The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Nehir Tokgoz - One of the best experts on this subject based on the ideXlab platform.
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the performance assessment of a combined organic rankine vapor compression refrigeration cycle aided hydrogen liquefaction
International Journal of Hydrogen Energy, 2018Co-Authors: Önder Kaşka, Ceyhun Yilmaz, Nehir TokgozAbstract:Abstract In this study, the performance of the combined cooling cycle with the Organic Rankine power cycle, which provides cooling of the hydrogen at the compressor inlet which compresses the constant temperature in the Claude cycle used for hydrogen liquefaction, on the system is examined. The Organic Rankine combined cooling cycle was considered to be using a geothermal source with a flow rate of 120 kg/s at a temperature of 200 °C. The first and second law performance evaluations of the whole system were made depending on the heat energy at different levels taken from the geothermal source. The thermodynamic analysis of the equipment making up the system has been done in detail. The temperature values at which the hydrogen can be effectively cooled were determined in the presented combined system. The Efficiency Coefficient of the total system was calculated based on varying pre-cooling values. As a result of the study, it was determined that cold entry of hydrogen into the Claude cycle reduced the energy consumption required for liquefaction. Amount of hydrogen cooled to specified temperature increase by increase in mass flow of geothermal water and its temperature. Liquefaction cost is calculated to be 0.995 $/kg H2 and electricity produced by itself is calculated to be 0.025 $/kWh by the new model of liquefaction system. Cost of the liquefaction in the proposed system is about 39.7% lower than direct value of hydrogen liquefaction of 1.650 $/kg given in the literature.
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the performance assessment of a combined organic rankine vapor compression refrigeration cycle aided hydrogen liquefaction
INTERNATIONAL ADVANCED RESEARCHES and ENGINEERING CONGRESS (IAREC 2017), 2017Co-Authors: Önder Kaşka, Ceyhun Yilmaz, Nehir TokgozAbstract:In this study, the performance of the combined cooling cycle with the Organic Rankine power cycle, which provides cooling of the hydrogen at the compressor outlet which compresses the constant temperature in the Claude cycle used for hydrogen liquefaction, on the system is examined. The Organic Rankine combined cooling cycle was considered to be using a geothermal source with a flow rate of 150 kg / s at a temperature of 200 ° C. The first and second law performance evaluations of the whole system were made depending on the heat energy at different levels taken from the geothermal source. The thermodynamic analysis of the equipment making up the system has been done in detail. The temperature values at which the hydrogen can be effectively cooled were determined in the presented combined system. The Efficiency Coefficient of the total system was calculated based on varying pre-cooling values. As a result of the study, it was determined that cold entry of hydrogen into the Claude cycle reduced the energy consumption required for fluidization.
Önder Kaşka - One of the best experts on this subject based on the ideXlab platform.
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the performance assessment of a combined organic rankine vapor compression refrigeration cycle aided hydrogen liquefaction
International Journal of Hydrogen Energy, 2018Co-Authors: Önder Kaşka, Ceyhun Yilmaz, Nehir TokgozAbstract:Abstract In this study, the performance of the combined cooling cycle with the Organic Rankine power cycle, which provides cooling of the hydrogen at the compressor inlet which compresses the constant temperature in the Claude cycle used for hydrogen liquefaction, on the system is examined. The Organic Rankine combined cooling cycle was considered to be using a geothermal source with a flow rate of 120 kg/s at a temperature of 200 °C. The first and second law performance evaluations of the whole system were made depending on the heat energy at different levels taken from the geothermal source. The thermodynamic analysis of the equipment making up the system has been done in detail. The temperature values at which the hydrogen can be effectively cooled were determined in the presented combined system. The Efficiency Coefficient of the total system was calculated based on varying pre-cooling values. As a result of the study, it was determined that cold entry of hydrogen into the Claude cycle reduced the energy consumption required for liquefaction. Amount of hydrogen cooled to specified temperature increase by increase in mass flow of geothermal water and its temperature. Liquefaction cost is calculated to be 0.995 $/kg H2 and electricity produced by itself is calculated to be 0.025 $/kWh by the new model of liquefaction system. Cost of the liquefaction in the proposed system is about 39.7% lower than direct value of hydrogen liquefaction of 1.650 $/kg given in the literature.
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the performance assessment of a combined organic rankine vapor compression refrigeration cycle aided hydrogen liquefaction
INTERNATIONAL ADVANCED RESEARCHES and ENGINEERING CONGRESS (IAREC 2017), 2017Co-Authors: Önder Kaşka, Ceyhun Yilmaz, Nehir TokgozAbstract:In this study, the performance of the combined cooling cycle with the Organic Rankine power cycle, which provides cooling of the hydrogen at the compressor outlet which compresses the constant temperature in the Claude cycle used for hydrogen liquefaction, on the system is examined. The Organic Rankine combined cooling cycle was considered to be using a geothermal source with a flow rate of 150 kg / s at a temperature of 200 ° C. The first and second law performance evaluations of the whole system were made depending on the heat energy at different levels taken from the geothermal source. The thermodynamic analysis of the equipment making up the system has been done in detail. The temperature values at which the hydrogen can be effectively cooled were determined in the presented combined system. The Efficiency Coefficient of the total system was calculated based on varying pre-cooling values. As a result of the study, it was determined that cold entry of hydrogen into the Claude cycle reduced the energy consumption required for fluidization.
