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Cogeneration is considered as one of the promising energy efficient techniques for producing electricity and useful thermal energy from a single fuel source. This paper describes a feasibility study of the implementation of different cogeneration options to a paper mill to evaluate their energy saving potentials and economic benefits. The investigated systems in this paper are gas turbine, steam turbine and combined cycle cogeneration options evaluated and compared based on energy utilisation factor and Annualised Life Cycle Cost (ALCC) analysis. The results of energy analysis show that all Combined Heat and Power (CHP) systems satisfy the thermal energy needs of the mill while the combined cycle cogeneration option generates the highest amount of electric energy equal to 10.91 MW. The gas turbine cogeneration system is shown as the most advantageous system from overall energy point of view with the highest energy utilisation factor of 78% meeting the heat and electric requirements of the mill and exporting 21,329 MWh of additional electricity to the grid. Economic feasibility results also show that an overall saving of 5.12 million US$ can be achieved by implementing the gas turbine cogeneration system to the mill making it as the best cogeneration option with the least overall ALCC of 1.34 million US$ and the maximum percentage of CO 2 emission reduction (68%) when compared with the other options. [ABSTRACT FROM AUTHOR]

Abstract Professor Jan Szargut was one of the world pioneer of exergy analysis and his adventure with exergy going back to its beginnings in world science. His subsequent and significant contribution to the field of exergy analysis is certainly not to be overestimated. Within the paper a short overview of Professor Szargut activity is presented. One of the important application of exergy analysis proposed by Szargut is the Thermo-Ecological Cost (TEC) let to connect exergy and ecology. The general theory and algorithm of TEC is presented in the paper. The potential results obtained using TEC are presented based on trigeneration system, nuclear power plant and metallurgical process. Finally, the pro-ecological tax is described. Highlights • A brief history of Professor Szargut activities. • Thermo-Ecological Cost (TEC) as example of ecological application of exergy analysis. • TEC of combined cooling, heating and power system. • TEC of nuclear power plant. • TEC of blast furnace system. [ABSTRACT FROM AUTHOR]

Highlights • In gas turbines analysis no ideal vs perfect gas comparisons exist in literature. • A highly accurate ideal gas model for gas turbines analysis is presented. • Accuracy of perfect gas model in gas turbines depends on the cycle's configuration. • A given specific heat evaluation rule affects performance parameters differently. • Maximum relative errors up to 19% are found when perfect gas model is used. Abstract The ideal gas model with temperature-independent heat capacities is the most widely used thermodynamic model in gas turbine cycle simulations. This model is sometimes known as the "perfect gas model". Closed analytical expressions for specific works and temperatures of the cycle are obtained in this way. If the results are accurate enough then the perfect gas model becomes a powerful analysis tool because its simplicity. For this reason it is the usually chosen option when energy, exergy or thermoeconomic assessments and optimizations of gas turbine cycles are carried out. However, there is a shortage of research works about the analysis of the uncertainty in the calculation of the performance parameters of open-cycle gas turbines with respect to the ideal gas model-based approach (ideal gas with temperature-dependent heat capacities). This analysis is presented in this paper for the simple cycle taking the net specific work output or specific power of the cycle and its Specific Fuel Consumption (SFC) as the performance parameters to be analyzed. First, to gain in internal coherence, an accurate thermodynamic model of the simple cycle based on the ideal gas assumption with temperature-dependent heat capacities is presented. For the sake of accuracy the isobaric heat capacity functions used in this model for every gaseous component present in the cycle are the employed in developing its actual multiparameter equations of state as real fluids. Once this model is established the perfect gas simplification is applied which requires a procedure or rule to evaluate the constant heat capacity values needed. In many cases this rule is not always given or is not clearly specified in the specific literature. In this paper four different evaluation methods (named as A, B, C and D) are considered. These methods are designed to be directly run from known input fixed parameters of the cycle model. The analysis of the absolute and relative errors in computations with the perfect gas approach with the four heat capacity evaluation methods is then carried out. The main result from the analysis is that the own configuration of the open-cycle can lead to an increase (amplification) of the uncertainty in the values of the performance parameters. It is also observed that: (1) this amplification also depends on the method used to evaluate the heat capacities and (2) for a given evaluation method the amplification of the deviations may affect the performance parameters differently. As an example, maximum relative errors of 4.4% and −19.2% are observed in the net specific work output with methods C and D respectively for compressor pressure ratios from 5:1 to 40:1 and turbine inlet temperatures from 1200 K to 1800 K. For the SFC maximum values are −19.51% with method C and 3.95% with method D. [ABSTRACT FROM AUTHOR]

The present paper tackles the issue of allocating economic costs in trigeneration systems including thermal energy storage (TES) for buildings of the residential-commercial sector. As energy systems become more and more complex (multiple resources, products and technologies; joint production; TES) the issue of the appropriate way to allocate the cost of the resources consumed arises. This is important because the way in which allocation is made directly affects the prices of the products obtained and, thus, the consumers' behavior. Thermoeconomics has been used to explain the cost formation process in complex energy systems. In this paper, two issues in thermoeconomics that have not been deeply studied are addressed: (i) the joint production of energy services in dynamic energy systems; and (ii) the incorporation of TES. A thermoeconomic analysis of a simple trigeneration system including TES was performed and the hourly unit costs of the internal flows and final products were obtained for a day of the year. The cost allocation proposal considered that the cogenerated products must share the benefits of the joint production. Regarding the TES, the interconnection between charging and discharging periods was explored, allowing the discharged energy flow to be traced back to its production period. [ABSTRACT FROM AUTHOR]

Assessing system costs for power generation is essential for evaluating the economical aspect of energy resources. This paper examines traditional and renewable energy resources under uncertainty and variability of input variables. The levelized cost of electricity (LCOE) of each technology is computed using a global sensitivity analysis. A Monte Carlo approach is utilized to study the thermoeconomics of a variety of power generation methods in the United States: fossil fuel-based, nuclear, developed renewable, and emerging renewable energy resources. The results of this study demonstrate how uncertainties in input data can significantly influence the LCOE values. Power generation from well-developed energy technologies exhibit less variability in LCOE due to established capital costs, operating and maintenance costs, and power generation. On the contrary, emerging renewable energy technologies are subject to high uncertainties in both technical and economic performance, as expected for technologies in early stages of development. A scenario with carbon pricing in power generation is also carried out in the paper. The presence of carbon pricing significantly increases the LCOEs of fossil fuel technologies, and LCOEs of other technologies also experience significant changes when life-cycle carbon assessments are considered. Several cost reduction opportunities are discussed to guide the development of future energy conversion, especially from emerging renewable energy resources. [ABSTRACT FROM AUTHOR]

This paper presents thermodynamic and thermoeconomic analyses as well as optimization of a re-compression supercritical CO 2 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 °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 ≤ P R ≤ 4 , 200 ≤ P 6 ≤ 216 , 16 ≤ T 0 ≤ 23 and 9.1 ≤ L M T D ≤ 12.9 . This paper provides an originality such that optimization as well as thermodynamic and thermoeconomic analyses is performed simultaneously for an existing MSW power plant, which can be stressed that there are scarce amounts of studies related on this field. Moreover, as another novelty, it can be emphasized that net power output of such like plants which have similar capacity can be improved using the developed model and NSGA-II optimization method. [ABSTRACT FROM AUTHOR]

