Exergoeconomic Analysis Method Research Articles

Evaluating the influence of H2O phase state on the performance of LNG oxy-fuel combustion power plant: Exergy and exergoeconomic analyses

Oxy-fuel combustion with H2O as diluent is regarded as one of the most promising technologies to realize the carbon capture process in power plants. The phase state of H2O has a significant influence on system performance. In this paper, a novel oxy-fuel combustion system with the utilization of liquefied natural gas (LNG) cold energy is proposed. The effect of H2O phase states for improving potential and economy of the system is quantified using the exergy and exergoeconomic analysis methods. Results show that an O2/water system operates better than an O2/steam system, achieving an overall exergy efficiency of 36.35%, which is 4.7% higher than that of the latter. In the O2/water system, 11.99% of the exergy destruction can be avoided; this is, considerably higher than the 8.79% avoidable exergy destruction in the O2/steam system. In terms of economic feasibility, the total investment in the O2/water system is 1.86×105$/h, which is distinctly lower than the 3.47×105$/h investment in the O2/steam system. Moreover, the avoidable total cost rate in the O2/water system exceeds 53.36%, which is significantly higher than the 33.61% proportion in the O2/steam system. These results reveal that water is more suitable than steam for moderating the combustion temperature in oxy-fuel systems in terms of economic feasibility and exergy efficiency. This study is anticipated to have a positive influence on the global transition to a low-carbon future.

Life cycle assessment and exergoeconomic analysis of the multi-generation system based on fuel cell for methanol, power, and heat production

The main purpose of present investigation is to evaluate a multi-generation process by Life Cycle Assessment (LCA) and exergoeconomic analysis methods. This integrated system is composed of Methanol Synthesis Process, Molten Carbonate Fuel Cell (MCFC), and Combined Heat and Power system.This exergy – based evaluation is comprised of three items: (1) exergy evaluation to assess the efficiency and performance of the multi-generation system, (2) exergoeconomic evaluation to express a relationship between overall costs and the performance of the hybrid system, (3) exergoenvironmental evaluation to present useful information about the mutual impact of the process’s performance and environmental conditions. By applying the exergoeconomic and exergoenvironmental analyses, The process simulation and exergetic evaluation are conducted by the Aspen HYSYS V 11 and MATLAB software, respectively.This configuration provides 271.7 kgmole/h pure methanol, 110,544 kW net power, and 65398.7 kgmole/h hot water (at 80 °C). The total exergy efficiency and destroyed exergy rate of this multi-generation configuration are obtained to be 58.4% and 128549 kW, respectively. About 41.28% of the total exergy destruction rate occurred in the MCFC. The results of exergoeconomic assessment illustrate that the highest overall cost is associated with MCFC (4836.87 $/h). In addition, the burner has the least value of exergoeconomic factor (1.47%). So, to improve the cost-effectivity of the system, the burner should be re-designed. According to the exergoenvironmental analysis, the greatest values of overall environmental impacts belonged to MCFC (4033.13 Pt/h) and burner (1501.99 Pt/h), respectively. Accordingly, to decline the negative environmental impacts of the system, the operating conditions of selected devices must be modified. Finally, the 3D sensitivity analyses for four main devices are implemented. By using this sensitivity evaluation, the thermodynamic parameters that need to be optimized are specified.

Advanced exergy and exergoeconomic analysis of an integrated system combining CO2 capture-storage and waste heat utilization processes

To solve the problem regarding the purification of coal syngas, a system that integrates the CO2 capture and storage process and the waste heat utilization processes is proposed herein and analyzed using advanced exergy and exergoeconomic analysis methods. The purpose is to obtain the distribution of the exergy destruction rate and the cost rate of each block in the integrated process. The total exergy efficiency of the system was found to be 17.56%. Moreover, the total exergy destruction was 36424 kW, of which the CO2 capture and storage process accounted for 43.15%, the organic Rankine cycle process accounted for 32.35%, and the absorption refrigeration cycle process accounted for 24.50%. The exergy destruction ratio of the whole system was 82.44%. In this process, the optimization of the blocks such as the distillation column, absorber, and Evaporator 2 is to be considered a priority. Advanced exergy and energy efficiency analysis can provide guidance for the optimization of system irreversibility and help to determine the improvement potential of each block. In addition, certain strategies are proposed for the improvement of each block on the basis of the results, which can provide a theoretical flowchart for the efficient operation of the integration process.

