate that combining the desalination system with the Allam generation system provides a 4% reduction. Reducing carbon dioxide emissions is also a significant benefit of this system. [ABSTRACT FROM AUTHOR]

In this paper, the thermoeconomic cost model of a typical gas turbine combined cycle (GTCC) system is established based on the structure theory of thermoeconomics. Because the operation strategy is the basis of the research on the design/off-design condition of GTCC unit. Therefore, the GTCC thermoeconomic performances with different strategies using the inlet guided valve (IGV) control are compared based on the GTCC cost model to analysis the influence of the main parameters on the unit thermoeconomic cost of each component. The variation rules of the thermoeconomic performances of the GTCC unit under design/off-design operating conditions influenced by the operating strategy and ambient temperature are revealed. The results show that the GTCC with the IGV T3-650-F operation strategy has the lowest thermoeconomic cost. Changing the operation strategy of gas turbine (GT) can reduce the generator (GEN) unit thermoeconomic cost. And higher GT inlet/outlet temperature is helpful to reduce the thermoeconomic cost of combined cycle under off-design conditions. The investment on the steam turbine (ST) and the irreversibility of the combustion chamber (CC) have the important influence on the thermoeconomic cost of GTCC system. Reducing the air compressor (AC) inlet air temperature can reduce the thermoeconomic cost of GTCC system.

This research work presents the assessment of the impact of the solar irradiation, the distance from the coast, and the altitude of the location for a Concentrated Solar Power + Photovoltaic + Multi-Effect Distillation (CSP + PV + MED) plant for simultaneous power generation and seawater desalination. For that, a comparative analysis of the thermoeconomic cost of electricity and water (TCE and TCW) at different locations is carried out to determine the most competitive sites where this kind of cogeneration plant can be deployed. Also, multi-objective optimization is performed to assess the optimum sizing that allows reducing the costs. The study considers four Direct Normal Irradiation (DNI) levels (from 2000 to 3500 kWh/m2-yr), six distances from the sea (from 5 to 100 km), and six altitudes (from 20 to 1000 m.a.s.l.). The results show that solar irradiation has the most significant effect on the TCE and TCW, the distance to the sea affects the TCW considerably, and the altitude has a moderate impact despite its impact is substantially lower than the other two factors. Also, cost maps of the TCE and TCW giving insights about which locations have a higher potential for developing CSP + PV + MED plants are presented. From these maps, it has been found that the potential inland locations to reach TCE and TCW under 100 $/MWh and TCW 2 $/m3 should have high DNI (at least 300 kWh/m2-yr above the coast level), distances from the coast up to 60 km, and altitudes up to 750–1000 m.

n this study, energy, exergy, thermoecological, sustainability, thermoeconomic and exergoeconomic analyzes for piston-prop engines used in helicopters are explained and these analyses are applied on a pistonprop engine with 190 SHP power. Firstly, the piston-prop engine is considered as a thermodynamic system and accordingly the control volume, inlet and outlet flows, balance equations and dead state conditions of the system are determined. According to the findings, the energy efficiency of the system is found as 15.51%, while the exergy efficiency is calculated as 11%. The system’s entropy production, sustainability index, thermoecological performance coefficient, thermoeconomic parameter value, exergoeconomic parameter value due to loss exergy, exergoeconomic parameter value due to destruction exergy and total exergoeconomic parameter value are found as 2,940 W/K, 1.124, 0.161, 2.20 W/TL, 1.29 W/TL, 2.50 W/TL ve 3.79 W/TL, respectively. As a result of the analyses, it is noticed that the energy generated by the fuel entering the system is largely lost and depleted. In view of the obtained results, in addition to increasing the efficiency and performance of the engine, in order to reduce the losses and irreversibility in the system, it can be recommended to improve the cooling technologies of this type of engines [ABSTRACT FROM AUTHOR]

A growing population with depleting water resources has increased the requirement for desalination systems. Large‐scale desalination plants have seen a growth in the recent period; however, the small‐scale (SS) decentralized desalination plants' need has not been realized for the rural population. Low specific heat consumption for multieffect desalination systems makes it suitable for such decentralized operation. The challenge now lies in determining the system capacity and optimal operational range for the SS requirements. In this study, the thermoeconomic model for an SS multieffect desalination system for various configurations is developed. Optimization of the SS plant for the number of effects is performed to determine the optimal operational range of motive steam pressure, motive steam flow rate, and feed water flow rate. Total distillate production and freshwater cost are focused on objectives and constraints imposed over the input parameters with SS production. The results reveal that for a distillate production of 750 L/day, the motive steam flow requirement is estimated to be 25–35 kg/h with a pressure range of 2–5 bar. This study provided an overview for selecting the number of effects based on the commercial aspect of total production requirements. [ABSTRACT FROM AUTHOR]

