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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 work-ing process of such an apparatus is based on implement-ing 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 arti-cle describes the proposed installation and its differ-ences from the traditional one, both in terms of circuit solutions and in terms of the operating cycle. A ther-modynamic calculation was performed for the proposed installation with R718 as the working medium and the traditional heat pump systems operating on refriger-ants R142b, R254fa, and R410a. As a result of the cal-culation, the parameters of all the devices included in these schemes were obtained, and the conversion factors of the cycles were determined. To assess the feasibili-ty 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 effective-ness 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 val-ues of exergetic efficiency of traditional and proposed schemes were obtained. The final stage of the study was the performance of a thermoeconomic analysis. The esti-mated 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.

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.

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

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.

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

In this work, a biomass-fired proton exchange membrane fuel cell integrated with organic Rankine cycle and thermoelectric generator using different gasification agents is proposed for the cogeneration of power and heat as well as hot water production. Both models are comprehensively analyzed and compared from thermodynamic, thermoeconomic, and environmental aspects. A parametric study is performed to evaluate the influence of major decision parameters on the output power, energy and exergy efficiencies, CO2 emission index, and total cost rate of both models. Furthermore, the best model is optimized using genetic algorithm method in MATLAB. The results reveal that using steam as the gasification agent is more suitable in terms of economic and environmental performance indicators. Referring to the exergy and exergoeconomic assessment, in both models, afterburner is one of the significant sources of irreversibility and proton exchange membrane fuel cell has the highest cost of inefficiencies. Results of multi-objective optimization indicate that the output power and total cost rate of the model using steam as the gasification agent are 1.849 kW and 5.094 $/h. Moreover, scatter distribution of the significant variables shows that biomass moisture content and figure of merit are sensitive variables that should be kept at their lowest value.

In this paper, thermodynamic and thermoeconomic analyses, and also optimization of an organic Rankine cycle (ORC) were performed. The system was adapted to an existing solid waste power plant with a 5.66 MW installed power capacity in order to produce additional power from the exhaust gas. The actual operating data of the plant were utilized during all stages of the analyses. The originality of this paper is based on the analysis of the possibility of the energy conversion of an exhaust gas with a temperature of 566 & #x000B0;C into the electricity by utilizing an ORC system in the concept of waste-to-energy. Four different working fluids: toluene, octamethyltrisiloxane (MDM), octamethyl cyclotetrasiloxane (D4) and n-decane were considered and analyzed for the current system. This is also another novelty of this study due to lack of such a study, in the open literature, that deals with an ORC utilized for a typical municipal solid waste power plant. According to the thermoeconomic analyses, toluene was found to be the optimum working fluid with the maximum power output of 584.6 kW and the exergy efficiency of 15.69%. The optimization of the cycle was performed by using the non-dominated sorting genetic algorithm method (NSGA-II) in MATLAB software environment. The optimization results were compared and the deviations of the net power output and the total cost rate were evaluated as & #x2212;5.89%, & #x2212;3.51 & #x00024;/h for toluene; 0.96%, & #x2212;3.60 & #x00024;/h for MDM; 8.45%, & #x2212;2.04 & #x00024;/h for D4 and 2.00%, & #x2212;5.54 & #x00024;/h for n-decane, respectively. © 2018 Elsevier Ltd

Liquefied natural gas (LNG) cold utilized micro cogeneration systems are the feasible and sustainable solutions for the inland regions where the large scale LNG cold utilization or the conventional pipeline systems are not economically applicable. The present study investigates the single and combined systems in three LNG importing countries by using the finite sum modeling which is firstly performed for the LNG cold utilization systems with the sustainability index assessment. To generate electricity, the microturbine is integrated with an LNG vaporizer and an LNG pump in the single system while the combined system includes a Stirling engine and a thermal energy storage tank in addition to the microturbine and LNG cold utilization components. Thermodynamic, environmental, thermoeconomic and sustainable analyses are performed to obtain their yearly performance maps that are extremely difficult to obtain with the conventional dynamic modeling. The yearly performance trends of the net power generation rate, exergetic efficiency, and the levelized product cost are found similar to each other while they have contrary yearly trends with the overall energetic efficiency and the Stirling engine performance parameters. The net generated power rate, the Stirling engine performance parameters, the levelized product cost, the emission rate and the sustainability index have significant changes which must be considered for the real applications while the other factors are able to be neglected during the dynamic analysis since their fluctuations are small. The most convenient time are found at 08:00 am in all the case countries though the corresponding months change for each case country. The combined system is found more feasible than the single system from the thermodynamic, thermoeconomic, environmental and sustainable viewpoints. NRF (Natl Research Foundation, S’pore)