Theoretical study on a modified single‐stage autocascade refrigeration cycle with auxiliary phase separator

Abstract In order to improve the cycle performance of a conventional single-stage autocascade refrigeration cycle (ARC), an auxiliary separator is considered to be introduced. In the modified autocascade refrigeration cycle (MARC), the auxiliary separator located after an expansion device is used to further collect the vapor enriched with low-boiling components. In this case, the MARC enables to improve the cycle performances by utilizing more zeotropic mixture enriched with the low-boiling components to realize a higher evaporation pressure at the given evaporation temperature in the evaporator of the cycle. The performances of the MARC and ARC are compared utilizing energy, exergy and exergo-economic analysis methods, and several important parameters are also discussed in detail. The results indicate that the MARC using zeotropic mixture R290/R170 is feasible and there are obvious improvements in terms of the COP, volumetric refrigeration capacity and exergy efficiency. It is found that compared to the ARC, the COP improvement of MARC can reach up to 16.1%. The exergy efficiency of MARC is increased by 10.23% and the overall cost rate of MARC is decreased by 2.51% under a typical operating condition. In addition, the COP of MARC has a maximum value at given conditions when the mass fraction of R290 at the compressor inlet is around 0.3. In general, the performance characteristics of the proposed cycle demonstrate its potential applications in low-temperature freezers.

Performance Evaluation of an Ironmaking System with Environmental Costs

This paper proposes an exergoeconomic analysis method that considers environmental costs to make up for the lack of description of environmental costs in the traditional matrix model exergoeconomic analysis method. This method tracks the formation process of the product cost through life cycle and makes a useful exploration for revealing the true cost of the system product. According to actual needs, the principles for the construction of environmental emissions of products are proposed, and a detailed exergoeconomic analysis model is established by taking the iron smelting system as an example. Through calculation and analysis, the formation process and change rule of unit exergoeconomic cost of products in the system are revealed. Especially, considering the exergoeconomic cost of carbon emissions, the results show that the three most influential substances are sinter, coke, and pellets. When carbon dioxide emissions are considered, the total cost will increase by 165.3 CNY/t iron, and unit exergoeconomic cost gradually increases with the progress of the production process.

Exergo-economic analysis method and optimization of a novel photovoltaic/thermal solar-assisted hybrid combined cooling, heating and power system

This study integrates concentrated photovoltaic/thermal (PV/T) solar collectors into a natural gas combined cooling, heating and power (CCHP) system to both offer efficient use of solar energy and reduce greenhouse emissions. Using exergo-economic analysis based on energy level, an optimization method was proposed and used to configure and determine the PV coverage ratio on the PV/T collector for minimizing the products’ costs of the hybrid CCHP system. The optimization method considers the users’ annual variable energy loads and transforms the off-design operation conditions to the design parameters by employing the heat storage ratio of thermal storage tank and supplemental heat ratio of absorption heat pump. Based on the validated thermodynamic modeling, an exergy and exergo-economic analysis of the hybrid CCHP system are presented to reveal the influences of the PV/T configuration on the exergy efficiency and the products’ cost. As the PV coverage ratio on the PV/T collector was increased, it was found that the specific cost of the CCHP system-generated electricity rose and then slightly dropped, while the specific cost of the heat exergy decreased, and then slightly increased. The optimal coverage ratio, at which the minimal specific cost of the system products was attained, had a value of 1.0. The integration and optimization of the PV/T decreases the specific cost of the system products by 6.4%. Compared to the conventional exergo-economics analysis method, the specific cost of system electricity using the exergo-economic analysis based on energy level is 20.3% higher, and the costs of heat exergy are decreased.

