The Experts below are selected from a list of 1044 Experts worldwide ranked by ideXlab platform
Zhaozhi Zhou - One of the best experts on this subject based on the ideXlab platform.
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Energy and Exergy Analyses of Fluidized-Bed Municipal Solid Waste Air Gasification
Energy and Fuels, 2016Co-Authors: Yuanjun Tang, Jun Dong, Yong Chi, Zhaozhi ZhouAbstract:With the aim of optimizing gasification systems, air gasification using simulated municipal solid waste is experimentally investigated in a fluidized-bed reactor. Process parameters considered include equivalence ratio (ER) and temperature. On the basis of the experimental results, energy and Exergy analyses are performed to assess the thermodynamic quality. Results reveal that the energy and Exergy Contents of the produced gas increase first with rising temperature and then decline when the temperature exceeds 650 degrees C. With regard to the ER, a similar tendency is observed with a peak value at an ER of 0.4. The energy Content of the produced gas is much higher than its Exergy Content as a result of the remarkable difference between physical energy and Exergy Contents of sensible heat. The maximum chemical energy efficiency, total energy efficiency, chemical Exergy efficiency, and total Exergy efficiency of the, products at the gasifier exit are attained at an ER of 0.4 and a temperature of 650 degrees C, with values of 49.73, 64.05, 47.14, and 51.33%, respectively. The total Exergy efficiency is suggested as an effective parameter to evaluate the properties of gasification-based thermal systems, because it expresses the availability of the products from the ``first-step'' gasifier for subsequent conversion.
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Energy and Exergy Analyses of Fluidized-Bed Municipal Solid Waste Air Gasification
Energy & Fuels, 2016Co-Authors: Yuanjun Tang, Jun Dong, Yong Chi, Zhaozhi ZhouAbstract:With the aim of optimizing gasification systems, air gasification using simulated municipal solid waste is experimentally investigated in a fluidized-bed reactor. Process parameters considered include equivalence ratio (ER) and temperature. On the basis of the experimental results, energy and Exergy analyses are performed to assess the thermodynamic quality. Results reveal that the energy and Exergy Contents of the produced gas increase first with rising temperature and then decline when the temperature exceeds 650 °C. With regard to the ER, a similar tendency is observed with a peak value at an ER of 0.4. The energy Content of the produced gas is much higher than its Exergy Content as a result of the remarkable difference between physical energy and Exergy Contents of sensible heat. The maximum chemical energy efficiency, total energy efficiency, chemical Exergy efficiency, and total Exergy efficiency of the products at the gasifier exit are attained at an ER of 0.4 and a temperature of 650 °C, with valu...
Ibrahim Dincer - One of the best experts on this subject based on the ideXlab platform.
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Performance assessment of a magnesium chloride saturated solar pond
Renewable Energy, 2015Co-Authors: Ismail Bozkurt, Sibel Deniz, Mehmet Karakilcik, Ibrahim DincerAbstract:This paper deals with the experimental investigation of a magnesium chloride saturated solar pond and its performance evaluation through energy and Exergy efficiencies. The solar pond system is filled with magnesium chloride containing water to form layers with varying densities. A solar pond generally consists of three zones, and the densities of these zones increase from the top convective zone to the bottom storage zone. The incoming solar radiation is absorbed by salty water (with magnesium chloride) which eventually increases the temperature of the storage zone. The high-temperature salty water at the bottom of the solar pond remains much denser than the salty water in the upper layers. Thus, the convective heat losses are prevented by gradient layers. The experimental temperature changes of the solar pond are measured by using thermocouples from August to November. The densities of the layers are also measured and analysed by taking samples from at the same point of the temperature sensors. The energy and Exergy Content distributions are determined for the heat storage zone and the non-convective zone. The maximum Exergy destructions and losses appear to be 79.05 MJ for the heat storage zone and 175.01 MJ for the non-convective zone in August. The energy and Exergy efficiencies of the solar pond are defined as a function of solar radiation and temperatures. As a result, the maximum energy and Exergy efficiencies are found to be 27.41% and 26.04% for the heat storage zone, 19.71% and 17.45% for the non-convective zone in August, respectively.
