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[en] Highlights: • The overall energy and exergy efficiencies of the plant is found to be 59.37% and 38.99% respectively. • Performance assessment of a cement plant indicates that the calcination process involves the highest portion of energy losses. • The specific exergetic cost cement produced by the cement plant is calculated to be 180.5 USD/GJ. • The specific cement manufacturing cost is found to be 41.84 USD/ton. - Abstract: This paper is Part 2 of the study on the thermodynamic and exergoeconomic analysis of a cement plant. In Part 1, thermodynamic and exergoeconomic formulations and procedure for such a comprehensive analysis are provided while this paper provides an application of the developed formulation that considers an actual cement plant located in Gaziantep, Turkey. The overall energy and exergy efficiencies of the plant is found to be 59.37% and 38.99% respectively. The exergy destructions, exergetic cost allocations, and various exergoeconomic performance parameters are determined by using the exergoeconomic analysis based on specific exergy costing method (SPECO) for the entire plant and its components. The specific unit exergetic cost of the farine, clinker and cement produced by the cement plant are calculated to be 43.77 USD/GJ, 133.72 USD/GJ and 180.5 USD/GJ respectively. The specific manufacturing costs of farine, clinker and cement are found to be 3.8 USD/ton, 33.11 USD/ton and 41.84 USD/ton respectively
[en] In this paper, a large MSF distillation plant in the gulf area is analyzed thermodynamically using actual plant operation data. Exergy flow rates are evaluated throughout the plant, and the exergy flow diagram is prepared. The rates of exergy destruction and their percentages are indicated on the diagram so that the locations of highest exergy destruction can easily be identified. The highest exergy destruction (77.7%) occurs within the MSF unit, as expected, and this can be reduced by increasing the number of flashing stages. The exergy destruction in the pumps and motors account for 5.3% of the total, and this also can be reduced by using high efficiency motors and pumps. The plant is determined to have a second law efficiency of just 4.2%, which is very low. This indicates that there are major opportunities in the plant to reduce exergy destruction and, thus, the amount of electric and thermal energy supplied, making the operation of the plant more cost effective
[en] The use of many common refrigerants is under restriction or phase out because of their high ODP (ozone depletion potential) or GWP (global warming potential). The regulations on environmentally acceptable substances are different from country to country and are subject to frequent updates. In our article, the following mixtures are under consideration: R-401B, R-401C, R-402A, R-404A, R-406A, R-408A, R-409A, R-410A, R-410B and R-507. Some of them do not have zero ODP, but they are in use due to their low ODP. We are focused on performance comparisons of these working fluids in vapor compression refrigerating cycles. Our effort was conducted on the basis of exergy aspects. Various parameters of the cycles were changed within a suitable range, and the results obtained were plotted in graphs of exergy efficiency factors or presented in Grassmann diagrams and tables
[en] Highlights: • Exergoeconomic and exergoenvironmental analyses were applied for a DI diesel engine. • Increasing engine load remarkably decreased the unit cost of shaft work exergy. • Increasing engine speed increased the unit environmental impact of work exergy. • The applied approaches could not detect any spectacular difference among the fuels. - Abstract: In the present study, a DI diesel engine operating on various diesel/biodiesel blends containing different amounts of polymer waste was thermodynamically scrutinized using two exergy-based methods, i.e., exergoeconomic and exergoenvironmental analyses for the first time. Exergoeconomic and exergoenvironmental parameters were calculated for five fuel blends utilized throughout this study at different engine loads and speeds. These approaches were used to make decisions on fuel composition and engine operational conditions by taking into account the financial and environmental issues. The results showed that the exergoeconomic and exergoenvironmental parameters varied profoundly with engine load and speed. In general, increasing engine load remarkably decreased the unit cost and the unit environmental impact of the shaft work exergy, while enhancing engine speed acted oppositely. More specifically, the lowest unit cost and unit environmental impact of full load work exergy were found to be 36.08 USD/MJ and 32.03 mPts/GJ for neat diesel and B5 containing 75 g EPS/L biodiesel, respectively, both at engine speed of 1600 min−1. Moreover, the exergoeconomic and exergoenvironmental factors of the diesel engine were very poor due to the higher thermodynamic losses occurring during the combustion process. Although the maximum exergetic efficiency of the diesel engine was obtained for B5 including 50 g EPS/L biodiesel, the exergoeconomic and exergoenvironmental analyses could not detect any spectacular differences among the fuel blends applied. Overall, using biodiesel in neat or blended form appeared to be less attractive strategy from the exergoeconomic and exergoenvironmental perspectives considering the current biodiesel prices and production technologies.