Exergoeconomic analysis for crude oil gathering and transportation system in matrix pattern

AbstractBased on exergoeconomic theory, the energy consumption situation for a typical oil transfer station in eastern China is evaluated. According to the analysis of the distribution for logistics and exergy flow, the crude oil gathering and transportation system is divided into two subsystems: pipe network and oil transfer station. The unit exergoeconomic costs for each component exergy flow are calculated by computing method in matrix pattern, of which the pressure exergy and thermal exergy at the end of the process are 812.58 yuan/GJ and 1575.24 yuan/GJ, respectively. Simultaneously, exergoeconomic evaluation indicators such as exergy cost growth coefficient, relative cost difference, and exergoeconomic coefficient are calculated, which can conclude the weak link of technical system is heating furnace equipment. The growth value of its exergy cost growth coefficient is 14.988, the relative cost difference is 94.503, and the exergoeconomic coefficient is 9.046, so it has great potential for energy saving. Exergoeconomic analysis method can provide a scientific and effective method or basis during the energy‐saving reconstruction for oil gathering and transportation system.

Experimental exergoeconomic performance assessment of a wastewater source heat pump system

This study aims at experimentally analysing and assessing the performance of a wastewater source heat pump system (WWSHP) in cooling mode, which was installed at Yasar University, Izmir, Turkey through exergetic and thermoeconomic (exergoeconomic) analysis methods. Within this context, first, conventional exergy analysis was performed based on the actual experimental data, where exergy efficiencies, destructions and relative irreversibilities of each element were determined to indicate improvements. Then, these results were combined with the cost data of the system to make exergoeconomic analysis. Functional exergy efficiencies of the entire system and the WWSHP were obtained to be 7.56% and 11.77%, respectively. The compressor had the biggest relative irreversibility, which was followed by the fan-coil. The exergoeconomic factor values of the condenser, WW heat exchanger (WWHE) and fan-coil unit were lower than 0.5, indicating that the exergy destruction costs associated with these components were higher than the capital investments.

Allocating the residues cost of a typical HTGR directly integrated with steam cycle using distributed entropy method

Exergetic cost theory (ECT) method, is a conventional exergoeconomic analysis method. In energy systems, disposing of remaining flows of matter or energy is called residues. Distributed entropy (DE) method is an important method for allocating the residues cost. In this study, ECT method and the DE method are applied to a high-temperature gas-cooled reactor (HTGR) that coupled with the steam cycle through the heat exchanger. Exergetic cost and exergoeconomic cost are obtained for each stream. Then residues cost distribution ratio is calculated by ECT and DE methods. The results have been compared with a model that is based on the disaggregation of physical exergy into its enthalpic and entropic terms which known as “H&S” model. The results show that DE method performed similar to the H&S model, but the DE method is a rational criterion to allocate the cost of the residues. The unit product cost of HTGR turbine and steam turbine are calculated as 0.2526 cents/kWh and 1.1500 cents/kWh, respectively. The maximum product unit exergoeconomic cost value is 3.1420 cents/kWh that is corresponding to steam cycle superheater.

Advanced exergoeconomic assessment of a solar-driven Kalina cycle

A Kalina cycle driven by solar energy resource is evaluated by conventional exergy and exergoeconomic analysis methods. Because conventional exergy analyses isn’t able to give information about costs of the irreversibilities and investment, advanced exergy is investigated. Based on the conventional exergy analyses, the most exergy destruction occurs in a heater with a value of 94.44 kW. Also the highest exergy efficiencies are related to the separator and turbine with the values of 99.67% and 89.81%, respectively. Advanced exergy analyses demonstrates absorber (1.3 $/h) and one of the pumps (0.009 $/h) have the highest and lowest exergy destruction cost rate, respectively. Also the results show turbine (85.88%) and separator (1.105%) have the highest and lowest exergoeconomic factor, respectively. Finally, in order to determine optimum point of the inlet temperatures and pressure ratio of the pumps and turbine (rotary machines), a parametric study is applied at different stages.

Advanced life cycle integrated exergoeconomic analysis of building heating systems: An application and proposing new indices

Advanced exergy-based analysis and assessment tools have been considered very useful tools for detecting the interactions among components of energy-conversion systems and the real potential for improving each component in any system. In this study, a building heating system is analyzed using advanced life cycle integrated (LCI)exergoeconomic analysis method, which combines cost and environmental impacts. Some new indices (metrics) such as advanced exergy destruction ratio, advanced LCIexergoeconomic ratio, advanced LCIexergoeconomic sustainability index and advanced indices are presented. These metrics are also applied to the main components of the system. The boiler has the maximum LCI endogenous exergy destruction cost ratio while the maximum LCI exogenous destruction ratio is due to the water heater. The advanced LCIexergoeconomic depletion ratios are 0.187, 0.599, 0.414 and 0.371 for the endogenous, exogenous, unavoidable and avoidable parts, respectively.