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Assessment of Maisotsenko Combustion Turbine Cycle with Compressor Inlet Cooler
Progress in Clean Energy Volume 1, 2015Co-Authors: Hakan Caliskan, Ibrahim Dincer, Arif HepbasliAbstract:In this study, a Maisotsenko combustion turbine cycle (MCTC) with compressor inlet cooling system is proposed and studied through energy, Exergy and exergoeconomic analysis methods. The present system consists of a Maisotsenko air cooler, a compressor, a turbine, a generator, a combustor, and a compressed air saturator. The results show that an Exergy efficiency of 58.27 % is higher than the corresponding energy efficiency of 51.55 % for the MCTC system, due to the fact that the Exergy Content of the fuel fed into the combustion chamber is lower than its energy Content. Also, the maximum Exergy destruction rates occur in the compressor and turbine with the values of 166.964 kW and 150.864 kW, respectively. Furthermore, the exergoeconomic results indicate that the highest exergetic cost factor defined as the destruction in the component per cost is determined to be 0.013148 kW/$ for the turbine, while the Maisotsenko cycle air cooler has a minimum rate of 0.000006 kW/$. The better optimization of this component may be considered. It is concluded that Maisotsenko cycle systems can be effectively integrated to turbine cycle systems. Also, energy, Exergy and exergoeconomic analyses give more useful information together about assessing the MCTC system and minimizing the thermodynamic inefficiencies.
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Exergy analysis of a high pressure multistage hydrogen gas storage system
International Journal of Hydrogen Energy, 2011Co-Authors: Mert Ozsaban, Adnan Midilli, Ibrahim DincerAbstract:Abstract This study presents a parametric study on the performance aspects, through Exergy analysis, of the multistage hydrogen gas storage subsystem in a hydropower-based-hydrogen gas fueling station producing 3 kg of hydrogen per hour and storing it. In order to perform an Exergy analysis, the following parameters are taken into consideration: (i) mass flow rate of hydrogen (3 kg/h), (ii) inlet pressure of hydrogen (ranging from 1 to 200 bar), (iii) hydrogen storage pressure (ranging from 200 to 900 bar), (iv) dead state temperature (at 25 °C), (v) efficiency of electrical motor (90%), (vi) mechanical efficiency (95%), and (vii) polytropic efficiency (90%). It is obtained that increasing inlet pressure of hydrogen gas decreases the energy consumption for compression and storage process while increasing Exergy efficiency. Moreover, it is noticed that increasing storage pressure increases the Exergy Content of hydrogen gas.
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Effect of stratification on energy and Exergy capacities in thermal storage systems
International Journal of Energy Research, 2004Co-Authors: Marc A. Rosen, Raymond Tang, Ibrahim DincerAbstract:The increase in Exergy storage capacity that is attained in thermal storages through stratification is assessed. A design-oriented temperature-distribution model for vertically stratified thermal storages that facilitates the evaluation of storage energy and Exergy Contents is utilized. The paper is directed towards demonstrating the thermodynamic benefits achieved through stratification, and increasing the utilization of Exergy-based performance measures for stratified thermal storages. A wide range of realistic storage-fluid temperature profiles is considered, and for each the relative increase in Exergy Content of the stratified storage compared to the same storage when it is fully mixed is evaluated. The results indicate that, for all temperature profiles considered, the Exergy storage capacity of a thermal storage increases when it is stratified, and increases as the degree of stratification, as represented through greater and sharper spatial temperature variations, increases. Furthermore, the percentage increase in Exergy capacity is greatest for storages at temperatures near to the environment temperature, and decreases as the mean storage temperature diverges from the environment temperature (to either higher or lower temperatures). It is concluded that (i) the use of stratification in thermal storage designs should be considered as it increases the Exergy storage capacity of a thermal storage and (ii) Exergy analysis should be applied in the analysis and comparison of stratified thermal storage systems.
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Is bigger thermodynamically better
Exergy An International Journal, 2002Co-Authors: Yunus A. Cengel, Byard D. Wood, Ibrahim DincerAbstract:Abstract Mixing, in general, is an irreversible process, and some entropy is generated and thus some Exergy is destroyed during such a process. Therefore, combining two systems thermodynamically that are at different states may yield a system that is larger in size, but much smaller in Exergy Content or “usefulness”. In this paper we consider some mixing processes, and show that getting bigger is not necessarily better by examining the effect of mixing on Exergy destruction.