Despite the availability of new alternative energy sources, growing worldwide energy demand and emissions targets lead power plants to work optimizing performances. In this new scenario in which renewable energies are increasingly taking the field, it is also important to produce energy at a low price. Moreover, the variability of the energy market price complicates the analysis. Comparison between the produced energy cost and the market price is necessary to get a return on investment. In this context, the paper investigates the implications of using a gas turbine in an energy system estimating the plant layout and the number of working hours that guarantees a better profit. The analysis focuses on the study of the start-up and shutdown operation mode to find the optimal solution strategy in the Italian electricity market. [ABSTRACT FROM AUTHOR]

To address environmental pollution effectively, it is crucial to promote the increased utilization of renewable energy sources. Furthermore, an appealing opportunity arises from enhancing the efficiency of renewable-based power plants while diversifying their product output. This study introduces a hybrid system that revolves around renewable resources, with a primary focus on evaluating power generation, hydrogen production, and freshwater extraction. The designed system seamlessly integrates a flash-binary geothermal power plant with a solar system, incorporating cutting-edge phase-change material storage technology. Hydrogen is generated through a combination of steam-methanol reforming and pressure swing adsorption processes. Freshwater is procured utilizing humidification-dehumidification and multi-effect desalination units. In terms of power generation, the system leverages the capabilities of the geothermal power plant alongside a modified Kalina cycle. The performance of this integrated system is rigorously evaluated through a combination of thermodynamic and thermoeconomic approaches. An exergy-economic optimization scenario is employed to determine the most efficient operational mode. The results of this comprehensive analysis reveal that the system can produce 0.0224 kg/s of hydrogen, 8.017 kg/s of freshwater, and generate 215.9 W of net power. Impressively, it achieves an exergy efficiency of 58.3% at a unit cost of $32.23/GJ in the base mode. Furthermore, the optimal operating state boosts efficiency to 60.59%, with a unit cost of $32.22/GJ. Notably, adjustments in the selling price of hydrogen have a significant impact on the system's financial metrics. As the price of hydrogen rises from $5 to $6/kg, the payback period reduces from 4 to 3 years, and the net present value surges from $5.81 million to $10.16 million. • A renewable-based hybrid system is proposed for power, hydrogen, and freshwater production. • Integration of geothermal power plant, solar system, and various desalination units. • Comprehensive thermodynamic and thermoeconomic analysis conducted for system evaluation. • The optimum state achieves 60.59% exergy efficiency and a unit cost of 32.22 $/GJ, with significant financial benefits. [ABSTRACT FROM AUTHOR]

The improvement of the overall utilization rate of compressed natural gas (CNG) engine fuel is the basis of efficient energy utilization. On the foundation of heat balance theory of internal combustion engines, this study fully considers the operation characteristics of CNG engines and systematically analyzes the distribution characteristics of different waste heat under variable working conditions. The nonlinear relationship between speed and intercooler heat source becomes evident with the increasing of intake mass flow rate. In accordance with the structural characteristics, the thermodynamic model, heat transfer model and environmental model of dual-loop organic Rankine cycle (DORC) are constructed. The system potential in full working environments is systematically evaluated. Compared with the speed, airmass flow has a significant effect on comprehensive performance of loop. The maximum power, heat transfer area and power output of per unit heat transfer area (POPA) of DORC are 36.42 kW, 23.34 m2, and 1.75 kW/m2, respectively. According to the operating characteristics of different loops, the variation laws of loop performance under the influence of multiple parameters are analyzed. The synergistic influence laws of multiple variables on system performance are also analyzed.