Modified exergoeconomic analysis method based on energy level with reliability consideration: Cost allocations in a biomass trigeneration system

Abstract 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.

Exergetic and exergoeconomic evaluation of an SOFC-Engine hybrid power generation system

An SOFC-Engine hybrid power generation system is evaluated using exergetic and exergoeconomic analysis methods to determine measures for improving its efficiency and cost effectiveness. The system is a combination of a solid oxide fuel cell (SOFC) and an internal combustion engine; the engine burns the anode offgas and produces additional power, thus improving the electrical efficiency of the overall system.The exergetic analysis, on the SOFC-Engine hybrid system, identifies the location, magnitude, and sources of thermodynamic inefficiencies (exergy destructions and exergy losses) in the system; the largest exergy destruction takes place within the internal combustion engine, followed by the heat exchangers, and the SOFC stack. Through the exergoeconomic analysis, the cost structure of the SOFC-Engine hybrid system is revealed, and the exergoeconomic factor of each component is quantified. The highest exergoeconomic factor of 93% is observed in the SOFC stack, implying that reducing the equipment cost of SOFC is of high importance to reduce the final product of the overall system. On the other hand, the fuel/water preheater shows the lowest exergoeconomic factor of 7%, meaning that improving its thermodynamic efficiency is more important for that component. Concerning the internal combustion engine, a well-balanced exergoeconomic factor of 52% is calculated.

Assessment of cost sources and improvement potentials of a ground-source heat pump food drying system through advanced exergoeconomic analysis method

Advanced exergoeconomic analysis, the so-called new exergetic approach combined with the economic analysis, is applied to a ground-source heap pump (GSHP) drying system in this study. The thermodynamic inefficiencies and cost performance of the system components are evaluated in parts. Moreover, the results of the advanced exergoeconomic analysis are compared to those of the conventional exergoeconomic analysis. The results show that total costs in the overall system are 4.008 $/h whereas 2.569 $/h of the total costs are avoidable. The avoidable investment costs are significantly lower than avoidable destruction costs. Advanced exergoeconomic analysis indicates that the most important system components are the drying duct and the condenser with respect to reducing the costs. It is possible to reduce 34.6% of the total costs by developing improvement strategies focused on the drying duct and the condenser. It may be concluded that the conventional exergoeconomic analysis is an effective approach to specify the components, in which costs are accumulated while the advanced exergoeconomic approach is essential to determine the cost sources and to develop cost effective improving strategies.

Advanced exergoeconomic analysis of a novel process for production of LNG by using a single effect absorption refrigeration cycle

A novel two refrigeration cycle process configuration for production of the liquefied natural gas is introduced and analyzed. In this process a single effect absorption refrigeration cycle which provides the refrigeration at −30°C is used as the precooling cycle. Coefficient of performance for this cycle is 0.49. The second cycle is a mixed refrigerant vapor compression refrigeration system. The results show that liquefaction efficiency is 0.20 kW hkg LNG. This process is analyzed and compared with the conventional propane precooled mixed refrigerant (C3MR) process. Next conventional and advanced exergoeconomic analysis methods are used to evaluate the modified process. Based on the exergoeconomic factor values, compressors and air coolers investment costs should be considered for improvement of the process. Endogenous exergy destruction in all of the process components is higher than the exogenous. Results of the splitting of exergy destruction costs indicate that avoidable exogenous destruction portion is very small.

Performance assessment of an ice rink refrigeration system through advanced exergoeconomic analysis method

Advanced exergy analysis has gained great importance as a comprehensive evaluation tool for energy conversion systems in recent years. In this regard, splitting the exergy destruction into avoidable/unavoidable parts has enabled us to identify the improvement potential of component while endogenous/exogenous parts of the exergy destruction have been detailed studied to get more information about interactions among the components. An ice rink refrigeration system was investigated using both conventional and advanced exergoeconomic analyses in this paper. The ice rink refrigeration system has a cooling load of 300kW and ammonia was chosen as refrigerant. Exergy destruction, investment cost rates and exergy destruction cost rates based on these two analyses were calculated first. Endogenous/exogenous and avoidable/unavoidable parts of the exergy destruction, investment cost rates and exergy destruction cost rate for each system component were then presented. Finally, possible solutions to reducing inefficiencies were discussed. It was determined that 47.15% of the total exergy destruction of the system was avoidable while 22.89% of the total exergy destruction of the system was exogenous. The evaporator with 18% endogenous available investment cost rate and the condenser with 64.3% endogenous available exergy destruction cost rate were the two most important components in the ice rink refrigeration system.