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

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. Agency for Science, Technology and Research (A*STAR) The authors would like to thank the funding supports from the Nanyang Technological University (NTU)-Defense Science and Technology Agency (DSTA) joint project and the Economics Development Board (EDB) Singapore - EcoCampus at NTU project.

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

To contribute to the economic viability of waste heat recovery systems application based on the organic Rankine cycle (ORC) under real operation condition of natural gas engines, this article presents a thermoeconomic optimization results using the particle swarm optimization (PSO) algorithm of a simple ORC (SORC), regenerative ORC (RORC), and double-stage ORC (DORC) integrated to a GE Jenbacher engine type 6, which have not been reported in the literature. Thermoeconomic modeling was proposed for the studied configurations to integrate the exergetic analysis with economic considerations, allowing to reduce the thermoeconomic indicators that most influence the cash flow of the project. The greatest opportunities for improvement were obtained for the DORC, where the results for maximizing net power allowed the maximum value of 99.52 kW, with 85% and 80% efficiencies in the pump and turbine, respectively, while the pinch point temperatures of the evaporator and condenser must be 35 and 16 °C. This study serves as a guide for future research focused on the thermoeconomic performance optimization of an ORC integrated into a natural gas engine.

Waste-heat recovery (WHR) systems based on the organic Rankine cycle (ORC) improve the thermal efficiency of natural gas engines because they generate additional electric power without consuming more gas fuel. However, to obtain a cost-effective design, thermoeconomic criteria must be considered to facilitate installation, operation, and penetration into real industrial contexts. Therefore, a thermo-economic analyses of a simple ORC (SORC), ORC with recuperator (RORC) and a double-pressure ORC (DORC) integrated with a 2 MW Jenbacher JMS 612 GS-N. L is presented using toluene as the organic working fluid. In addition, the cost rate balances for each system are presented in detail, with the analysis of some thermoeconomics indicator such as the relative cost difference, the exergoeconomic factor, and the cost rates of exergy destruction and exergy loss. The results reported opportunities to improve the thermoeconomic performance in the condenser and turbine, because the exergoeconomic factor for the condenser and the turbine were in the RORC (0.41 and 0.90), and DORC (0.99 and 0.99) respectively, which implies for the RORC configuration that 59% and 10% of the increase of the total cost of the system is caused by the exergy destruction of these devices. Also, the pumps present the higher values of relative cost difference and exergoeconomic factor for B1 (rk = 8.5, fk = 80%), B2 (rk = 8, fk = 85%).

WOS: 000460667700001, Science Citation Index Expanded, In the present study, a subcritical and supercritical regenerative organic Rankine cycle (rORC) was designed. The designed rORCs assist a combined heat and power (CHP) engine, the fuel of which is biogas produced from anaerobic digestion of domestic wastes in Belgium. R245fa was selected as the working fluid for both the subcritical and supercritical rORC. During the parametric optimisation, the net power production, mass flow rate, exchanged heat in the regenerator, total pump power consumption, thermal and exergetic efficiencies of rORC were calculated for varying turbine inlet temperatures and pressures. After parametric optimisation of the rORC, the results were compared with the results of the previous study, in which only a simple ORC is analysed and parametrically optimised. Moreover, the effect of the regenerator was revealed by examining all results together. Finally, the exergetic analysis of the best performing subcritical and supercritical rORC was performed. Furthermore, the results of the present and previous studies were considered together and it is clearly seen that the subcritical rORC shows the best performance. Consequently, by using the subcritical rORC, the disadvantages of the using simple ORC (low performance) and supercritical cycle (safety, investment) can be eliminated and system performance can be improved.