Current study aims in finding the combined effect of using rectangular fins, gravels (G) and phase change material (PCM) on the performance of pyramid solar still. Two solar stills, one of conventional type (CSS) and other of modified solar still (MSS) which uses fins and PCM inside the basin, are fabricated. Experiments are conducted at Greater Noida (28°28′N, 77°30′E) of Uttar Pradesh, India, during May 2023. The influence of solar still design modifications (CSS and MSS) and adding gravels (CSS + G and MSS + G) on the performance of solar stills is investigated in terms of productivity, energy, exergy, economic, and environmental parameters. Experimental results show an enhancement of about 84 %, 38 % and 32 % in daily productivity for MSS + G, CSS + G and MSS, respectively, than CSS. The MSS + G shows the highest improvement in energy (81.1 %) and exergy efficiency (273 %) with significant reduction in costs per liter of yield produced (29.2 %) and payback period (29 %) when compared with CSS. About 76 % rise in carbon credits earned is observed for MSS + G than CSS while mitigating the CO 2 emission of 19.14 tons. Conclusively, the innovative design (MSS + G) not only offers cost-effective yield production but also plays a crucial role in promoting environmental sustainability by reducing CO 2 emissions. • This paper develops and tests a modified solar still that uses PCM and fins. • The combined effect of fins, gravels and PCM is investigated. • The experiments conducted in Greater Noida, India, during May 2023. • MSS + G improved daily productivity by 84 %. • MSS + G reduces costs/l of water by 29 % and mitigates CO 2 emissions by 19.14 tons. [ABSTRACT FROM AUTHOR]

Concerning the building environment HVAC facilities, even if a great effort has been made in developing components and systems with high nominal efficiencies, less attention has been paid to the problem of system maintenance. The main objective of the thermoeconomic diagnosis is to detect possible anomalies and their location inside a component of the energy system. The second objective, and indeed the one to be achieved in this paper, is indicated as inverse problem. It is associated with the quantification of the effects of anomalies in terms of thermoeconomic quantities. Its rigorous application in building thermal installations has some difficulties relating to the strong interrelation between the different components and the fact that energy supply facilities are continuously changing with time. The way to deal with dynamic circumstances is thoroughly explored in this article. Likewise, this paper’s main goal is to demonstrate an application of two thermoeconomic diagnosis methodologies in the building sector, one based on the malfunction and dysfunction analysis and the other one based on the characteristic curves of the components. The results obtained allow us to point out the advantages and limitations of both methodologies as well as to combine them and then develop a more reliable diagnosis. [ABSTRACT FROM AUTHOR]

Integration of thermal systems improves the energy efficiency and reduces the carbon emissions. In this paper, a novel trigeneration system, which integrates the organic Rankine cycle and vapor compression–absorption cascade refrigeration cycle is proposed. The cascade refrigeration system combines the advantages of the conventional stand-alone vapor compression system and vapor absorption refrigeration system. The energetic and rational efficiencies of the proposed system, with n-pentane as an ORC working fluid, are calculated as 79.02% and 46.7%, respectively. Effects of variation in different operating parameters as well as organic working fluid on energetic and exergetic efficiencies have been studied. The coefficient of structural bond analysis demonstrates that the evaporator and cascade condenser operating temperature significantly affects the system performance. The proposed trigeneration system powered by waste heat is independent of the grid supply; however, a stand-alone vapor compression refrigeration system requires about 19.15 kWe to meet the equivalent cooling demand. The decision of selection between the stand-alone system and the proposed trigeneration system is influenced by the compressor capacity of stand-alone vapor compression refrigeration system, cost of unit electricity, compressor runtime, cost of organic Rankine cycle power block, and cost of vapor absorption system. Based on the condition of equality of the annualized cost of the stand-alone system and proposed trigeneration system, a methodology for selection between these two configurations, called selection diagram, is also presented in this paper. The selection diagram gives quick suggestion about the optimal configuration at the initial design stage. The economic analysis reveals that the simple payback period and breakeven point for the proposed hybrid system are 6.2 years and 4.9 years, respectively. [ABSTRACT FROM AUTHOR]

This paper presents a detailed numerical analysis of a trigeneration system serving a hospital, aiming at determining the best economic operating strategy. In this paper, a novel approach is presented aiming at developing a detailed tool to be used to predict the real time performance of the trigeneration system and to optimize its operation designing efficient control strategy. To this scope, a detailed dynamic simulation model was developed in TRNSYS environment. The simulated system provides electrical, thermal and cooling energy. It includes: a natural gas fired reciprocating engine, heat exchangers for waste-heat recovery, a single-stage LiBr-H 2 O Absorption Chiller (ACH), a cooling tower, pumps, a backup boiler, a backup vapor-compression electric chiller, storage tanks, valves, mixers. For such components, suitable control strategies and detailed algorithms were implemented in order to develop a model as much realistic as possible. To this scope, cooling and thermal loads were estimated by implementing detailed building dynamic simulations strictly related to the trigeneration system model. Three different operating strategies were evaluated in order to minimize the plant cost and maximize the performance of the system, namely: Thermal Load Tracking mode (TLT), Maximum Power Thermal Load Tracking mode (MPTLT) and Electricity Load Tracking mode (ELT). In the first one (MPTLT), the thermal power provided by the engine is always lower or equal to the thermal demand; in the second one (TLT), the engine operates according to an On/Off strategy; in the third one (ELT), the electrical power provided by the engine is always lower or equal to the electrical demand. The results of the case study were presented on different time bases (days, weeks, years). Such results show that the ELT control strategy can achieve a better profitability, with a simple payback period, SPB, equal to 4 years. For this strategy, 256 simulations were also performed by varying the main model parameters, in order to determine the combination showing the lowest SPB value and the highest Primary Energy Saving (PES) value. The optimum and the analysis of the optimum response surface was obtained by using Design of Experiments (DoE) method, showing that the best SPB value, equal to 3.9 years, comes out choosing an engine capacity ratio equal to 1, an ACH capacity ratio equal to 1, a hot tank volume equal to 5 m 3 and a cold tank volume equal to 2 m 3 . The best PES value, instead, is equal to 20.6% and comes out selecting an engine capacity ratio equal to 0.5, an ACH capacity ratio equal to 1, a hot tank volume equal to 6 m 3 and a cold tank volume equal to 2 m 3 . [ABSTRACT FROM AUTHOR]

Biophysical Economics is a school of thought in heterodox economics built on the premise of the primacy of energy in the economic process. Despite significant progress made in the methodology of net-energy analysis, the literature on the relationships (if any) between the biophysical properties of energy sources, such as net-energy ratios, and financial indicators (price, cost, etc.) is scant. Are the biophysical qualities of energy sources reflected by market signals? As such, can the latter guide decision-making in the context of the ongoing depletion of non-renewable energy resources? The paper examines the relationships between the net-energy ratios and price, cost of production and price-to-cost ratios of the Canadian oil sands produced via open-pit mining from 1997 to 2016. A simple econometric model is developed to estimate the correlation between the standard Energy Return on Energy Invested (EROIst) with the price, cost of production and price-to-cost ratio of diluted bitumen and synthetic crude over a 20-year period. Preliminary results suggest the absence of correlation between any pair of biophysical and financial variables. No discernable correlation is identified between the EROIst and financial indicators of either crude stream, suggesting biophysical and financial properties to be sui generis realities. [ABSTRACT FROM AUTHOR]