Exergoeconomic analysis of integrated natural gas liquids (NGL) and liquefied natural gas (LNG) processes

An integrated natural gas liquids (NGL) and liquefied natural gas (LNG) processes is investigated by exergy and exergoeconomic analysis methods. Exergoeconomic analysis parameters like exergoeconomic factor and relative cost difference of the process components are calculated and discussed. The highest exergy efficiency is related to the air coolers. Also multi stream heat exchangers exergy efficiencies is higher than 91%. C-1, C-9 and C-6 compressors, with 83%, 82% and 82% respectively are the components with high exergy efficiency. Exergy destruction in the compressors affect the required power in the process directly, so reduction of it can decreases the operating costs significantly. The greatest exergoeconomic factor is related to compressor (C9) (92.92%). Demethanizer column has small exergoeconomic factor and big exergy destruction. So column efficiency should be increased even though it increases the initial investment cost.

Advanced low exergoeconomic (ALEXERGO) assessment of a building along with its heating system at various stages

The present study deals with evaluating the performance of a building heating system along with its main components using advanced low exergoeconomic analysis method. This method combines advanced exergoeconomic with low exergy (LowEx) and is shortly called ALEXERGO. A building heating system is investigated from the energy production to the building envelope stage by stage through the ALEXERGO for the first time by the authors. Based on the results, the generation and distribution stages are found to have bigger exogenous exergy destruction cost rates, meaning that the components in these stages have strong interconnections. The emission (heating) stage has, however, a bigger endogenous exergy destruction cost rate. The generation and emission stages have low improvement potentials while the distribution stage has a big improvement potential. A sensitivity analysis is also made based on the environmental temperature for exergy destruction rates and efficiencies.

A Parametric Study of a Piston-Prop Aircraft Engine Using Exergy and Exergoeconomic Analysis Methods

In this study, exergetic and exergoeconomic analysis methods are applied to a four-cylinder, spark ignition (SI), naturally aspirated and air-cooled piston-prop aircraft engine in the cruise phase of flight operations. The duration of cruise is selected to be 1 h. Three parameters, altitude, rated power setting (PS), and air-to-fuel ratio (AF), are varied by the calculation of the max–min values of exergy analysis. Based on the results of energy analysis, the values for the maximum energy efficiency and fuel consumption flow rate are calculated to be 21.73% and 28.02 kg/h, respectively, at 1000-m altitude and 75% PS. The results of exergy analysis indicate that all exergetic values vary from 65% to 75% PS, while this increase is not seen in exergoeconomic analysis. While the maximum exergy input rate is obtained to be 405.60 kW, exergy efficiency has the minimum value with 14.43% and exergy destruction rate has the maximum value with 168.48 kW. These values are achieved at 3000-m altitude and 18 AFs. The maximum average exergy cost of the fuel is calculated to be 130.77 $/GJ at 1000-m altitude, 13 AF ratios, and 65% PS. At this point, while the minimum cost rate associated with the exergy destruction is obtained to be 40.29 $/h, the maximum exergoeconomic factor is found to be 19.98%.

Exergoeconomic analysis of energy utilization of drying process in a ceramic production

Thermo economic cost analysis of a ceramic plant, with a yearly production capacity of 24 million m2, was performed based on the actual operational data. The ceramic drying system was analyzed at the spray dryer, the vertical dryer and the furnace stages. The performances of these three processes and the effects of the process conditions on the process performance were evaluated using energetic, exergetic, and exergoeconomic analysis methods. The performance assessment was performed through energy and exergy efficiencies, the improvement potential rate, the total cost, and the exergoeconomic factor terms. The ratio of the thermodynamic loss rate to the capital cost values was obtained in the range of 53.38–135.83 MW/$. In this process, there is a great potential towards increasing the energy and exergy utilization efficiencies.