The Experts below are selected from a list of 2610 Experts worldwide ranked by ideXlab platform

S C Kaushik - One of the best experts on this subject based on the ideXlab platform.

  • exergetic utilization of solar energy for feed water preheating in a conventional thermal power plant
    International Journal of Energy Research, 2009
    Co-Authors: M K Gupta, S C Kaushik
    Abstract:

    This communication is based on Exergy Concept for the utilization of solar thermal energy in a Rankine cycle-based fuel-fired thermal power plant (FFTPP). It has been shown that solar thermal energy as an aided source for feed water preheating helps to reduce the Exergy loss in feed water heater (FWH) of Rankine cycle and develops more work than that could have been produced in a solar thermal power plant (STPP). It has been found that this enhancement in work increases for low-pressure FWHs. For further illustration, a case study has been carried out of a typical 50 kW STPP and a 220 MW FFTPP. The effect of utilizing the same input solar thermal energy of typical STPP, if used as an aided source in a 220 MW FFTPP for feed water preheating is investigated. The work output of STPP is 59.312 kW, while the extra work output of FFTPP by using solar thermal energy of STPP is 90.27 kW. It has been found that the efficiency of work conversion of aided solar thermal energy in FFTPP is higher than the efficiency of work conversion in STPP. Copyright © 2009 John Wiley & Sons, Ltd.

  • exergetic analysis of a solar thermal power system
    Renewable Energy, 2000
    Co-Authors: Narendra Singh, S C Kaushik, Rahul Dev Misra
    Abstract:

    Abstract This communication presents a second law analysis based on an Exergy Concept for a solar thermal power system. Basic energy and Exergy analysis for the system components (viz. parabolic trough collector/receiver and Rankine heat engine, etc.) are carried out for evaluating the respective losses as well as exergetic efficiency for typical solar thermal power systems under given operating conditions. It is found that the main energy loss takes place at the condenser of the heat engine part, whereas the Exergy analysis shows that the collector–receiver assembly is the part where the losses are maximum. The analysis and results can be used for evaluating the component irreversibilities which can also explain the deviation between the actual efficiency and ideal efficiency of a solar thermal power system.

  • SECOND LAW ANALYSIS OF A SOLAR THERMAL POWER SYSTEM
    International Journal of Solar Energy, 2000
    Co-Authors: S C Kaushik, Rahul Dev Misra, Narendra Singh
    Abstract:

    This communication presents second law analysis based on Exergy Concept for a solar thermal power system. Basic energy and Exergy analysis for the system components (viz. parabolic trough collector/receiver and Rankine heat engine etc.) are carried out for evaluating the energy and Exergy losses as well as exergetic efficiency for typical solar thermal power system under given operating conditions. Relevant energy flow and Exergy flow diagrams are drawn to show the various thermodynamic and thermal losses. It is found that the main energy loss takes place at the condenser of the heat engine part whereas the Exergy analysis shows that the collector-receiver assembly is the part where the losses are maximum. The analysis and results can be used for evaluating the component irreversibilities which can also explain the deviation between the actual efficiency and ideal efficiency of solar thermal power system.

  • Second Law analysis of a Rankine heat engine with reheat and regenerative options for solar thermal power generation
    International Journal of Ambient Energy, 2000
    Co-Authors: S C Kaushik, Rahul Dev Misra, Narendra Singh
    Abstract:

    SYNOPSIS This communication presents the Second Law analysis based on the Exergy Concept for the performance of Simple and Regenerative-Reheat Rankine heat engines generally used in Solar Thermal Power Systems. Basic energy and Exergy analysis for the heat engine system components are carried out for evaluating the energy and Exergy losses as well as the exergetic efficiencies for both the Simple and Regenerative-Reheat Rankine heat engines. Relevant energy and Exergy flow diagrams are drawn to show the various thermodynamic and thermal losses. It is found from the results that most of the Exergy losses occur in the boiler and these losses are significantly reduced by the incorporation of a regenerator and reheater, whereas the results of the energy analysis shows that the main energy loss takes place in the condenser. This is because in the boiler high quality energy is lost but in the condenser low quality energy is lost. The incorporation of the regenerator and reheater results in a reduction of the total irreversibility rate of the cycle by 28.77%. The corresponding improvement in the exergetic efficiency is 16.42%.