This paper goes through a sophisticated ecological function for irreversible regenerative closed Brayton cycle. Moreover, aforementioned irreversible regenerative closed Brayton cycle is optimized by implementing ecological function. With the aim of the first and second laws of thermodynamics, an equivalent system is initially specified. Developed multi objective evolutionary approaches (MOEAs) on the basis of NSGA-II method is implemented throughout this work. To accomplish the above mentioned target of this paper, three objective functions which includes the power output ( P ), the ecological function ( E ) and thermoeconomic criterion ( F ) are perceived in optimization process simultaneously. Three aforementioned objective functions are maximized at the same time. [ABSTRACT FROM AUTHOR]

The paper presents a novel concept for thermodynamic evaluation of a selected energy system. The presented method has been developed by integration of the Thermo-Economic Analysis with the theory of Thermo-Ecological Cost. It can be applied as a thermodynamic evaluation method of rational resources management within any production system. It takes into account both the interrelation of irreversibility within the analyzed system and its influence on the global effects related to the depletion of non-renewable natural resources. The proposed method has been applied to evaluate the production of electricity in the process of natural gas transmission at pressure reduction stations. The expansion system is based on an existing plant integrated with a CHP module, characterized by a performance ratio of 89.5% and exergy efficiency of 49.2%. Within the paper, this expansion plant is supplied with natural gas transported from a natural deposit through a case-study transmission system with 4 compressor stations. The TEC (thermoecological cost) method was applied in conjunction with thermoeconomic analysis. As a result, TEC of the electricity generated in the expanders was determined at 2.42 kJ/kJ, TEC of electricity from the CHP module is 1.77, and the TEC of medium-pressure natural gas distributed to consumers is 1.022. [ABSTRACT FROM AUTHOR]

In ecological economics, natural resources – which may contribute only a small amount to GDP – are viewed as fundamental to the functioning of the economy. They are sometimes pictured as sitting at the base of an inverted pyramid, with the rest of the economy balanced on top of them. In this paper we show that when prices are set by markup, a standard heterodox assumption, then the “inverted pyramid” picture of the economy emerges naturally in a neo-Ricardian model. We demonstrate the use of the model with brief applications to biophysical economics. The paper is one of a growing number that use heterodox macroeconomics to address questions in ecological economics. [ABSTRACT FROM AUTHOR]

Hybrid photovoltaic/thermal collectors (PVT) consist of common photovoltaic modules cooled by a suitable fluid, and convert solar radiation simultaneously into both thermal and electric energy. The heat transfer between PV cells and fluid allows to reduce the temperature of the PV cells; this improves the electrical efficiency, but also makes available low-grade heat for specific applications. As a consequence, PVT modules show a very interesting overall energy efficiency. In this paper, the Second Law analysis of a water-cooled PVT collector is presented, based on simulations. The study also discusses a crucial problem for the optimal exploitation of this technology: the electricity production from PV cells is favoured by low temperatures, whereas the usability of the thermal energy gets higher at high temperatures. The paper demonstrates that, for any operating condition, it is possible to calculate an optimum water inlet temperature that maximizes the total exergy generated by the system. The optimum temperature falls within the range commonly occurring in solar thermal systems, and can be achieved in practice through a simple control-command system. Finally, a thermoeconomic analysis is carried out to define the price of the thermal energy produced by the PVT collector, as a function of its exergy content. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a new technique is proposed for design and optimization of a heliostat field. The unique aspect of the proposed approach is the code's ability to design the field with non-equal heliostats. It has been argued that designing a field of non-equal heliostats improves the energy and economic performance of a heliostat field. On this account, a new code called AINEH (analysis of implementation of non-equal heliostats) was developed to evaluate this idea. Firstly, the mathematical models developed in AINEH code are discussed by presenting the initial layout model, expansion technique, economic model, optimization approach, and objectives. Parametric analysis is carried out to identify the effect of different design parameters. Additionally, AINEH code is used to re-design PS10 by conducting a thermo-economic optimization. Energy optimization results show that PS10 annual weighted efficiency can be improved by 0.32% points from 68.91% to 69.23% in case of using AINEH code. In addition, field's levelized cost of energy (LCOE) can be reduced by 1.3 US$/MWh (6.5%) from 19.9 US$/MWh to 18.6 US$/MWh. Graphical abstract Image 1 Highlights • A new heliostat field design and optimization technique is proposed. • The proposed method designs and optimizes fields with non-equal heliostats. • The code is used to redesign PS10 by conducting a thermoeconomic optimization. • Parametric analysis is conducted to study the effect of different design variables. [ABSTRACT FROM AUTHOR]

Highlights • Rigorous evaluation of the circularity, impacts and limits of circular economy systems. • Simulation-based assessment of the copper section of the Metal Wheel. • Circular economy limitations demonstrated with a complete flow sheet from ore to metal. • Simulation-based exergy, thermoeconomics and LCA evaluation performed with HSC Sim. • Material recovery, residues generated and losses predicted through the simulation. Abstract The transition from a Linear to Circular Economy has become a societal challenge to be tackled. However, the increasing complexity of materials and products increases also the sophistication of the circular economy systems required to deal with them. These systems are very resource consuming, therefore, a rigorous evaluation of the impact of every "actor" in circular economy must be done at design and operation stages to ensure the sustainability of the metal-production value chain. A circular economy system implies, among others, low consumption of energy and material resources and low production of wastes or pollutant emissions. Its sustainability cannot therefore be evaluated just with one indicator. In this paper, we integrate indicators such as recovery rates, environmental impact indicators, as well as the quantities and qualities of the flows, losses and emissions, quantified through exergy. These must all be considered and evaluated simultaneously to perform a rigorous sustainability analysis. The challenges of achieving a circular processing system and society are illustrated using a unique copper flowsheet that covers the complete processing chain from ore to refined metal including among others minor elements refining, scrap recycling, residue processing, steam utilization, sulphur capture and power generation in 129 unit operations linked by 289 streams and all the compositional and thermochemical detail. Using a simulation-based approach, two scenarios have been studied and compared: (i) a representative primary copper flowsheet and (ii) excluding all waste treatment processes. This unique simulated flowsheet permits a complete evaluation of various scenarios of all copper related processing options (while any additional unit operations can also be added) and also rigorously permits an allocation of impacts of all flows, products, residues etc. as a function of the complete mineral composition. This approach to evaluating systems shows how to estimate the true losses from a system and will be a key approach to evaluate the true circularity of the circular economy system. [ABSTRACT FROM AUTHOR]