The maritime industry will continue to see increasing regulatory requirements to reduce carbon emissions from ships’ operations. Improving the energy efficiency of ships with waste heat recovery systems based on the organic Rankine cycle (ORC) is an attractive way to meet these tightening requirements. The operational profile of a ship has a huge influence on the feasibility of installing ORC onboard as it affects the waste heat source profile from the diesel engines. However, to date, scant attention has been paid to examining the effects that the operational profile has on the marine application of ORC as it is both difficult and expensive to obtain. The present paper aims to describe a methodology that can overcome this problem by developing a generic ship speed profile that defines the ship’s operational profile. This speed profile works together with a fit-for-purpose diesel engine waste heat model to derive a waste heat source profile that is used as the input to a thermoeconomic analysis that can justify the installation of ORC. The proposed methodology allows for an objective comparison of the feasibility of ORC subjected to variations in the operational profile. Furthermore, the optimum ORC design can be identified to meet payback time expectations of different shipowners.

This work aims to enhance the energy cost-saving potential of conventional mud-brick by including natural waste materials as insulators. The solid waste materials considered for mud bricks are rice husk, sawdust, coir pith, and fly ash. This work investigates the structural and thermoeconomic performance of four types of insulated mud bricks and three roofs of ferrocement, clay, and ceramic materials. The thermal properties of walls and roofs were measured as per ASTM D 5334 standards. The utilization of solid waste in mud bricks enhanced the structural properties and air-conditioning cost-saving potential of the mud bricks. The results also showed the mitigation of greenhouse gas emissions with the usage of insulated bricks for buildings. The rice husk mud-brick wall showed better results of higher time lag, lower decrement factor, higher air-conditioning cost-savings, acceptable payback periods, and higher annual carbon mitigation values of 11.11 h, 0.24, 1.74 $/m2, 1.17 years, and 33.35 kg/kWh, respectively, among all the studied multilayer walls. Among the roofs, clay tile roof showed a lower decrement factor (0.989), higher time lag (0.73 h), higher air-conditioning cost-savings (2.58 $/m2), lower payback periods (0.61 years), and higher annual carbon mitigation (21.73 kg/kWh). The results are in designing eco-friendly and energy-efficient envelopes for buildings. [ABSTRACT FROM AUTHOR]

Cyclohexane and sec-butyl alcohol are widely used in the pharmaceutical and chemical industries. The separation of cyclohexane/sec-butyl alcohol/water azeotropic mixture is of great significance for mitigating environmental risk, recycling solvents, and maintaining developmental sustainability. Based on the COSMO-SAC model, the infinite dilution activity coefficients of the components were calculated, and the final solvent was further obtained by relative volatility and solvent power screening. Taking the total annual cost as the objective function, the extractive distillation process is optimized based on a sequential iterative optimization algorithm. To further reduce the process energy consumption, several energy-saving processes were explored. Energy-saving processes are compared in terms of total annual cost, CO 2 emissions, and thermodynamic efficiency. It was found that the total annual cost and thermodynamic efficiency of the processes show an increasing trend, while CO 2 emissions show a decreasing trend. The results of stage-exergy indicate that the processes with heat pump are relatively small. The heat pump combined with the thermal coupling extractive distillation process exhibits better thermoeconomic and environmental performance. It provides theoretical guidance for improving the separation and recovery of value organics and energy-saving optimization of processes, which conforms to the theme of sustainable and environmental development. [ABSTRACT FROM AUTHOR]

• Hybrid PTC-TES-biomass ORC-based polygeneration system design for a commercial centre. • The system produces the annual electricity consumed in the commercial centre. • Thermoeconomic analysis provides the cost of the internal flows and final products. • Investment costs reduction leads to system economic feasibility in the medium term. • The system displaces 96.1% of the CO 2 emissions relative to a conventional system. Hybrid renewable polygeneration systems are regarded as key solutions for the sustainable energy supply of buildings. While solar heating and cooling comprises a wide range of technologies, there has been limited research on the combined production of power and cooling only, with little or no heat demand. This study designs and analyzes a hybrid solar–biomass ORC-based polygeneration system from energy, economic, and environmental viewpoints. The polygeneration system is designed to cover the electricity and cooling demands of a commercial center located in Zaragoza, Spain. A parabolic trough collector field coupled with thermal energy storage, and an auxiliary biomass boiler supply heat to an Organic Rankine Cycle (ORC), which generates electricity to cover electrical demands and to produce cooling in mechanical chillers. The biomass boiler supports the solar thermal production to ensure a stable and reliable heat supply to the ORC. The system is connected to the electric grid, so that electricity purchases and sales are possible. The equipment sizing is performed with the goal of achieving a high renewable fraction in the total electricity consumed by the commercial center. The analysis of the proposed plant includes the hourly operation throughout the year, complemented by an economic assessment, considering investment and operation costs, and an estimate of the environmental benefits of the plant. Also, a thermoeconomic analysis is developed to determine the cost formation process of the internal flows and final products of the plant. The unit cost of each flow is broken down into investment and operation cost components. Sensitivity analyses of the investment cost, interest rate, biomass price, and electricity selling price discount are made. The results show that, in economic terms, the system is not presently viable, since the cost of the electricity produced (279.07 €/MWh) is much higher than the electricity purchase price (126.70 €/MWh). In environmental terms, the system is capable of displacing 96.1% of the CO 2 emissions and 85.6% of non-renewable primary energy consumption relative to a conventional system consuming grid electricity only. [ABSTRACT FROM AUTHOR]