Energy planning and management in the built environment should not limit their scope to reaching zero-energy or nearly zero-energy balances: they should aim for cost optimality as well. Only then can environmental and economic sustainability be attained. In this study, a set of energy systems that include exchange with electrical and heating grids are proposed for an existing single-family house in Finland. The simulated energy and exergy balances are quantified, as well as the levelized cost of electricity and levelized cost of heat, the simple payback period and the internal rate of return of the investment. By driving a heat pump to convert surplus electricity into heat and exporting it, an annual energy surplus of 36 kWh/m2/a is achievable, whereas by importing heat from a heating grid leads to an annual exergy surplus of 8 kWh/m2/a. However, the economic indicators are unattractive: the lowest levelized cost of electricity and simple payback period are 41 cent/kWh and 46 years respectively, while the highest internal rate of return is 3.2%. Thus, the results indicate that reaching zero-energy balances in a cost-effective manner in single-family house under the current conditions in Finland is an arduous endeavour.

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.

Nowadays, gradual depletion of fossil fuels associated with emissions constraints due to greenhouse gases, leads to reuse wasted heat from power plant in order to increase the global efficiency. One of the implemented technologies for improvements is the application of combined cycles. In this scenario, the steam cycle is frequently combined with a Brayton cycle and the power plant performances and costs are competitive in the global market. Often, an energetic engineering company defines and studies the performance of the bottom steam cycle, thus it imposes operational conditions of steam turbine and heat recovery boiler and requires these components are built by two different manufacturers. For this reason, the plant cannot be globally optimized. From a steam turbines manufacturer point of view, the integration between proprietary simulation code and an energy balance code is an opportunity to simulate a complete bottom-cycle in order to define the best plant configuration. In the present paper, aone-pressure level heat recovery steam generator is studied in term of thermodynamic performance and cost analysis. The thermodynamic analysis is realized using a fixed steam turbine isentropic efficiency (as an energetic engineering company can do) and using anisentropic efficiency determined from steam turbine industrial tool, so a different best performance can be determined. Moreover, a comparison between two academic steam turbine cost correlations and steam turbine cost suggested by industrial cost is carried out.

Energy storage is regarded as a key factor to allow significant increase in the percentage of electricity generation from renewables. One of the most critical aspects related with energy storage is its economic feasibility, which intrinsically involves the analysis of the off-design conditions and the evaluation of the operating strategies using proper methodologies. This paper considers a promising system for mechanical energy storage constituted by a Compressed Air Energy Storage (CAES) integrated with a Hybrid Power Plant (HPP) and coupled with a wind farm. This system is modeled considering the South of Italy as the possible location. The HPP-CAES is simulated to operate on the Italian Power Exchange market, for one year, implementing suitable selling strategies. Cost analysis is performed using a thermoeconomic approach. Results show that reduced operating hours and large variations in the electricity production of the wind farm make the HPP-CAES cost-effective only when it is operated with the goal of solving local imbalances of the grid.

In this study, a novel thermoeconomic optimization method that is simple and efficient, for real complex cycles is introduced. First, a thermoeconomic analysis method that is called non-linear simplex direct search method is improved for the purposes of this study. The objective of this paper is to apply this method to four cogeneration cycles that are simple cycle, inlet air cooling cycle, air preheated and air-fuel preheated cycles for analyzing and optimizing. The four cycles are thermoeconomically optimized for constant power and steam mass (30MW and 14kg/s saturated steam flow rate at 2000kPa), for constant power (30MW) and for variable steam mass, and for variable power and steam mass by using the cost equation method and the effect of size on equipment method. The results obtained by the effect of size on equipment and by the cost equations methods are very different from each other. For the case of global optimization, the optimum electricity costs which also correspond to minimum are obtained as 0,0432$/kWh for simple cycle, 0,0514$/kWh for inlet air cooling cycle 0,0577$/kWh for air preheated cycle and 0,058$/kWh for air-fuel preheated cycle by using cost equations method. © 2014 Elsevier Ltd.