Highlights • The thermodynamic and thermo-economic models of SORC and DORC are built. • The thermodynamic and thermo-economic performances are optimized and compared. • The DORC can increase power output and show better thermo-economic performance. Abstract The goal of this paper is to study and evaluate the thermodynamic and the thermo-economic performance of dual-pressure and single pressure evaporation organic Rankine cycle (DORC and SORC) using isobutane as the working fluid. The effects of the two-stage pressures and the heat source inlet temperature on the system performances have been investigated. Then the performance comparisons between SORC and DORC have been conducted at the optimized condition. Results show that the DORC yields more net power than the SORC when the heat source temperature is between 100 and 177.2 °C, and the net power output gains of the DORC are higher at lower heat source temperature. The DORC no longer has the performance advantage as the heat source temperature is above 177.2 °C. The thermo-economic evaluations show that the optimized electricity production cost (EPC) decreases as the heat source temperature rises. Furthermore, optimized EPC of SORC and DORC are nearly equal at the same heat source temperature. For the heat source temperature of 100–177.2 °C, the DORC can significantly increase the net power output, but the thermo-economic performance of DORC is not reduced by system complexity compared to the SORC. [ABSTRACT FROM AUTHOR]

Highlights • Sabatier-based CO 2 methanation plant modelling and simulation. • Plant optimization through Pinch Analysis. • Sabatier conversion yield improvement. • Thermoeconomic analysis and identification of critical plant components. • Sensitivity analysis of electricity cost, CO 2 emission trades and CO 2 sequestration costs on methane cost. Abstract The present global energy scenario has to face the technical and economic challenges of the global CO 2 emissions mitigation. The two main technological paths followed are on one hand the increase of renewable share and on the other the implementation of carbon capturing and storage solutions. While the main drawback of the first one is the need to include an energy storage to compensate for the fluctuations of the sources, the one of the latter is related to the high CO 2 sequestration costs. Sabatier based power-to-gas systems are potential answers for both the above described issues. Object of this paper is the modelling, process design and simulation of a CO 2 methanation plant based on the Sabatier reaction. Since the main issue of power-to-methane storage technology is its low overall conversion efficiency, the pinch analysis approach has been applied to enhance the energy recovery that represents a key factor in the increase of the plant global efficiency. An exergy and thermoeconomic analysis of the proposed plant was performed in order to evaluate the main sources of irreversibility and to calculate the CH 4 production costs as a function of the main plant parameters. A Sabatier conversion yield of 93.48% has been obtained producing 0.42 kg of CH 4 per each kg of captured CO 2 with an improved cost of 53 €/MWh. The results of the study have shown the great potentials of this solution as an "energy storage" and CO 2 capture facility. [ABSTRACT FROM AUTHOR]

Abstract The wider adoption of organic Rankine cycle (ORC) technology for power generation or cogeneration from renewable or recovered waste-heat in many applications can be facilitated by improved thermodynamic performance, but also reduced investment costs. In this context, it is suggested that the further development of ORC power systems should be guided by combined thermoeconomic assessments that can capture directly the trade-offs between performace and cost with the aim of proposing solutions with high resource-use efficiency and, importantly, improved economic viability. This paper couples, for the first time, the computer-aided molecular design (CAMD) of the ORC working-fluid based on the statistical associating fluid theory (SAFT)-γ Mie equation of state with thermodynamic modelling and optimisation, in addition to heat-exchanger sizing models, component cost correlations and thermoeconomic assessments. The resulting CAMD-ORC framework presents a novel and powerful approach with extended capabilities that allows the thermodynamic optimisation of the ORC system and working fluid to be performed in a single step, thus removing subjective and pre-emptive screening criteria that exist in conventional approaches, while also extending to include cost considerations relating to the resulting optimal systems. Following validation, the proposed framework is used to identify optimal cycles and working fluids over a wide range of conditions characterised by three different heat-source cases with temperatures of 150 °C, 250 °C and 350 °C, corresponding to small- to medium-scale applications. In each case, the optimal combination of ORC system design and working fluid is identified, and the corresponding capital costs are evaluated. It is found that fluids with low specific-investment costs (SIC) are different to those that maximise the power output. The fluids with the lowest SIC are isoheptane, 2-pentene and 2-heptene, with SICs of £5620, £2760 and £2070 per kW respectively, and corresponding power outputs of 32.9 kW, 136.6 kW and 213.9 kW. Highlights • Thermoeconomic CAMD-ORC framework developed with component sizing and cost correlations. • Validated for novel cycles (partial evaporation, mixtures) and applied to 150, 250, 350 °C heat sources. • Minimising SIC identifies different fluids compared to thermodynamic optimisation. • Optimal SICs of £5620, £2760 and £2070 per kW are identified for 150, 250 and 350 °C, respectively. • Optimal fluids correspond to power outputs of 32.9, 136.6 and 213.9 kW. [ABSTRACT FROM AUTHOR]

In this work, a dynamic model of a high-temperature integrated solar combined cycle power plant is presented. The system includes a three-pressure combined cycle power plant coupled to parabolic trough solar collectors. Thermal storage, a heat solar steam generator, pumps, heat exchangers, and several controllers are also included in the system. Solar energy is used to produce additional steam to be supplied to the steam turbine of the combined cycle power plant. The integrated solar combined cycle system is based on the heat transfer fluid arrangement, exploiting solar energy to produce steam. The analysis is developed by a dynamic simulation model including detailed algorithms for the calculation of the performances of system components. Special control strategies are included in the model in order to accurately manage the steam production of the heat solar steam generator. The paper presents a thermo-economic and environmental comparison between the integrated solar combined cycle and a conventional combined cycle, powered by fossil fuels, based on dynamic simulations. A case study, referred to a plant with a maximum power of around 100 MW, located in Almeria (Southern Spain), is presented and discussed. A parametric analysis was also performed to show the effect of the variation of total solar field reflector area on the system performance. For the case under evaluation, a simple pay-back of 15 years was found, for a solar field aperture area of 80 000 m 2 ; however, the parametric analysis suggests that a smallest solar field area should be used under the hypotheses of the case study. [ABSTRACT FROM AUTHOR]

This paper presents the parametric optimization and performance analysis of the organic Rankine cycle (ORC) system for waste heat recovery from marine engine exhaust. The engine exhaust heat under operating conditions has been field-measured and evaluated. The thermo-economic optimization based on multi-objective evaluations is conducted numerically. This study aims to determine the optimal design evaporation temperature and condensation temperature, and to select suitable working fluids. The cooling water loop is taken into accounted for the whole ORC system. The parametric optimization with objective functions is compared. The economic objective function is defined as the ratio of net power output to total heat exchanger area, and the comprehensive objective function is determined as the weight-sum of exergy efficiency and economic objective function. The results show that there is the optimal evaporation temperature under the fixed expansion ratio in the ORC system for achieving the maximum thermal efficiency. The optimal condensation temperature for achieving the maximum economic objective function or comprehensive objective function is determined respectively. The parametric optimization with comprehensive objective function is better. With multi-objective evaluations, R141b performs the most satisfactorily with the maximum net power output of 97 kW, followed by R113 and cyclohexane, and R600a performs the least favorably. The optimized ORC system with R141b under various operating conditions is technically feasible and economically attractive. [ABSTRACT FROM AUTHOR]