A Plant for trigeneration of freshwater, power and cooling has been developed and optimized for higher efficiency and lower plant cost. Parabolic trough collectors with thermal energy storage are considered using thermal oil as the heat transfer fluid. Solar heat is utilized to produce power via a Toluene-based Rankine cycle for power generation and cooling via an Absorption chiller. A part of the generated power is used to run a Reverse Osmosis desalination plant. The solar data is taken from a southern city in Turkey. Exergy efficiency and plant cost rate of the system vary between 9–14% and 287–335 $/h, respectively. A multiobjective optimization study depicts that optimal exergy efficiency of %12.5 is obtainable at a plant cost rate of 328 $/h. Freshwater cost is strongly dependent on the cost of solar electricity and shows a significant fluctuation due to variable solar availability condition. The results of the studied system depict that sustainable and economical plant operation is possible in short/near terms when the investment costs of utilized technologies are competitive with those used in conventional plants.

In this study, the effects of different nanoparticle shapes including blades, cylinders, and bricks on the thermoeconomic optimization of tubular heat exchanger (HE) networks have been studied. Boehmite alumina was used as nanoparticle and water as the base fluid. Optimal results were proposed to improve both thermal effectiveness and total annual cost simultaneously by eight design parameters. In addition, optimization was performed for four nanofluid mass flow rates, 0.5, 1, 1.5, and 2 kg/s. The results show that the application of nanoparticles was accompanied by an improvement in the thermal economic parameters of the HE network, and this improvement rate was noticeable in higher values of effectiveness. However, the results indicate a nanofluid optimal mass flow rate of 1.5 kg/s, whereas there was no significant improvement by increasing mass flow rate to 2 kg/s. The optimum results in this paper showed that the best‐studied nanoparticle shape was blade, followed by brick and cylinder shapes. For example, 9.60%, 10.68%, and 11.20% improvements in the effectiveness were obtained in cylindrical, brick, and blade forms at a fixed cost of 3000 $/year, compared with BF. These improvements are 10.40%, 11.25%, and 11.52%, respectively, for the constant value of total annual cost = 4400 $/year. [ABSTRACT FROM AUTHOR]

The Afyon Geothermal Power Plant is modeled using the Multi-Layer Feed-Forward Artificial Neural Network. The 100 × 8 data set obtained from the real Binary Geothermal Power Plant is divided into two parts: 80 × 8 training data and 20 × 8 test data. Geothermal Power Plant system modeling has been performed numerically on Matlab with three inputs and five outputs. There are ten neurons in the hidden layer in the Artificial Neural Network-based system, and the logarithmic sigmoid transfer function is used as the transfer function in each neuron. The neurons in the output layer have the purelin transfer function. As a result of the training process, the 3.06 × 10E-2 mean square error value was obtained from the ANN-based Binary Geothermal Power Plant system. The main point of the study is the optimization of the binary geothermal power plant. The genetic algorithm method with Artificial Neural Network-based is used for this purpose. The results obtained from the outputs of the Artificial Neural Network-based Binary Geothermal Power Plant system are presented. The plant's geothermal water temperature and mass flow rates are 110 °C and 150 kg/s. Energy and exergy efficiencies of the plant are calculated as 10.4% and 29.7%. The optimized simple payback period and exergy cost of the electricity generated in the plant is calculated as 2.87 years and 0.0176 $/kWh, respectively. Schematic configuration of Afyon Geothermal Power Plant. Image 1 • Modelling of Afyon Geothermal Power Plant is performed numerically based on ANN. • Geothermal temperature and mass flow rate of the plant are 110 °C, and 150 kg/s. • Energy and exergy efficiencies of the plant are calculated as 10.4%, and 29.7%. • The exergetic cost of the electricity from the plant is calculated as 0.0176 $/kWh. [ABSTRACT FROM AUTHOR]