M A Reuter - One of the best experts on this subject based on the ideXlab platform.
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quantifying the quality loss and resource efficiency of recycling by means of Exergy analysis
Journal of Cleaner Production, 2007Co-Authors: S H Amini, Maria B G Castro, J A M Remmerswaal, M A ReuterAbstract:Abstract Contaminants cause a decrease in the quality of materials with each recycling step. These quality losses should be minimized to increase the sustainability of resources use. Quality losses cannot be measured using weight-based recovery definitions alone, as the quality degradation cannot be translated by mass measures. Therefore, a better measure of the efficiency of resource use is investigated in the present work. Exergy is a measure of the quality of the energy and of resources in systems. The Exergy losses are a thermodynamic measure of exhaustion and thus, of the quality losses in the resource systems. We describe a method to calculate the Exergy Content and Exergy losses of metals during recovery and recycling of a concept car. The Exergy losses attributed to recycling (the pollution with other metals) and the consequent need for dilution can be used as indicators of the quality loss of materials and of the efficiency of resource use in product systems.
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Exergy losses during recycling and the resource efficiency of product systems
Resources Conservation and Recycling, 2007Co-Authors: Maria B G Castro, J A M Remmerswaal, J.c. Brezet, M A ReuterAbstract:Recycling materials have always some degree of contamination. The presence of contaminations in the recycling streams causes a shift in the original composition of the materials to recycle. As a consequence, their quality may decrease with each recycling step. Additionally, lower quality resources are produced from resource streams that had initially a higher quality. These quality losses cannot be measured by mass balances, as the quality degradation cannot be translated by mass measures alone. To account all losses caused by recycling contaminations, all downstream recycling processes required to bring the materials back to the resource cycles must be included. This article describes a method to calculate the Exergy Content and Exergy losses of metal solutions during recovery and recycling. The losses attributed to recycling, namely the material losses, the contamination losses with other metals, and the consequent need for dilution can be used as indicators of the quality loss of materials and of the efficiency of resource use in product systems. Therefore, Exergy is proposed here as a measure of the efficiency of resources use.
Yuanjun Tang - One of the best experts on this subject based on the ideXlab platform.
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Energy and Exergy Analyses of Fluidized-Bed Municipal Solid Waste Air Gasification
Energy and Fuels, 2016Co-Authors: Yuanjun Tang, Jun Dong, Yong Chi, Zhaozhi ZhouAbstract:With the aim of optimizing gasification systems, air gasification using simulated municipal solid waste is experimentally investigated in a fluidized-bed reactor. Process parameters considered include equivalence ratio (ER) and temperature. On the basis of the experimental results, energy and Exergy analyses are performed to assess the thermodynamic quality. Results reveal that the energy and Exergy Contents of the produced gas increase first with rising temperature and then decline when the temperature exceeds 650 degrees C. With regard to the ER, a similar tendency is observed with a peak value at an ER of 0.4. The energy Content of the produced gas is much higher than its Exergy Content as a result of the remarkable difference between physical energy and Exergy Contents of sensible heat. The maximum chemical energy efficiency, total energy efficiency, chemical Exergy efficiency, and total Exergy efficiency of the, products at the gasifier exit are attained at an ER of 0.4 and a temperature of 650 degrees C, with values of 49.73, 64.05, 47.14, and 51.33%, respectively. The total Exergy efficiency is suggested as an effective parameter to evaluate the properties of gasification-based thermal systems, because it expresses the availability of the products from the ``first-step'' gasifier for subsequent conversion.
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Energy and Exergy Analyses of Fluidized-Bed Municipal Solid Waste Air Gasification
Energy & Fuels, 2016Co-Authors: Yuanjun Tang, Jun Dong, Yong Chi, Zhaozhi ZhouAbstract:With the aim of optimizing gasification systems, air gasification using simulated municipal solid waste is experimentally investigated in a fluidized-bed reactor. Process parameters considered include equivalence ratio (ER) and temperature. On the basis of the experimental results, energy and Exergy analyses are performed to assess the thermodynamic quality. Results reveal that the energy and Exergy Contents of the produced gas increase first with rising temperature and then decline when the temperature exceeds 650 °C. With regard to the ER, a similar tendency is observed with a peak value at an ER of 0.4. The energy Content of the produced gas is much higher than its Exergy Content as a result of the remarkable difference between physical energy and Exergy Contents of sensible heat. The maximum chemical energy efficiency, total energy efficiency, chemical Exergy efficiency, and total Exergy efficiency of the products at the gasifier exit are attained at an ER of 0.4 and a temperature of 650 °C, with valu...