This paper presents the design of a novel high-temperature solar assisted triple-pressure level combined cycle power plant. The system includes innovative high-temperature flat plate evacuated solar thermal collectors, a double stage lithium bromide/water absorption chiller, pumps, heat exchangers, storage tanks, mixers, diverters, controllers and a triple-pressure combined cycle power plant. This novel layout uses high-vacuum non-concentrating flat plate solar thermal collectors driving a double effect absorption chiller, leading to an overall high coefficient of performance for the solar cooling section. The provided cooling energy is used to cool gas turbine inlet air to enhance system efficiency and electrical capacity. This effect is mainly performed during central hours of the day when the conventional gas-fired combined cycles dramatically suffer for efficiency and capacity reduction, as a consequence of the corresponding increase of external air temperature. Such increase is related to the higher availability of solar radiation. This technology may be a viable solution, especially for hot and dry areas, in terms of primary energy savings and increased revenues. This prototypal system was numerically analysed for a combined cycle with a rated electrical power of 99 MWe and an electrical efficiency of 56%, developing a dynamic simulation model and detailed thermo-economic optimizations. Special attention is also paid to the design of novel control strategies aiming at maximizing the solar cooling effect. The results of the dynamic simulations show a very high average thermal efficiency of the solar collectors, equal to 34%. Implications of the performed work allowed an increase of the power output up to 5.5% and a satisfactory payback period equal to 10.7 years. [ABSTRACT FROM AUTHOR]

This paper proposes a modified exergoeconomic method based on energy level with reliability considerations to analyze the cost allocations in a biomass trigeneration system. Energy level is introduced to the exeregoeconomic method to agree with the principle of high energy level with high cost. The system reliability and availability using the combination of state-space and the Markov method is incorporated in the exergoeconomic method to analyze the cost changes for three products in the trigeneration system. The cost influences of failure rate, repair rate, biomass cost and annual operation time are examined to reveal the cost variations with reliability considerations. The cost allocation and sensitivity analysis are presented in a case study. The results indicate that the failure and repair rates of the gasification system largely influences the cost of products from the electricity generation system and the cooling system. The specific exergy cost of the three products with reliability consideration increases approximately 16%. The reduced operation uptime due to component's or subsystem's failure is the key parameter to decrease the revenue at the certain investment and increase the risk cost. [ABSTRACT FROM AUTHOR]

In this paper, a solar double absorption heat transformer (SDAHT) operating with the LiBr-H 2 O solution is proposed to provide high temperature energy. The flat plate collector (FPC) is used to supply the demanded heat input in the present configuration, which will greatly broaden the application scope of the FPCs. The thermoeconomic concept is applied to the evaluation and optimization of the SDAHT, aimed at minimizing its annual capital cost per kilowatt heat capacity ( CPK ) and payback period ( PP ). A dedicated computer model in the software Engineering Equation Solver was developed to conduct the study by means of a parametric analysis. The results show that there exists an optimum absorber/evaporator temperature at which CPK and PP can obtain the minimum values. With solar radiation intensity at 600 W/m 2 , generation (evaporation) temperature at 75 °C, condensation temperature at 38 °C, absorption temperature at 135 °C and economizer efficiency set to 0.8, the optimum absorber/evaporator temperature and corresponding CPK and PP are 104.0 °C, 928.1 euros/kW and 4.0 years, respectively. The cost of the FPCs takes the major part of CPK . Moreover, the effects of the operating parameters such as the generation (evaporation), condensation, absorption temperatures and design parameters including the first and second economizer efficiencies on the optimum absorber/evaporator temperature and corresponding CPK and PP have been analyzed in detail. Besides, some suggestions derived from the results are also given to assist the engineers in estimation of the economic performance. [ABSTRACT FROM AUTHOR]

Solar energy is a promising option for reducing both energy consumption and harmful gas emissions. Seasonal thermal energy storage is a challenging key technology able to minimize the mismatch between the availability of the solar energy and the thermal energy demand. In this paper, a solar district heating system (basically composed of a solar collectors array, a short-term thermal energy storage (STTES), a long-term borehole thermal energy storage (BTES), an auxiliary natural gas-fired boiler and a heat distribution network) has been analysed by means of dynamic simulations over a 5-year period when serving a district composed of 6 typical single-family houses under the climatic conditions of Naples (center Italy). A sensitivity analysis has been carried out by simulating 27 configurations obtained by varying solar collectors area, volume of STTES and volume of BTES. The simulations results have been compared with those associated to a conventional heating system in terms of primary energy consumption, carbon dioxide equivalent emissions, operating costs as well as simple pay-back period in order to (i) evaluate the potential benefits, (ii) explore the influence of the components size on the system performance and (iii) establish some simple rules for the initial design of the main subsystems. [ABSTRACT FROM AUTHOR]

In present work thermoeconomic features of two different gas turbine power utility configurations, namely basic gas turbine cycle (BGT) and intercooled gas turbine cycle (IcGT) are presented and compared thermoeconomically. A computer code has been developed using various models comprises governing equations, in order to obtain the results for particular power utility and operating parameters. The analytical model also contains blade cooling phenomenon, which is described schematically in this paper. Among numerous thermoeconomic methodologies, the average cost theory approach has been adopted for the present investigation. The current work focuses on thermoeconomic comparison of power utilities based on above mentioned cycles. Also, the behavior of cycle performance parameters, with cycle operating parameters (compressor pressure ratio and turbine inlet temperature) of proposed cycle has been reported. Results obtained showed that IcGT based power utility requires 47.34% higher fuel during operation and delivers near about 40% higher plant specific work. The total cost rate of IcGT cycle is slightly higher in the base case parameters (compressor pressure ratio = 36, turbine inlet temperature = 1500 K, isentropic efficiency of compressor = 88% and isentropic efficiency of turbine = 90%) compared to BGT and at the same time it delivers lower electricity cost (2.872 cents/kWh), which is 28% less due to higher plant specific work. [ABSTRACT FROM AUTHOR]

One of the methods of gas turbine performance improvement is steam injection into combustion chamber. Moreover, heat recovery is introduced as another method for enhancing energy and exergy efficiencies. In this paper, these two methods were combined in a system of Integrated Heat Recovery Steam Injected Gas Turbine (IHRSI) equipped with an anti-surge system. A heat exchanger was used for waste heat recovery of the gas turbine exhaust and steam production. In these conditions, due to the energy balance in the HRSG, there was a relation between steam temperature and steam mass flow rate. One problem in IHRSI is determining optimum steam temperature. The increment of temperature decreases the steam mass flow rate and consequently has opposite effects on the various parameters. Therefore, in the present study, a comprehensive model based on the energy, exergy, environmental and economic analyses (4E) was presented. Eventually, the developed model introduced the optimum conditions of injected steam into combustion chamber. The optimum steam temperature of 318.5 °C was found in the case of 38 °C ambient temperature and 10% relative humidity. IHRSI at the optimum steam temperature increased net power output and thermal efficiency by 56 MW and 4.6% and reduced the cost of power generation by 25.5%. [ABSTRACT FROM AUTHOR]

A branch of finite-time thermodynamics (FTT) is the thermoeconomical analysis of simplified power plant models. The most studied models are those of the Curzon–Ahlborn (CA) and Novikov–Chambadal types. In the decade of 90’s of the past century, the FTT analysis of thermal engines was extended to chemical engines. In the present paper we made a thermoeconomical analysis of heat engines and chemical engines of the CA and Novikov types. This study is carried out for isothermal endoreversible chemical engine models with a linear mass transfer law and under three different modes of thermodynamic performance (maximum power, maximum ecological function and maximum efficient power). [ABSTRACT FROM AUTHOR]