This paper presents thermodynamic and thermoeconomic analyses as well as optimization of a re-compression supercritical CO2 cycle. A gas turbine cycle (GT) is adapted as a model to an existing plant to generate additional power in Gaziantep Municipal Solid Waste Power Plant (GMSWPP). The total capital cost rate and total cost rate of the GT cycle are found to be 20.47 $/h and 77.14 $/h, respectively utilizing SPECO by using the exhaust gas of 16 kg/s with 1.9 bar and 566.7 degrees c. The net power, the energy and exergy efficiencies, the total cost and the total capital cost rates of the GT cycle are optimized by +1.73%, +3.21%, +2.45%, -1.11% and -1.64%, respectively using NSGA-II in MATLAB in the range of 2.5

In this work the results of the research made to PVC production plant reactors cooling system are included. The heat generated in the reactor must be removed to maintain its temperature at an optimal range between 50 and 70 °C. To assess the cooling system exergetic and Thermoeconomic indicators were used and it was observed that: (i) The greatest exergetic efficiencies arise in compressors. (ii) The greatest destruction of exergy and reasons of destruction of exergy cost and lower exergoeconomic factors are presented in the evaporative condenser. (iii) The heat exchange equipment has highest relative cost differences. © 2018 ASME. ASME

Energy simulation tools have a major role in the assessment of building energy retrofit (BER) measures. Exergoeconomic analysis and optimisation is a common practice in sectors such as the power generation and chemical processes, aiding engineers to obtain more energy-efficient and cost-effective energy systems designs. ExRET-Opt, a retrofit-oriented modular-based dynamic simulation framework has been developed by embedding a comprehensive exergy/exergoeconomic calculation method into a typical open-source building energy simulation tool (EnergyPlus). The aim of this paper is to show the decomposition of ExRET-Opt by presenting modules, submodules and subroutines used for the framework's development as well as verify the outputs with existing research data. In addition, the possibility to perform multi-objective optimisation analysis based on genetic-algorithms combined with multi-criteria decision making methods was included within the simulation framework. This addition could potentiate BER design teams to perform quick exergy/exergoeconomic optimisation, in order to find opportunities for thermodynamic improvements along the building's active and passive energy systems. The enhanced simulation framework is tested using a primary school building as a case study. Results demonstrate that the proposed simulation framework provide users with thermodynamic efficient and cost-effective designs, even under tight thermodynamic and economic constraints, suggesting its use in everyday BER practice.

The goal of the current article is to suggest a novel solar system to produce power, fresh water, and cooling. As solar energy is unavailable at nights, a novel thermal storage system (TES) based on phase change material (PCM) is used to store the required energy for night demands. The main novelty of the current configuration for the PCM is on the dynamic modelling of the PCM to capture the performance of the system during a day and perform the exergoeconomic analysis. After receiving the solar energy, a gas turbine and a Kalina cycle would supply the electricity of the grid. Additionally, the cooling capacity would be provided by the LNG stream for the domestic users, while reverse osmosis (RO) unit would produce the fresh water. To examine the performance of the system, the output parameters of the exergoeconomic analysis in addition to exergy destructions for each sub-system are computed. The output results indicate that the exergy efficiency is about 21.19%, while that of the energy is 41.00%. The cooling load of the suggested system is also 0.709 MW, while the rate of generated electricity and fresh water are 5.73 MW and 7905.7 m3/day, respectively. The exergoeconomic analysis also showed that the total cost rate of the system is equal to 25.20 $/GJ, and the levelized cost of electricity is 0.1275 $/kWh. Moreover, the impacts of input parameters on the respective output parameters are analyzed and optimized to reach the best performance of the system. Results indicated that the gas turbine’s pressure ratio should be approximately 8, while the needed values for the basic ammonia concentration and LNG pressure ratio are about 0.53 and 8.23, respectively.

A new combined cogeneration system for producing electrical power and pure water is proposed and analyzed from the viewpoints of thermodynamics and economics. The system uses geothermal energy as a heat source and consists of a Kalina cycle, a LiBr/H 2 O heat transformer and a water purification system. A parametric study is carried out in order to investigate the effects on system performance of the turbine inlet pressure and the evaporator exit temperature. For the proposed system, the first and second law efficiencies are found to be in the ranges of 16%–18.2% and 61.9%–69.1%, respectively. For a geothermal water stream with a mass flow rate of 89 kg/s and a temperature of 124 °C, the maximum production rate for pure water is found to be 0.367 kg/s.