Rahul Dev Misra - One of the best experts on this subject based on the ideXlab platform.

  • exergetic analysis of a solar thermal power system
    Renewable Energy, 2000
    Co-Authors: Narendra Singh, S C Kaushik, Rahul Dev Misra
    Abstract:

    Abstract This communication presents a second law analysis based on an Exergy Concept for a solar thermal power system. Basic energy and Exergy analysis for the system components (viz. parabolic trough collector/receiver and Rankine heat engine, etc.) are carried out for evaluating the respective losses as well as exergetic efficiency for typical solar thermal power systems under given operating conditions. It is found that the main energy loss takes place at the condenser of the heat engine part, whereas the Exergy analysis shows that the collector–receiver assembly is the part where the losses are maximum. The analysis and results can be used for evaluating the component irreversibilities which can also explain the deviation between the actual efficiency and ideal efficiency of a solar thermal power system.

  • SECOND LAW ANALYSIS OF A SOLAR THERMAL POWER SYSTEM
    International Journal of Solar Energy, 2000
    Co-Authors: S C Kaushik, Rahul Dev Misra, Narendra Singh
    Abstract:

    This communication presents second law analysis based on Exergy Concept for a solar thermal power system. Basic energy and Exergy analysis for the system components (viz. parabolic trough collector/receiver and Rankine heat engine etc.) are carried out for evaluating the energy and Exergy losses as well as exergetic efficiency for typical solar thermal power system under given operating conditions. Relevant energy flow and Exergy flow diagrams are drawn to show the various thermodynamic and thermal losses. It is found that the main energy loss takes place at the condenser of the heat engine part whereas the Exergy analysis shows that the collector-receiver assembly is the part where the losses are maximum. The analysis and results can be used for evaluating the component irreversibilities which can also explain the deviation between the actual efficiency and ideal efficiency of solar thermal power system.

  • Second Law analysis of a Rankine heat engine with reheat and regenerative options for solar thermal power generation
    International Journal of Ambient Energy, 2000
    Co-Authors: S C Kaushik, Rahul Dev Misra, Narendra Singh
    Abstract:

    SYNOPSIS This communication presents the Second Law analysis based on the Exergy Concept for the performance of Simple and Regenerative-Reheat Rankine heat engines generally used in Solar Thermal Power Systems. Basic energy and Exergy analysis for the heat engine system components are carried out for evaluating the energy and Exergy losses as well as the exergetic efficiencies for both the Simple and Regenerative-Reheat Rankine heat engines. Relevant energy and Exergy flow diagrams are drawn to show the various thermodynamic and thermal losses. It is found from the results that most of the Exergy losses occur in the boiler and these losses are significantly reduced by the incorporation of a regenerator and reheater, whereas the results of the energy analysis shows that the main energy loss takes place in the condenser. This is because in the boiler high quality energy is lost but in the condenser low quality energy is lost. The incorporation of the regenerator and reheater results in a reduction of the total irreversibility rate of the cycle by 28.77%. The corresponding improvement in the exergetic efficiency is 16.42%.

Narendra Singh - One of the best experts on this subject based on the ideXlab platform.

  • exergetic analysis of a solar thermal power system
    Renewable Energy, 2000
    Co-Authors: Narendra Singh, S C Kaushik, Rahul Dev Misra
    Abstract:

    Abstract This communication presents a second law analysis based on an Exergy Concept for a solar thermal power system. Basic energy and Exergy analysis for the system components (viz. parabolic trough collector/receiver and Rankine heat engine, etc.) are carried out for evaluating the respective losses as well as exergetic efficiency for typical solar thermal power systems under given operating conditions. It is found that the main energy loss takes place at the condenser of the heat engine part, whereas the Exergy analysis shows that the collector–receiver assembly is the part where the losses are maximum. The analysis and results can be used for evaluating the component irreversibilities which can also explain the deviation between the actual efficiency and ideal efficiency of a solar thermal power system.