The study explores the possibility of using water (R718) as a refrigerant for a heat pump installation of a heating system. This unit is a vapor compression heat pump with a regenerative heat exchanger in which the vacuum unit based on a liquid-vapor ejector is used instead of a scroll refrigeration compressor. The working process of such an apparatus is based on implementing a fundamentally new cycle that does not require the supply of working steam from the outside. Instead, steam is generated inside the vacuum unit. The article describes the proposed installation and its differences from the traditional one, both in terms of circuit solutions and in terms of the operating cycle. A thermodynamic calculation was performed for the proposed installation with R718 as the working medium and the traditional heat pump systems operating on refrigerants R142b, R254fa, and R410a. As a result of the calculation, the parameters of all the devices included in these schemes were obtained, and the conversion factors of the cycles were determined. To assess the feasibility of using R718 as a working substance and replacing the scroll refrigeration compressor with a liquid-vapor ejector, an exergy analysis was performed. This made it possible to fairly accurately determine the effectiveness of each circuit, since it implemented the possibility of comparing systems using several types of energy (for example, electrical and thermal). As a result, the values of exergetic efficiency of traditional and proposed schemes were obtained. The final stage of the study was the performance of a thermoeconomic analysis. The estimated cost was determined for a unit of heat quantity per ton of the product and per unit of the heated area obtained in a unit with the working substance R718 and traditional installations with the working substances R142b, R254fa, and R410a. [ABSTRACT FROM AUTHOR]

The present paper aims at the optimization and exergy and thermoeconomic analyses of a combined cooling, heat, and power generation system equipped with a thermal energy storage for the use in a residential complex with a gas-fueled internal combustion engine as the prime mover. The system is optimized using the direct search method by minimizing annual cost in two cases of using/not using a thermal energy storage. In case of the use of a thermal energy storage, an engine with a capacity of 2 MW and an operating time of 4000 h are found to be optimal, but when a thermal energy storage is included, an engine with a capacity of 2 MW and an operating time of 5268 hours and a thermal energy storage with a capacity of 18.93 m3 are found to be the optimal options. Both systems are evaluated assuming selling/not selling surplus power to the public power grid. The best case for the performance of the system is to use a thermal energy storage and to sell surplus electricity to the grid. In this case versus the case of excluding the thermal energy storage, primary energy consumption, CO2 emission, operating cost of the system, and power purchase from the public grid are decreased by 20.8, 19.5, 14.3 and 17%, respectively while return on capital is increased by 3.1% resulting in 10.7% higher annual cost of the system. [ABSTRACT FROM AUTHOR]

• System-scale performance assessment is done for a two-phase immersion cooling system. • The best COP and PUE trends are found at the highest server power rate. • Exergy efficiency varies between 8.0 and 18.9% at various operation loads. • Exergy costs are found 3.25 times as higher than the energy costs. The liquid-cooling data center (DC) systems have been becoming important for the rapidly developing high-performance processors since the traditional air-cooled DC systems cannot efficiently manage them due to high heat dissipation rates. Two-phase liquid-immersion cooling is one of the promising direct liquid-cooled DC systems, but its system-scale thermal management performance has not been investigated in detail yet. This study performs the system-scale thermal management of a two-phase liquid-immersion cooling DC system under six different real-time and dynamic operation loads in the range of 3.43-9.17 kW to see the thermodynamic and thermoeconomic performances. The system includes the DC server tank, circulation pump, and dry tower. Results show that the best coefficient of performance (COP) and power usage effectiveness (PUE) values are seen at the highest operation load with 6.67 and 1.15 while the minimum COP and the highest PUE are seen at the lowest operation load with 2.5 and 1.4, respectively. In the component-based assessments, the dry tower is found as the most dominant component according to the exergy destruction ratio analysis, energy costing, and carbon-related costs. The exergy efficiency varies between 8.0% and 18.9% for different operation loads, and the operating temperatures have a crucial impact on the exergetic performances. The thermoeconomic analysis deduces that the levelized product cost is roundly 1.14 S$ · h-1 which means the exergy-related terms (e.g. destruction and loss) increase the costing trends 3.25 times as high compared to the traditional energy-based economic calculations. [ABSTRACT FROM AUTHOR]