In the last decades, thermoeconomic analysis emerged as a combination of exergy analysis and cost accounting principles, widely used for multiple purposes: to account for the exergy and economic costs of energy systems products, to derive the structures of such costs for the design optimization purpose, and to perform system diagnosis quantifying the source and the impact of malfunctions and dysfunctions within the analyzed process. Traditionally, thermoeconomic analysis is referred to as Exergy Cost Analysis or Exergoeconomic Cost Analysis. The former is based on the so-called Exergy Cost Theory, focused on the evaluation of exergy cost of the system products, while the latter is focused on the evaluation of monetary cost following the same theory. Currently, many practical approaches are available in the literature for the application of thermoeconomic analysis and Exergy Cost Theory to energy conversion systems, while a comprehensive classification, benchmarking and comparison of such approaches is missing. This paper aims to fill this gap through the following activities: first of all, a brief but comprehensive literature review related to the theoretical developments and applications of thermoeconomic analysis method is performed. Secondly and for the purpose of benchmarking, the main practical approaches identified for the application of Exergy Cost Theory are presented and formalized, including the fundamental aspects related to the definition of auxiliary relations and the reallocation of the exergy cost of the residues. Finally, the identified approaches are comparatively applied to the standard CGAM problem, and the advantages and drawbacks of each approach are discussed. It is found that the definition of the functional diagram and the numerical solution of the system through input-output analysis seem to be more straightforward with respect to the other approaches, leading also to the formalization of an unambiguous method to reallocate the exergy cost of the residual flows.

Direct steam generation in parabolic-trough collectors is considered a promising option for reducing the cost of electricity produced in solar thermal power plants. Indeed, the use of water instead of thermal oil allows reaching high temperature levels and reducing plant complexity. Furthermore, the integration of thermal energy storage system and the hybridization of the plant with a biomass boiler permit further cost reduction. This paper focuses on the historical and technological development of the direct steam generation concept and the thermoeconomic analysis of a hybrid direct steam generation-biomass power plant equipped with a thermal energy storage system. The exergy balance and cost balance equations have been applied to each component of the plant in four different operating modes that take into account the intermittency of the solar source. Exergy results show that the solar field requires further development in order to reduce associated irreversibilities. Finally, it was found that the integration of a thermal energy storage system and hybridization with a biomass boiler reduce the final cost of electricity to 17.36c€/kW he.

The paper describes a systematic framework that uses exergoeconomic theory integrated into ‘building energy retrofit’ (BER) design. An exergoeconomic module, based on the SPECO method, has been embedded into ‘EXRETOpt’, a recently developed retrofit-oriented exergy simulation tool based on EnergyPlus. Both active and passive technologies were analysed using two calibrated archetype non-domestic buildings as case studies (an office and a primary school). A novel cost-benefit indicator which accounts for building exergy destruction cost, retrofit annual capital cost, and project annual revenue is presented. This indicator is employed to account for best exergoeconomic performance technologies and to further develop deep BER packages. Compared to typical practice, exergoeconomics combined with cost-benefit provides a powerful tool for exploration and design improvement of building energy systems. In both cases, final product cost for heating and cooling processes were substantially reduced. In addition, the office case presented improvements in energy use by 67%, CO2 emissions by 53%, thermal comfort by 22%, exergy destructions by 42%, and the overall building exergy efficiency was improved from 14.8% to 20.0%. The school case presented similar results with an improvement of building exergy efficiency from 8.2% to 11.1%, and the potential to generate income due to current government incentives.

In this paper a thermoeconomic approach is applied to the dynamic model of a Power System in order to investigate the effects of the control system on the primary energy consumption and on the economic costs of the product. To achieve this objective, various control strategies are compared when variations of the operation condition, due to some internal or external causes, are produced. These variations cause the intervention of the control system, which rearranges the operating condition in order to have the controlled quantities within acceptable ranges. Generally the plant efficiency changes, depending on the selected strategy. A microturbine is considered as the case study. The analysis here proposed allows one to quantify the effect of the control on the performance variation of the components. The approach associates an exergetic cost and a thermoeconomic cost to the control system operation, which expresses the additional resource (primary energy and economic resources) consumptions that may be associated to the control. The impact on the initial and final steady states as well as the transient evolution are considered. This can be usefully applied to improve energy system operation acting on the control system, both in the off-design steady states and transient operations. In the particular application considered in this paper, reductions of about 8% in fuel consumption and 5% in the total costs are achieved. Concerning transient operation, it is shown that the control system can produce large variation in the operation costs.