J. Paris - One of the best experts on this subject based on the ideXlab platform.
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base case process development for energy efficiency improvement application to a kraft pulping mill part ii benchmarking analysis
Chemical Engineering Research & Design, 2011Co-Authors: Enrique Mateosespejel, Luciana Savulescu, Francois Marechal, J. ParisAbstract:A new procedure for benchmarking analysis has been developed to evaluate the energy efficiency of a chemical process. Benchmarking is performed to identify process inefficiencies before developing energy enhancement measures. The new procedure combines typical techniques, such as the comparison with current practice, with utilization of new performance indicators based on Exergy and energy Content and the targeting by Pinch Analysis and Water Pinch. All process sections and the steam and water utility systems are evaluated. The procedure consists of five phases. In the first phase the data required is compiled. The second phase consists of comparing the energy and water efficiency of the base case to the current practice of the industry. In the third phase, the new energy and Exergy Content indicators are used to analyze the efficiency of utilities systems and to quantify the heat rejected by the process. In the fourth phase the minimum energy and water requirements are determined. The last phase is a synthesis by which the inefficiencies are identified and guidelines established for process improvement. Interactions between the utilities systems and the process are developed. The procedure has been applied to an operating Kraft pulping mill in Eastern Canada. (C) 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
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unified methodology for thermal energy efficiency improvement application to kraft process
Chemical Engineering Science, 2011Co-Authors: Enrique Mateosespejel, Luciana Savulescu, Francois Marechal, J. ParisAbstract:A unified methodology that can be used to identify the interactions between the utilities systems and the process, as well as their impacts on the implementation of energy efficiency measures is presented. It takes into account steam and water systems to analyze the process and formulate energy enhancement measures. It has been applied to an operating Kraft mill in Eastern Canada. The methodology consists of five stages: base-case process definition and characterization, pre-benchmarking, systems interactions analysis, implementation strategy and post-benchmarking. A simulation focused on the energy and water systems is first developed and used as basis of the analysis. The pre-benchmarking characterizes the current energy efficiency of the process by three techniques: energy and Exergy Content indicators, comparison to the current industrial practice and establishing targets for minimum energy and water requirements determined by the Thermal Pinch and Water Pinch methods. The systems interactions are analyzed to develop complementary energy efficiency measures by applying several energy enhancing techniques. A three-phase strategy is proposed to implement the identified measures. The application of the unified methodology results in an eco-friendly process that does not require fossil fuel for steam production and generates revenues by producing green electricity from biomass. In the case study presented, very significant energy gains have been proposed (26.6% steam requirement reduction and 33.6% fresh water intake reduction).
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Unified methodology for thermal energy efficiency improvement: Application to Kraft process
Chemical Engineering Science, 2011Co-Authors: Enrique Mateos-espejel, Luciana Savulescu, Francois Marechal, J. ParisAbstract:A unified methodology that can be used to identify the interactions between the utilities systems and the process, as well as their impacts on the implementation of energy efficiency measures is presented. It takes into account steam and water systems to analyze the process and formulate energy enhancement measures. It has been applied to an operating Kraft mill in Eastern Canada. The methodology consists of five stages: base-case process definition and characterization, pre-benchmarking, systems interactions analysis, implementation strategy and post-benchmarking. A simulation focused on the energy and water systems is first developed and used as basis of the analysis. The pre-benchmarking characterizes the current energy efficiency of the process by three techniques: energy and Exergy Content indicators, comparison to the current industrial practice and establishing targets for minimum energy and water requirements determined by the Thermal Pinch and Water Pinch methods. The systems interactions are analyzed to develop complementary energy efficiency measures by applying several energy enhancing techniques. A three-phase strategy is proposed to implement the identified measures. The application of the unified methodology results in an eco-friendly process that does not require fossil fuel for steam production and generates revenues by producing green electricity from biomass. In the case study presented, very significant energy gains have been proposed (26.6% steam requirement reduction and 33.6% fresh water intake reduction).