  • SECOND LAW ANALYSIS OF A SOLAR THERMAL POWER SYSTEM
    International Journal of Solar Energy, 2000
    Co-Authors: S C Kaushik, Rahul Dev Misra, Narendra Singh
    Abstract:

    This communication presents second law analysis based on Exergy Concept for a solar thermal power system. Basic energy and Exergy analysis for the system components (viz. parabolic trough collector/receiver and Rankine heat engine etc.) are carried out for evaluating the energy and Exergy losses as well as exergetic efficiency for typical solar thermal power system under given operating conditions. Relevant energy flow and Exergy flow diagrams are drawn to show the various thermodynamic and thermal losses. It is found that the main energy loss takes place at the condenser of the heat engine part whereas the Exergy analysis shows that the collector-receiver assembly is the part where the losses are maximum. The analysis and results can be used for evaluating the component irreversibilities which can also explain the deviation between the actual efficiency and ideal efficiency of solar thermal power system.

  • Second Law analysis of a Rankine heat engine with reheat and regenerative options for solar thermal power generation
    International Journal of Ambient Energy, 2000
    Co-Authors: S C Kaushik, Rahul Dev Misra, Narendra Singh
    Abstract:

    SYNOPSIS This communication presents the Second Law analysis based on the Exergy Concept for the performance of Simple and Regenerative-Reheat Rankine heat engines generally used in Solar Thermal Power Systems. Basic energy and Exergy analysis for the heat engine system components are carried out for evaluating the energy and Exergy losses as well as the exergetic efficiencies for both the Simple and Regenerative-Reheat Rankine heat engines. Relevant energy and Exergy flow diagrams are drawn to show the various thermodynamic and thermal losses. It is found from the results that most of the Exergy losses occur in the boiler and these losses are significantly reduced by the incorporation of a regenerator and reheater, whereas the results of the energy analysis shows that the main energy loss takes place in the condenser. This is because in the boiler high quality energy is lost but in the condenser low quality energy is lost. The incorporation of the regenerator and reheater results in a reduction of the total irreversibility rate of the cycle by 28.77%. The corresponding improvement in the exergetic efficiency is 16.42%.

Mortaza Aghbashlo - One of the best experts on this subject based on the ideXlab platform.

  • The critical role of advanced sustainability assessment tools in enhancing the real-world application of biofuels
    Acta Innovations, 2020
    Co-Authors: Meisam Tabatabaei, Mortaza Aghbashlo
    Abstract:

    Sustainability has become of paramount importance in the biofuel industry. Accordingly, various ‎sustainability assessment schemes such as emergy analysis, techno-economic analysis, life ‎cycle ‎assessment, energy accounting, and Exergy analysis and its extensions (exergoeconomic, ‎exergoenvironmental, and ‎exergoeconoenvironmental analyses) are being employed increasingly for decision-‎making on biofuel production and consumption systems. In this opinion paper, after classifying ‎and describing biofuel generations, the developed sustainability assessment tools are critically ‎explained, and their pros and cons are discussed. Overall, among the various sustainability assessment approaches introduced so far, Exergy-based methods appear to be ‎the most promising tools for developing ‎sustainable biofuel systems. This can be attributed to the fact that the Exergy ‎Concept is deeply ‎rooted in the well-defined principles of thermodynamics.‎

  • Comprehensive Exergy analysis of a commercial tomato paste plant with a double-effect evaporator
    Energy, 2016
    Co-Authors: Mohamad Mojarab Soufiyan, Ali Dadak, Seyed Sina Hosseini, Farshid Nasiri, Majid Dowlati, Maryam Tahmasebi, Mortaza Aghbashlo
    Abstract:

    In this study, a detailed Exergy evaluation of a commercial tomato paste plant with a double-effect evaporator was conducted in order to provide information on the system thermodynamic inefficiencies. Using energy and Exergy balance equations, all components of the plant were analyzed individually and their exergetic parameters were calculated on the basis of actual operational data. The required data were obtained from Nazchin tomato paste factory located in Tehran, Iran. In addition, it was attempted to quantify the Exergy utilized for processing a given amount of the tomato paste. The results showed that over 82% of the total destroyed Exergy in the plant occurred in the boiler combination as the main component wasting Exergy. Furthermore, Exergy analysis introduced this combination as the main equipment rejecting Exergy to the ambient where 4.79% of its total Exergy input was lost. The rational Exergy efficiency of the first- and second-effect evaporative units was found to be 65.33% and 56.60%, respectively. The specific Exergy consumption of the tomato paste production was also determined as 16.83 MJ/kg. Generally, Exergy Concept and its extensions could be served as a powerful assessment technique to optimize the design and performance of multiple-effect evaporation systems employed in food industry.

  • Performance analysis of a continuous bioreactor for ethanol and acetate synthesis from syngas via Clostridium ljungdahlii using Exergy Concept
    Clean Technologies and Environmental Policy, 2016
    Co-Authors: Mortaza Aghbashlo, Seyed Sina Hosseini, Meisam Tabatabaei, Habibollah Younesi, Ghasem D. Najafpour
    Abstract:

    In this paper, the exergetic performance of a continuous bioreactor for ethanol and acetate synthesis from syngas via a strictly anaerobic autotrophic bacterium Clostridium ljungdahlii was carried out for the first time. The fermentation process was evaluated using both conventional Exergy and eco-Exergy principles for measuring the productivity and renewability of the process at various liquid media flow rates. The microorganisms successfully upgraded the syngas into invaluable ethanol and acetate through the Wood–Ljungdahl pathway. The Exergy efficiency was found to be in the range of 6.5–77.5 and 6.8–77.5 % during the fermentation using conventional Exergy and eco-Exergy Concepts, respectively. The subtle differences observed in the exergetic parameters using the two exergetic Concepts were ascribed to the slow growth rate of the microorganisms. Nevertheless, the eco-Exergy Concept would strongly be recommended for commercial bioreactor containing living organisms due to the inclusion of the information carried by microorganisms in the exergetic calculation. A desired liquid media flow rate of 0.55 mL/min was found according to a newly defined thermodynamic indictor namely exergetic productivity index. More specifically, the maximum exergetic productivity index of the fermentation process was found to be 8.0 using both approaches when the rate of inflow liquid was adjusted at the optimal value. The results of this study revealed that process yield alone cannot be a reliable performance metric for decision making on the productivity of various biofuel production pathways. Finally, the proposed exergetic framework could assist engineers and researchers to link biochemical and physical knowledge more robustly and to quantify and elucidate the general purpose of productivity and renewability.

  • Exergy analysis for decision making on operational condition of a continuous photobioreactor for hydrogen production via wgs reaction
    International Journal of Hydrogen Energy, 2016
    Co-Authors: Mortaza Aghbashlo, Seyed Sina Hosseini, Meisam Tabatabaei, Habibollah Younesi, Ghasem D. Najafpour
    Abstract:

    Abstract In the present study, continuous photobiological hydrogen production from syngas through the water gas shift (WGS) reaction by Rhodospirillum rubrum was thermodynamically scrutinized using both conventional Exergy and eco-Exergy Concepts for the first time. These analyses were applied for decision making on liquid media flow rate and agitation speed with respect to the sustainability and productivity issues. The maximum process exergetic efficiency was found to be 22.27% and 22.09% using the conventional Exergy and eco-Exergy Concepts, respectively, at a liquid media flow rate of 12 mL/min and an agitation speed of 500 rpm as the best operational conditions. In general, the eco-exergetic parameters and their conventional Exergy counterparts did not show significant differences due to the slow growth rate of the microorganisms in the bioreactor. However, eco-Exergy Concept would be strongly recommended to apply for analyzing such renewable fuel production systems containing living organisms. Moreover, this work demonstrated the merits of exergetic indicators based on the second law of thermodynamics over the single process yield in assessing photobiological hydrogen production. The results obtained also showed that Exergy analysis could facilitate on-going attempts to increase the sustainability and productivity of large-scale photobiological hydrogen production systems.