International audience; Exergy analysis has been shown to be an efficient tool for understanding and improvement of industrial processes. In the present study, exergy analysis has been used to examine the energy consumption of an existing Steam Methane Reforming (SMR) process and then to test for possible savings in primary energy consumption and environmental protection. In the first step, energy and exergy balances of a steam methane reforming process were established to identify the thermodynamic imperfections of the process. Recommendations from this study have contributed to the building of a new and more efficient process. Consequently, a heat exchanger, corresponding to 44.9% of the total required area for the SMR heat exchange, has been incorporated in the SMR for waste heat recovery. The thermal and exergetic efficiencies of the original process are 70% and 65.5%, respectively. For the new process, the thermal and exergetic efficiencies are 74% and 69.1%, respectively. The unused exergy is reduced by 9.3% from 125.9 to 114.2 kJ per mole of H-2 produced. One mole of methane produces 2.48 mol of H-2 compared to 2.35 mol of H-2 produced in the original process. Furthermore, the new SMR process produces the lower greenhouse gas emissions

Made available in DSpace on 2019-09-12T16:53:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2010 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) This work develops a methodology for the determination of costs associated to products generated in a small wastewater treatment station. The methodology begins with plant units identification, relating their fluid and thermodynamics features to each point indicated in its process diagram. Following, a functional diagram and a formulation are developed in exergetic basis, describing all equations for these points, which are the constraints for optimisation and are used to determine costs associated to products generated in a Small Wastewater Treatment Station - SWTS. The methodology is applied to a hypothetical system based on SWTS plants and presents consistent results when compared to values based on previous experiments and evaluations. (c) 2010 Elsevier Ltd. All rights reserved. [Lamas, Wendell de Queiroz; Oscare Giacaglia, Giorgio Eugenio] Universidade de Taubaté (Unitau), Postgrad Programme Mech Engn, Dept Mech Engn, BR-12060440 Taubate, SP, Brazil [Lamas, Wendell de Queiroz; Silveira, Jose Luz; Mattos dos Reis, Luiz Octavio] Sao Paulo State Univ, Postgrad Programme Mech Engn, Fac Engn, Sao Paulo, Brazil

This paper presents a research project carried out by TPG (Thermochemical Power Group) of University of Genoa to develop innovative monitoring and diagnostics procedures and software tools for software-aided maintenance and customer support. This work is concerned with preliminary outcomes regarding the thermoeconomic monitoring of the bottoming cycle of a combined cycle power plant, using real historical data. The software is able to calculate functional exergy flows ( y ), their related costs ( c ) (using the plant functional diagram); after that non dimensional parameters for the characteristic exergonomic indexes (Δ c , Δ c *, Δ k *) are determined. Through a plant optimization (not described here) the reference conditions of the plant at each operating condition can be determined. Then, non dimensional indexes related to each thermoeconomic parameter are defined, in order to depict a “cost degradation”, and thus a significant rise in the production cost of the main products of the bottoming cycle (steam and power). The methodology developed has been successfully applied to historical logged data of an existing 400 MW power plant, showing the capabilities in estimating the “cost degradation” of the elements of the BC over the plant life, and trends in the thermoeconomic indexes.

Made available in DSpace on 2019-09-12T16:53:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2009 This work describes a methodology developed for determination of costs associated to products generated in a small wastewater treatment station for sanitary wastewater from a university campus. This methodology begins with plant component units identification, relating their fluid and thermodynamics features for each point marked in its process diagram. Following, its functional diagram is developed and its formulation is elaborated, in exergetic base, describing all equations for these points, which are the constraints for exergetic production cost problem and are used in equations to determine the costs associated to products generated in SWTS. This methodology was applied to a hypothetical system based on SWTS former parts and presented consistent results when compared to expected values based on previous exergetic expertise. (C) 2008 Elsevier Ltd. All rights reserved. [Lamas, Wendell Q.; Silveira, Jose L.] Sao Paulo State Univ, Dept Energy, Fac Engn, Postgrad Programme Mech Engn, BR-12516410 Guaratingueta, SP, Brazil [Lamas, Wendell Q.; Giacaglia, Giorgio E. O.; Reis, Luiz O. M.] Universidade de Taubaté (Unitau), Dept Mech Engn, Postgrad Programme Mech Engn, BR-12060440 Taubate, SP, Brazil