The continuing depletion of fossil fuels and the growing restrictions for greenhouse emissions, leads to reprocess wasted heat generated by power plants. For this purpose, Combined Cycles Gas Turbine (CCGT) represent a strong technology to obtain, an increase of performances and competitive costs within global market. To design the CCGT configuration, energy engineering companies should define and analyze the performances of bottomer cycle, imposing operating parameters of steam turbine and heat recovery boiler. Usually, these plant components are supplied by different manufacturers so the plant could not be globally optimized. Considering a steam turbines manufacturer as GE Oil&Gas, a high level of components integration, is a chance to optimize globally the bottomer cycle, determining the best machine in terms of efficiency and improving plant productivity. This aim could be obtained through the development of a high level of combination between company simulation codes and energy balance codes. In this paper, a two-pressure level combined cycle is examined and optimized. The best thermoeconomic configuration is obtained: first, imposing steam turbine efficiency and using literature costs correlations; then, acquiring the efficiency by a steam turbine industrial tool and considering real machines costs. Therefore, two distinct best configurations could be determined and compared. [ABSTRACT FROM AUTHOR]

In the era of fast paced development, energy sector is also looking for methodologies which can diligently investigate the thermodynamics as well as economics of power utilities. The methodology need to be so designed that it is able to analyze the effect of operating parameters on plant performance and its costing. In this regard thermoeconomic investigation is a tool which combined thermodynamic concepts and economic principles to analyze thermal systems. Present paper deals with comparative thermoeconomic investigation of basic gas turbine (BGT) and intercooled recuperated gas turbine (IcRcGT) cycle based power utilities featuring air film cooling of turbine blades. The work also represents the effect of operating parameters on thermoeconomics of two aforesaid cycles. In present work Average-Cost-Theory approach has been adopted for the investigation. The results so obtained from calculation reports that IcRcGT offers 50% higher plant specific work with 27.8% higher fuel flow rate as compared to BGT for base case parameters (r pc = 30, TIT = 1500 K, η AC = 88% and η GT = 90%). The total cost rate for IcRcGT is 16.33% higher and at the same time related cost of electricity is 20% lower as compared to BGT for same operating parameters due to higher plant specific work. [ABSTRACT FROM AUTHOR]

Kalina cycle is a promising power cycle to utilize or recover the heat of low-grade heat sources. Most of previous works focused on the thermodynamic and thermoeconomic analysis or optimization for the cycle. In this paper, an off-design mathematical model for Kalina cycle is established to examine the off-design performance of the cycle with the variation of heat source mass flow rate, heat source temperature and cooling water temperature. A modified sliding pressure regulation method, which regulates the turbine inlet pressure to keep the temperature difference between heat source temperature and turbine inlet temperature constant, is applied to control the cycle when off-design conditions occur. The results show that the modified sliding pressure regulation method keeps Kalina cycle with a good off-design performance. With the increase of heat source mass flow rate or heat source temperate, both of the net power output and thermal efficiency increase. With the increase of cooling water temperature, both of the net power output and thermal efficiency decrease. In addition, the turbine efficiency almost keeps the designed value under the off-design conditions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this paper a thermoeconomic analysis of a novel hybrid Renewable Polygeneration System connected to a district heating and cooling network is presented. The plant is powered simultaneously by solar and geothermal sources, producing electricity, desalinated water, heat and cooling energy. System layout includes Parabolic Through Collector (PTC) field, geothermal wells, Organic Rankine Cycle (ORC) unit and a Multi-Effect Desalination (MED) system. Cooling and thermal demands are calculated by suitable building dynamic simulation models, calibrated for Pantelleria Island. Electrical demand is obtained by measured data. A detailed control strategy has been implemented in order to prevent any heat dissipation, to match the appropriate operating temperature levels in each component, to avoid a too low temperature of geothermal fluid reinjected in the wells and to manage the priority of space heating and cooling process. A 1-year dynamic simulation has been performed and results analyzed on daily, monthly and yearly basis. The system achieved an SPB equal to 8.50 and it resulted capable to cover the energy demands of a small community. Moreover, the plant is capable to cover the fresh water demand of the Pantelleria Island. [ABSTRACT FROM AUTHOR]

In this paper an exergy analysis and thermoeconomic cost accounting of a Combined Heat and Power steam cycle integrated with Multi Effect Distillation-Thermal Vapour Compression plant is performed; the goal of the study is to show how these methodologies provide a rational criterion to allocate production costs on electricity and freshwater in such a dual purpose system. After a brief overview on the methodology and a description of reference plant, exergy analysis is carried out to calculate exergy flows and exergy efficiencies at component level. A detailed description of the adopted thermoeconomic model is given. In a first scenario, cost accounting is performed assuming that the concentrated brine is disposed back to sea, thus being its exergy content definitively wasted; furthermore, a sensitivity analysis is carried out in order to assess the changes in the unit cost of electricity and freshwater with several design and operation parameters. In a second scenario, conversely, part of brine exergy is used in a Reverse Electrodialysis unit to produce further electricity. In both cases results show that high unit costs are obtained for the material streams or energy flows which involve major exergy destruction along their production process, particularly freshwater in the former configuration and Reverse Electrodialysis electric output in the latter one. [ABSTRACT FROM AUTHOR]

In this paper after thermo-economic modeling of a solar heater using flat plate collector, the system is optimized. For this purpose, six variables are selected as decision variables. Then Particle Swarm Optimization algorithm is applied to obtain the maximum efficiency and the minimum of the total annual cost as two objective functions. The results of optimal designs are a set of optimum points, named Pareto front. The trend of variation in both efficiency and total annual cost with change in decision variables is also performed and the results are discussed. Mass flow rate as well as insulator thickness are found as two important decision variables which cause a confliction between objective functions. On the other hand, collector length has no effect on the confliction. To generalize the optimum results, the optimization of the system is performed for the different rates of heat transfer. The results reveal that, the efficiency is relatively changed for 0.123%, −0.740% and −1.506%, respectively in the cases of 0.5 kW, 1.5 kW and 2 kW compared with the case of 1 kW. The above changes for the total annual cost are obtained 44.30%, −40.98% and −77.87% which verify the thermoeconomic improvement in the lower rate of heat transfer. [ABSTRACT FROM AUTHOR]

In this paper, a combined cooling, heating and power cycle is proposed consisting of three sections of gas turbine and heat recovery steam generator cycle, Regenerative organic Rankine cycle, and absorption refrigeration cycle. This trigeneration cycle is subjected to a thorough thermodynamic and exergoeconomic analysis. The principal goal followed in the investigation is to address the thermodynamic and exergoeconomic of a trigeneration cycle from a new prospective such that the economic and thermodynamic viability of incorporating Regenerative organic Rankine cycle, and absorption refrigeration cycle to the gas turbine and heat recovery steam generator cycle is being investigated. Thus, the cost-effectiveness of the introduced method can be studied and further examined. The results indicate that adding Regenerative organic Rankine cycle to gas turbine and heat recovery steam generator cycle leads to 2.5% increase and the addition of absorption refrigeration cycle to the gas turbine and heat recovery steam generator/ Regenerative Organic Rankine cycle would cause 0.75% increase in the exergetic efficiency of the entire cycle. Furthermore, from total investment cost of the trigeneration cycle, only 5.5% and 0.45% results from Regenerative organic Rankine cycle and absorption refrigeration cycles, respectively. [ABSTRACT FROM AUTHOR]