  • Exergy analysis of biohydrogen production from various carbon sources via anaerobic photosynthetic bacteria rhodospirillum rubrum
    Energy, 2015
    Co-Authors: Seyed Sina Hosseini, Mortaza Aghbashlo, Meisam Tabatabaei, Habibollah Younesi, Ghasem D. Najafpour
    Abstract:

    In this study, Exergy analysis of batch biohydrogen production through WGS (water–gas shift) reaction using an anaerobic photosynthetic bacteria Rhodospirillum rubrum was carried out for the first time. Various carbon sources including formate, acetate, malate, glucose, fructose, and sucrose were applied to support microbial growth in the presence of CO-rich syngas. The microorganisms utilized carbon monoxide and produced molecular hydrogen concurrently. The process was analyzed based on both conventional Exergy and eco-Exergy Concepts for determining the exergetic parameters i.e., Exergy destruction and Exergy efficiency. Unlike the Exergy efficiency, the Exergy destruction based on the eco-Exergy Concept was remarkably lower than what obtained via the conventional Exergy theory. Minimum normalized Exergy destruction values of 189.67 and 181.40 kJ/kJ H2 were achieved for acetate as substrate using the Exergy and eco-Exergy approaches, respectively. In better words, acetate was identified as the most appropriate carbon source for biohydrogen production from the Exergy point of view. Finally, the findings of this study confirmed that Exergy analysis could be employed as an adaptable framework to determine and compare the renewability of biological hydrogen production using different routes in order to decide on the most suitable approach and conditions.

Ghasem D. Najafpour - One of the best experts on this subject based on the ideXlab platform.

  • Performance analysis of a continuous bioreactor for ethanol and acetate synthesis from syngas via Clostridium ljungdahlii using Exergy Concept
    Clean Technologies and Environmental Policy, 2016
    Co-Authors: Mortaza Aghbashlo, Seyed Sina Hosseini, Meisam Tabatabaei, Habibollah Younesi, Ghasem D. Najafpour
    Abstract:

    In this paper, the exergetic performance of a continuous bioreactor for ethanol and acetate synthesis from syngas via a strictly anaerobic autotrophic bacterium Clostridium ljungdahlii was carried out for the first time. The fermentation process was evaluated using both conventional Exergy and eco-Exergy principles for measuring the productivity and renewability of the process at various liquid media flow rates. The microorganisms successfully upgraded the syngas into invaluable ethanol and acetate through the Wood–Ljungdahl pathway. The Exergy efficiency was found to be in the range of 6.5–77.5 and 6.8–77.5 % during the fermentation using conventional Exergy and eco-Exergy Concepts, respectively. The subtle differences observed in the exergetic parameters using the two exergetic Concepts were ascribed to the slow growth rate of the microorganisms. Nevertheless, the eco-Exergy Concept would strongly be recommended for commercial bioreactor containing living organisms due to the inclusion of the information carried by microorganisms in the exergetic calculation. A desired liquid media flow rate of 0.55 mL/min was found according to a newly defined thermodynamic indictor namely exergetic productivity index. More specifically, the maximum exergetic productivity index of the fermentation process was found to be 8.0 using both approaches when the rate of inflow liquid was adjusted at the optimal value. The results of this study revealed that process yield alone cannot be a reliable performance metric for decision making on the productivity of various biofuel production pathways. Finally, the proposed exergetic framework could assist engineers and researchers to link biochemical and physical knowledge more robustly and to quantify and elucidate the general purpose of productivity and renewability.