This paper aims at showing the capabilities of thermoeconomic analysis for solving cost assessments in district heating systems both at user and producer sides. In the near future it is expected that multiple producers are allowed to supply heat to the same district heating network, similarly to what happens in the case of the electric grid. Not only the amount of heat they may produce should be properly accounted, but also its quality, and also the pumping power that is requested to supply a unity of thermal energy to the end-users. Moreover, buildings equipped with low temperature heating system allow better use of the thermal energy vector, thus allowing larger efficiency of thermal plants. In the present work, the use of thermoeconomics for the analysis of these aspects is proposed. The approach allows one performing cost assessment in district heating, taking into account the effects of investment and operating costs and thermodynamic irreversibilities in the cost formation of heat from its production in the plants to its use in the buildings. Simple examples are analyzed in order to provide a quantitative evaluation of the various cost terms, depending on the operating conditions, topology and characteristics of the users/producers.

This paper presents the development of an exergy and thermoeconomic analysis of a wheat flour agro-industrial plant, which was aimed to evaluate the energy use and establish the operation cost of its components, and to understand the cost formation process and the cost flow. It was found that throughout the production process exists an exergy destruction ratio of 95,08 %. It identified improvement opportunities in relation to cost, has recommended alterations with regard matter flows or an economic investment for change some components with low exergoeconomic factors: 2% planer of wheat bran, 3% knurled roller grinding benches and 5% smooth roller grinding benches. Copyright © 2015 by ASME. American Society of Mechanical Engineers (ASME)

The necessity of air-conditioning causes the enormous energy use of underground train stations. Exergy and thermoeconomic analysis is applied to the annual operation of the air-conditioning system of a large underground train station in Taiwan. The current installation and the monitored data are taken to be the base case, which is then compared to three different optimized designs. The total revenue requirement levelized cost rate and the total exergy destruction rate are used to evaluate the merits. The results show that the cost optimization objective would obtain a lower total revenue requirement levelized cost rate, but at the expense of a higher total exergy destruction rate. Optimization of thermodynamic efficiency, however, leads to a lower total exergy destruction rate, but would increase the total revenue requirement levelized cost rate significantly. It has been shown that multi-objective optimization would result in a small marginal increase in total revenue requirement levelized cost rate, but achieve a significantly lower total exergy destruction rate. Results in terms of the normalized total revenue requirement levelized cost rate and the normalized total exergy destruction rate are also presented. It has been shown by second law analysis when applied to underground train stations that lower annual energy use and lower CO2 emissions can be achieved.

A novel solar power plant concept is presented, based on the use of a coupled network of hybrid solar-dish micro gas-turbines, driving a centralized heat recovery steam generator and steam-cycle, thereby seeking to combine the high efficiency of the solar dish collector with a combined-cycle power block. A 150 MWe solar power plant was designed based on this concept and compared with both a conventional combined-cycle power plant and a hybrid solar-tower combined-cycle. The solar dish combined-cycle power plant could reach higher levels of solar integration than other concepts but was shown to be more expensive with current technology; solar electricity costs are double those of the hybrid solar-tower combined cycle.

This article presents the exergoeconomic evaluation of a new geothermal-based integrated system, which produces hydrogen and freshwater. The proton exchange membrane electrolyzer (PEME) and humidifier-dehumidifier (HDH) units are responsible for hydrogen and freshwater production, respectively. Kalina cycle and thermoelectric generator (TEG) provide the needed electricity to run the PEME. As both TEG and HDH work with low-temperature waste heat of the Kalina cycle and geothermal water, two different configurations for the suggested system are proposed, and evaluated by the exergoeconomic analysis. Levelized cost of evaluation (LCoE) also compares the suggested configurations with fossil fuel power plants, while the effects of various critical parameters of the system are evaluated in the parametric study. Since there are uncertainties about decision parameters, single- and multi-objective optimizations with properly defined objectives are performed to achieve the best performance in each operating mode. Optimization studies revealed that the optimal mode is superior in terms of exergy efficiency, freshwater cost, and hydrogen cost with the values of 22.49%, 2.94 $/m3 and 7.37 $/kg, respectively.