This paper presents the thermodynamic modeling of an organic Rankine cycle (ORC) that uses waste exhaust energy of a 1000 kW diesel generator on a naval ship. Seven different working fluids have been selected as the ORC fluids. The commercial software (EES) has been used to predict the thermodynamic properties of the selected fluids. The efficiency of the ORC goes up to 32% with toluene. For the needed generator power of 500 kW on cruising, the ideal ORC can produce 118 kW power with the working fluid toluene. Assuming an isentropic efficiency for the turbine and the pump of the case ORC to be 0.75 and 0.20, respectively, and neglecting the losses at the ORC electric generator, the electric power output of the ORC cycle becomes 92 kW. The power of the diesel-ORC system becomes 592 kW while the combined efficiency is calculated as 0.349. The ORC saves 25,500 L of diesel fuel (US$24,870) and reduces 67.2 tons of CO 2 emissions at the end of 1000 operating hours. ORC working fluids may result different efficiencies at different temperatures. Therefore, a combined ORC system is proposed to get higher efficiencies at different thermal loads. The exergy efficiencies and irreversibilities were calculated. [ABSTRACT FROM AUTHOR]

The search for optimal phase change materials (PCMs) for latent heat thermal energy storage systems (LHTESS) focuses almost exclusively on the properties of the PCM. This neglects the significant contribution of the cost of the containment vessel on the total cost of the LHTESS. Thus, to accurately assess the thermoeconomic performance of various PCMs, the relationship between the cost of the containment vessel and the properties of the PCM must be understood. This paper presents an analytical method for optimizing the design of tube and shell or tube and fin containment vessels for the least cost, subject to geometric and performance constraints. One of the key performance constraints is the time to charge, whose evaluation typically requires computationally-expensive simulations which are unsuitable for optimization algorithms. To enable efficient optimization, a novel closed-form approximation of the charge time is developed and validated through numerical simulations. Subsequently, the optimization methodology is used to investigate the relationship between the optimal vessel geometry and configuration, fin properties, PCM properties, and cost of two PCMs. For these PCMs, the use of high thermal conductivity fins is shown to dramatically reduce the total cost of the system. The new methodology is an efficient way to compare the thermoeconomic performance of PCMs as latent heat storage solutions, allowing for the accurate assessment of PCMs. [ABSTRACT FROM AUTHOR]

Escalating crude oil price and environmental problem are attracting more interest in methods to improve thermal efficiency and reduce emission of shipping. Comparatively, The Organic Rankine cycle (ORC) offers a good solution to utilize low-medium quality waste heat from marine engine. In this paper, an operational profile based thermal-economic evaluation model is established providing reliable evaluation on Organic Rankine cycle used for waste heat utilization from marine diesel engines. Base on this model, ORC system is proposed and designed based on the ship’s most typical operational condition. The effect of ship’s operating condition on ORC thermodynamic performance among seven working fluid candidates is analyzed. Thermal-economic analysis is presented with increasing attention to the ship’s operational profile based on the measurement data from 4-week navigation of objective passenger cruise ship. The result indicates that: considering the different thermodynamic properties, R123 is capable of outputting power at heavy load of engine, while R365mfc is more suitable at light load of engine. Taking typical operational profile into consideration, R123 suits better when ORC is designed for container ships, while R365mfc is suggested for bulk carrier and tankers. For the investigated case study, compared with estimation using nominal design output power, the electricity production cost EPC increased by around 36–41% when operational profile is included. Nominally, all working fluid candidates can satisfy 5-year payback limit except RC318. However, only R123, R365mfc and R245ca are feasible when operational profile is considered. This result makes clear that real operational profile is indispensable for assessing the feasibility of technology. [ABSTRACT FROM AUTHOR]

This paper presents a methodology to guide the design of heat exchangers for a steam generator in a solar power tower plant. The low terminal temperature difference, the high fluid temperatures and the high heat duty, compared to other typical shell and tube heat exchanger applications, made the design of the steam generator for molten-salt solar power towers a challenge from the thermomechanical point of view. Both the heat transfer and the thermal stress problems are considered to size the preheater, evaporator, superheater and reheater according to the TEMA standards and ASME Pressure Vessel code. An integral cost analysis on the steam generator design effects on the power plant performance reveals an extremely low value for the optimum evaporator pinch point temperature difference. Furthermore, an optimization using genetic algorithms is performed for each heat exchanger, which leads to economical and feasible designs. A 110 MWe solar power tower plant is studied. Two configurations of the steam generator are proposed: with one or two trains of heat exchangers. The results show that the optimum pinch point temperature differences are very close to 2.6 °C and 3 °C for the steam generator with one and two trains, respectively. The proposed design of the steam generator consists of a U-shell type for superheater and reheater, a TEMA E shell forced circulation evaporator and a TEMA-F shell preheater. Also, the approach point temperature difference analysis is performed to avoid subcooled flow boiling in the preheater. An economic study to compare forced and natural circulation evaporator designs is carried out. [ABSTRACT FROM AUTHOR]

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 h e . [ABSTRACT FROM AUTHOR]

The search for more efficient processes is mandatory in current society to save resources and avoid further environmental damages. Life Cycle Assessment, LCA, has become an important tool in evaluating the waste generated and resources necessary to produce a given product so that it can be compared with alternative products from energy and environmental points of view. In multiproduct energy systems, the allocation of resources and waste by methods traditionally utilized in LCA studies seems arbitrary. Thermoeconomic theories are well known for the rational allocation of waste and resources in multiproduct plants. This paper compares five allocation techniques usually applied in LCA studies with three thermoeconomic allocation techniques for pollutants (CO 2 , NO x and SO x ) and resources (fuel consumption). The comparison revealed that commonly applied methods for the allocation of emissions in LCA studies provided wide variation between results (over 88%). Thermoeconomic methods, in turn, provided less variation and yielded a more rational approach as the multiproduct step was disaggregated into its subsystems. Thermoeconomic approaches seem to be a perfect match to LCA when multiproduct systems have to be considered. Thus, merging thermoeconomics and LCA methodologies provides a deeper and more rational perspective for complex systems via an integrated analysis. [ABSTRACT FROM AUTHOR]

The paper is a complementary study of Food Yellow 4 and Food Blue 2 adsorption in single-compound and binary systems on modified chitosan (CC-chitosan), using statistical physics and Ideal Adsorbed Solution Theory (IAST) models. In order to provide new macroscopic interpretations of adsorption mechanisms, three thermodynamic functions were determined, such as configurationally entropy, free enthalpy and internal energy. The configurationally entropy trend showed that the dye molecules have plenty possibilities/positions to be docked on empty receptor sites at low concentrations, but limited possibilities at high equilibrium concentrations. The study of the free enthalpy and internal energy confirmed that the adsorption process in single-compound and binary systems is spontaneous. The second theoretical approach is based on the IAST model to predict the multicomponent adsorption isotherms using single-compound isotherm data. The IAST model provides a very good prediction of binary adsorption data, for both the adsorbates. Best results were obtained for Food Yellow 4 adsorption data; while for Food Blue 2 an increasing deviation between experimental and modeling binary adsorption data can be observed along with increasing concentration. Finally, the IAST model correctly described the decrease in adsorption capacity of both the dyes from single-compound to binary system, due to competition effects. [ABSTRACT FROM AUTHOR]