  • Exergy analysis for decision making on operational condition of a continuous photobioreactor for hydrogen production via wgs reaction
    International Journal of Hydrogen Energy, 2016
    Co-Authors: Mortaza Aghbashlo, Seyed Sina Hosseini, Meisam Tabatabaei, Habibollah Younesi, Ghasem D. Najafpour
    Abstract:

    Abstract In the present study, continuous photobiological hydrogen production from syngas through the water gas shift (WGS) reaction by Rhodospirillum rubrum was thermodynamically scrutinized using both conventional Exergy and eco-Exergy Concepts for the first time. These analyses were applied for decision making on liquid media flow rate and agitation speed with respect to the sustainability and productivity issues. The maximum process exergetic efficiency was found to be 22.27% and 22.09% using the conventional Exergy and eco-Exergy Concepts, respectively, at a liquid media flow rate of 12 mL/min and an agitation speed of 500 rpm as the best operational conditions. In general, the eco-exergetic parameters and their conventional Exergy counterparts did not show significant differences due to the slow growth rate of the microorganisms in the bioreactor. However, eco-Exergy Concept would be strongly recommended to apply for analyzing such renewable fuel production systems containing living organisms. Moreover, this work demonstrated the merits of exergetic indicators based on the second law of thermodynamics over the single process yield in assessing photobiological hydrogen production. The results obtained also showed that Exergy analysis could facilitate on-going attempts to increase the sustainability and productivity of large-scale photobiological hydrogen production systems.

  • Exergy analysis of biohydrogen production from various carbon sources via anaerobic photosynthetic bacteria rhodospirillum rubrum
    Energy, 2015
    Co-Authors: Seyed Sina Hosseini, Mortaza Aghbashlo, Meisam Tabatabaei, Habibollah Younesi, Ghasem D. Najafpour
    Abstract:

    In this study, Exergy analysis of batch biohydrogen production through WGS (water–gas shift) reaction using an anaerobic photosynthetic bacteria Rhodospirillum rubrum was carried out for the first time. Various carbon sources including formate, acetate, malate, glucose, fructose, and sucrose were applied to support microbial growth in the presence of CO-rich syngas. The microorganisms utilized carbon monoxide and produced molecular hydrogen concurrently. The process was analyzed based on both conventional Exergy and eco-Exergy Concepts for determining the exergetic parameters i.e., Exergy destruction and Exergy efficiency. Unlike the Exergy efficiency, the Exergy destruction based on the eco-Exergy Concept was remarkably lower than what obtained via the conventional Exergy theory. Minimum normalized Exergy destruction values of 189.67 and 181.40 kJ/kJ H2 were achieved for acetate as substrate using the Exergy and eco-Exergy approaches, respectively. In better words, acetate was identified as the most appropriate carbon source for biohydrogen production from the Exergy point of view. Finally, the findings of this study confirmed that Exergy analysis could be employed as an adaptable framework to determine and compare the renewability of biological hydrogen production using different routes in order to decide on the most suitable approach and conditions.

  • Thermodynamic evaluation of a photobioreactor for hydrogen production from syngas via a locally isolated Rhodopseudomonas palustris PT
    International Journal of Hydrogen Energy, 2015
    Co-Authors: Seyed Sina Hosseini, Mortaza Aghbashlo, Meisam Tabatabaei, Ghasem D. Najafpour, Habibollah Younesi
    Abstract:

    Abstract This paper proposes a thermodynamic framework based on Exergy and eco-Exergy Concepts for biological hydrogen production from CO-enriched gas via a locally isolated photosynthetic bacterium Rhodopseudomonas palustris PT. In order to achieve a deeper understanding on the bioreactor performance, exergetic parameters like Exergy destruction, Exergy efficiency, and sustainability index for the bioreactor were determined using both Concepts at different acetate concentrations as a carbon source ranging from 0 to 3 g/L. The exergetic results based on both Concepts remarkably diverged from each other due to the inclusion of the work of information carried by the genomes of living organisms in the eco-Exergy Concept. The sustainable dosage of sodium acetate was found to be 1.5 g/L for efficient and eco-friendly bioconversion of harmful carbon monoxide to hydrogen and carbon dioxide through the water-gas shift (WGS) reaction. The methodologies applied herein revealed the benefits of applying Exergy analysis for the design and optimization of industrial-scale bioreactors to attain more cost-effective and eco-friendly biohydrogen production. Consequently, the photobiological hydrogen production can be taken into account as a sustainable alternative fuel to the non-renewable fossil resources by minimizing the thermodynamics irreversibilities.