[en] Highlights: ► A new spectral decomposing approach has been introduced for concentrating PVs. ► Both heating and electrical energy have been gained by CPVCS. ► The full spectrum of solar energy has been utilized by the novel CPVCS. ► The energy and exergy efficiencies were found as 7.3% and 1.16% respectively. ► The energy production cost has been stated as 6.37 $/W. - Abstract: In the present study, a novel Concentrating Photovoltaic Combined System (CPVCS) based on the spectral decomposing approach is introduced, modeled, tested experimentally and evaluated thermodynamically and economically. In this study, energy and exergy analyses of the system have been evaluated, economical analysis has been performed and the experimental results have been compared to data obtained by the control system. As a result, energy efficiencies of concentrator, vacuum tube and overall CPVCS have been determined to be 15.35%; 49.86%; and 7.3% respectively. Similarly the second law (exergy) efficiencies of concentrator, vacuum tube and overall CPVCS are 12.06%; 2.0%; and 1.16% respectively. The cost of energy production has been stated as 6.37 $/W and it is predicted that this value could be decreased by improving the system performance
[en] This paper is concerned with the energy and exergy analyses of the single layer drying process of potato slices via a cyclone type dryer. Using the first law of thermodynamics, an energy analysis was performed to estimate the ratios of energy utilization. An exergy analysis was accomplished to determine the location, type and magnitude of the exergy losses during the drying process by applying the second law of thermodynamics. It was concluded that the exergy losses took place mostly in the 1st tray where the available energy was less utilized during the single layer drying process of potato slices. It is emphasized that the potato slices are sufficiently dried in the ranges between 60 and 80 deg. C and 20-10% relative humidity at 1 and 1.5 ms-1 of drying air velocity during 10-12 h despite the exergy losses of 0-1.796 kJ s-1
[en] A new quantitative structure-property relationship (QSPR) three parameter correlation (R 2 = 0.9977) of standard chemical exergy for a diverse set of 134 organic substances was developed by application of a genetic algorithm search. The descriptors are all calculated directly from the molecular structure, and the approach given is applicable, in principle, to all organic substances of regular structure. The application of the genetic algorithm in comparison with stepwise multi-variate linear regression (MLR) shows some advantages in required time for solving and in precision
[en] Highlights: • A generalized diagnosis approach dealing with simultaneous multiple malfunctions. • An internal exergy factor for fast and effective identification of malfunction sources. • The endogenous exergy destruction calculated for accurate malfunction quantification. - Abstract: During continuous operation of energy systems, the performance of components will mostly, gradually deviate away from the reference conditions due to performance degradation, which may eventually lead to malfunctions or operation failure. The complex interconnection among components and the propagation nature of additional irreversibility caused by malfunctions increase the difficulty of malfunction diagnosis. Particularly, in common real-world cases, multiple malfunctions usually happen simultaneously in several different components, imposing additional difficulty for effective malfunction identification and quantification. In this paper, we generalize an effective diagnosis method recently proposed by the authors to accurately locate the malfunction component and quantify the effect caused by anomalies of multiple malfunctions. The generalized method is based on advanced exergy analysis, where exergy destruction within each component is split into endogenous and exogenous parts. The endogenous exergy destruction is due to the irreversibility of the component itself, while the exogenous is caused by the inefficiencies of the remaining components. The exogenous exergy destruction is, in fact, the major obstacle to accurately pinpoint the origins of performance degradation. In the generalized approach, an internal exergy indicator is recommended to be applied first to identify the malfunction components in a fast and effective manner. Then the endogenous exergy destruction of the identified malfunction components under the reference and degradation conditions is calculated and compared for accurate quantification. The generalized diagnosis approach is applied to a complex real-world case studies, in which several malfunctions are introduced simultaneously into different components. The results show that the proposed indicator could fast identify the source of anomalies while the endogenous exergy destruction successfully and effectively quantifies all introduced malfunctions.
[en] Highlights: ► We analyze the energy and exergy utilizations of the Jordanian SMEs industries. ► We developed an energy balance for the Jordanian SMEs industries. ► The low efficiencies values suggest that many opportunities for better industrial energy utilizations still exist. - Abstract: This study presents detailed analysis of the energy and exergy utilizations of the Jordanian Small-Medium Enterprises (SMEs) by considering the flows of energy and exergy through the main end uses in the Jordanian industrial sector. To achieve this purpose, a survey covering 180 facilities was conducted and energy consumption data was gathered to establish detailed end-use balance for the Jordanian industrial sector. The energy end-use balance provides a starting point to estimate the site and embodied energy and exergy efficiencies. The average site energy and exergy efficiencies of the Jordanian SMEs industries sector are estimated as 78.3% and 37.9% respectively, while the embodied energy and exergy efficiencies are estimated as 58.9% and 21.2% respectively. The low efficiencies values suggest that many opportunities for better industrial energy utilizations still exist.
[en] The cumulative consumption of non-renewable exergy connected with the fabrication of particular products has been termed as their ecological cost. System of linear input-output equations determining the ecological costs have been formulated. The cogeneration processes have been considered using the principle of the avoided costs of fabrication of the products substituted by the by-products of the considered process. The ecological cost determined in a regional scope takes into account the ecological cost of the imported raw materials and semi-finished products. These quantities have been substituted by the economically equivalent export of own products. The deleterious effect of the rejection of waste products to the environment has been approximately determined by means of the monetary indices of harmfulness of waste products. It has been proved, that the ecological cost of human work cannot be introduced into the set of input-output equations. Exemplary calculations have been made for the products connected with the blast-furnace process. The influence of the injection of auxiliary fuels into the blast furnace on the ecological cost of pig iron has been analyzed too. (Author)