In this paper, a thermo-economic analysis of an Integrated Solar Regenerative Rankine Cycle (ISRRC) is performed. The ISRRC consists of a nanofluid-based Parabolic Trough Solar Collector (PTSC), and a Thermal Energy Storage System (TES) integrated with a Regenerative Rankine Cycle. The effect of dispersing metallic and non-metallic nanoparticles into conventional heating fluids on the output performance and cost of the ISRRC is studied for different volume fractions and for three modes of operation. The first mode assumes no storage, while the second and the third assume a storage system with a storage period of 7.5 h and 10 h respectively. For the modes of operation with the TES, the charging and discharging cycles are explained. The results show that the presence of the nanoparticles leads to an increase in the overall energy produced by the ISRRC for all modes of operation, causing a decrease in the Levelized Cost of Electricity (LEC), and an increase in the net savings of the ISRRC. After comparing the three modes of operation, it is established that the existence of a storage system leads to a higher power generation, and a lower LEC; however, the efficiency of the cycle drops. It is seen that the maximum increase in the annual energy output of the ISRRC caused by the addition of Cu nanoparticles to Syltherm 800 is approximately 3.1%, while the maximum increase in the net savings is about 2.4%. [ABSTRACT FROM AUTHOR]

Siloxanes are usually used in the high temperature organic Rankine cycle (ORC) for engine waste heat recovery, but their flammability limits the practical application. Besides, blending siloxanes with retardants often brings a great temperature glide, causing the large condensation heat and the reduction in net output power. In view of this, the zeotropic mixtures based on siloxanes used in a dual-loop organic Rankine cycle (DORC) system are proposed in this paper. Three kinds of binary zeotropic mixtures consisting of R123 and various siloxanes (octamethylcyclotetrasiloxane ‘D4’, octamethyltrisiloxane ‘MDM’, decamethyltetrasiloxane ‘MD2M’), represented by D4/R123, MDM/R123 and MD2M/R123, are selected as the working fluid of the high temperature (HT) cycle. Meanwhile, R123 is always used in the low temperature (LT) cycle. The net output power and utilization of heat source are considered as the evaluation indexes to select the optimal mixture ratios for further analysis. Based on the thermodynamic and economic model, net output power, thermal efficiency, exergy efficiency, exergy destruction and electricity production cost ( EPC ) of the DORC system using the selected mixtures have been investigated under different operating parameters. According to the results, the DORC based on D4/R123 (0.3/0.7) shows the best thermodynamic performance with the largest net power of 21.66 kW and the highest thermal efficiency of 22.84%. It also has the largest exergy efficiency of 48.6% and the smallest total exergy destruction of 19.64 kW. The DORC using MD2M/R123 (0.35/0.65) represents the most economic system with the smallest EPC of 0.603 $/kW h. Besides, the irreversibility in the internal heat exchanger, turbine and evaporator of HT cycle contributes most to the total exergy destruction which can serve as the parameter to be optimized in the further study. [ABSTRACT FROM AUTHOR]

Thermodynamic diagnostics aim to identify and act upon thermal system devices exhibiting abnormal behaviour (malfunctions) in order to later, through the use of maintenance routines, return the devices to their optimum operating condition. Several methods have been developed to solve the problem of thermal system thermodynamic diagnosis, all of which are designed to identify components exhibiting malfunctions and their effect on cycle power output and efficiency. Individually these methods have both advantages and disadvantages, with the complementary use of two or more providing better results. In this paper a diagnostic system is proposed for externally fired gas turbines (EFGT), using the thermoeconomic method in conjunction with artificial neural networks to identify malfunctioning components (intrinsic malfunctions) and their fuel impact. The concepts “Exergetic Operator” and “Transition Structure” are also presented. An EFGT was simulated using the commercial software GateCycle™ 5.51, aiming to reach a power of 99.80 kW (design point) using wood carbonisation residual gas as fuel. An ANN was developed with the commercial software MATLAB ® . [ABSTRACT FROM AUTHOR]

The cost of heat exchangers account for a large proportion of total investment in organic Rankine cycle (ORC). In this paper, plate heat exchanger (P), shell-and-tube heat exchanger (S) and finned-tube heat exchanger (F) are used as evaporator and condenser of four subcritical ORC configurations: ORC-PP, ORC-SS, ORC-FP and ORC-FS. The thermo-economic models are built and a thermo-economic evaluation and comparison of four ORC configurations is presented in order to recover the low-temperature waste heat. The optimal evaporating pressure, pinch point temperature difference, net power output and dynamic payback period corresponding to the minimum electricity production cost (EPC) are obtained for different ORC configurations under different heat source temperatures. Results show that the EPCs of ORC-PP and ORC-SS are apparently higher than that of ORC-FP and ORC-FS. Among them, ORC-FS is the most cost-effective configuration. The optimal pinch point temperature difference in evaporator has a decreasing trend with the increase of critical temperature of working fluid for ORC-FS and ORC-FP, while the optimal pinch point temperature difference in condenser keeps nearly constant. [ABSTRACT FROM AUTHOR]

Hybridization is a newly proposed concept in which solar thermal energy provides a portion of the required thermal input instead of fossil fuels and natural gases. Storage and intermittency concerns regarding solar energy make hybridization a viable solution to increase renewable energy share in power generation. Maisotsenko gas turbine cycle is a recently proposed humid air turbine cycle which can be implemented as a bottoming cycle to a topping gas turbine cycle as Maisotsenko bottoming cycle. In this paper, Maisotsenko bottoming cycle power plant hybridization is thoroughly investigated using heliostat field collector. First, a thermo-economic optimization is carried out for a hybrid Maisotsenko bottoming cycle power plant in the United Arab Emirates. Furthermore, the optimization results for Maisotsenko bottoming cycle are evaluated against the acquired results for hybrid air bottoming cycle and conventional combined cycle. Finally, different levels of hybridization are considered for an already existing non-hybrid Maisotsenko bottoming cycle power plant by applying different thermo-economic assessment methods. Comparative analyses indicate that Maisotsenko bottoming cycle is a more economical alternative for bottoming cycle implementation as compared with the other investigated configurations with optimum levelized cost of electricity of 75.330 US$/MW h. [ABSTRACT FROM AUTHOR]

This paper presents a novel process for high efficiency production of hydrogen and desalination of brine water based on the concept of solar spectrum splitting. The advantage of this system is concurrent production of hydrogen and distilled water using a sustainable process at large scale. The harvested energy from the separated solar spectral bands is used to supply the required energy for high temperature steam electrolysis and a double-stage flash distillation system. The integrated solar system is designed to reduce the energy conversion deficiencies, considerably. In order to investigate the performance of this system, a process simulation code is developed. An exergy analysis is conducted and the economic feasibility of the plant is evaluated. The sensitivity of the integrated cycle performance on solar insolation, electrolyzer temperature, and pressure is analyzed, and the results indicate that utilization of concentrator cells, with a multi-band gap mirror can increase the productivity of the cycle, drastically. It is observed that hydrogen and distilled water production rate can be increased by more than 1.6 times, when the harvested solar power increases from 28 MW to 55 MW. It is concluded that the maximum energy and exergy efficiencies of the integrated solar cycle is about 45%. [ABSTRACT FROM AUTHOR]