Auli Niemi - One of the best experts on this subject based on the ideXlab platform.
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effects of permeability heterogeneity on co2 injectivity and storage Efficiency Coefficient
Greenhouse Gases-Science and Technology, 2016Co-Authors: Liang Tian, Zhibing Yang, Fritjof Fagerlund, Auli NiemiAbstract:We study the dependency of CO 2 storage Efficiency Coefficient (E) and injectivity index (I inj ) on the geostatistical parameters of the permeability field. CO 2 injection simulations are conducted for multiple realizations of log‐normally distributed permeability fields parameterized by log permeability standard deviation (σ) and dimensionless horizontal correlation length (λ). Results show that the injectivity index increases with increasing λ, the magnitude of the effect depending on σ. Increasing σ leads to poorer injectivity for cases with small λ, but improves injectivity when λ is large. Further analysis indicates that the enhancing effect of σ on injectivity can be attributed to cases with channelized flow, while the decrease effect of σ is seen in more dispersive flow regime. The dependence of injectivity on both λ and σ is captured with a linear correlation between I inj and a parameter group , where ξ is a dimensionless scaling parameter. The storage Efficiency Coefficient, on the other hand, decreases with both increasing σ and λ, and a simple linear fit is found between E and the parameter group λσ-super-2, a well‐established heterogeneity parameter group describing e.g. macro‐dispersivity in solute transport studies. These relationships provide potentially useful tools for the preliminary evaluation of a site. Future studies should address the validity of the relationships in alternative injection scenarios and domain geometries. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
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effects of permeability heterogeneity on co2 injectivity and storage Efficiency Coefficient
Greenhouse Gases-Science and Technology, 2016Co-Authors: Liang Tian, Zhibing Yang, Fritjof Fagerlund, Auli NiemiAbstract:This work presents model development and model analyses of CO2 storage in deep saline aquifers. The goal has been two-fold, firstly to develop models and address the system behaviour under geological heterogeneity, second to tackle the issues related to problem scale as modelling of the CO2 storage systems can become prohibitively complex when large systems are considered.The work starts from a Monte Carlo analysis of heterogeneous 2D domains with a focus on the sensitivity of two CO2 storage performance measurements, namely, the injectivity index (Iinj) and storage Efficiency Coefficient (E), on parameters characterizing heterogeneity. It is found that E and Iinj are determined by two different parameter groups which both include correlation length (λ) and standard deviation (σ) of the permeability. Next, the issue of upscaling is addressed by modelling a heterogeneous system with multi-modal heterogeneity and an upscaling scheme of the constitutive relationships is proposed to enable the numerical simulation to be done using a coarser geological mesh built for a larger domain. Finally, in order to better address stochastically heterogeneous systems, a new method for model simulations and uncertainty analysis based on a Gaussian processes emulator is introduced. Instead of conventional point estimates this Bayesian approach can efficiently approximate cumulative distribution functions for the selected outputs which are CO2 breakthrough time and its total mass. After focusing on reservoir behaviour in small domains and modelling the heterogeneity effects in them, the work moves to predictive modelling of large scale CO2 storage systems. To maximize the confidence in the model predictions, a set of different modelling approaches of varying complexity is employed, including a semi-analytical model, a sharp-interface vertical equilibrium (VE) model and a TOUGH2MP / ECO2N model. Based on this approach, the CO2 storage potential of two large scale sites is modelled, namely the South Scania site, Sweden and the Dalders Monocline in the Baltic Sea basin.The methodologies developed and demonstrated in this work enable improved analyses of CO2 geological storage at both small and large scales, including better approaches to address medium heterogeneity. Finally, recommendations for future work are also discussed.
Ceyhun Yilmaz - One of the best experts on this subject based on the ideXlab platform.
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the performance assessment of a combined organic rankine vapor compression refrigeration cycle aided hydrogen liquefaction
International Journal of Hydrogen Energy, 2018Co-Authors: Önder Kaşka, Ceyhun Yilmaz, Nehir TokgozAbstract:Abstract In this study, the performance of the combined cooling cycle with the Organic Rankine power cycle, which provides cooling of the hydrogen at the compressor inlet which compresses the constant temperature in the Claude cycle used for hydrogen liquefaction, on the system is examined. The Organic Rankine combined cooling cycle was considered to be using a geothermal source with a flow rate of 120 kg/s at a temperature of 200 °C. The first and second law performance evaluations of the whole system were made depending on the heat energy at different levels taken from the geothermal source. The thermodynamic analysis of the equipment making up the system has been done in detail. The temperature values at which the hydrogen can be effectively cooled were determined in the presented combined system. The Efficiency Coefficient of the total system was calculated based on varying pre-cooling values. As a result of the study, it was determined that cold entry of hydrogen into the Claude cycle reduced the energy consumption required for liquefaction. Amount of hydrogen cooled to specified temperature increase by increase in mass flow of geothermal water and its temperature. Liquefaction cost is calculated to be 0.995 $/kg H2 and electricity produced by itself is calculated to be 0.025 $/kWh by the new model of liquefaction system. Cost of the liquefaction in the proposed system is about 39.7% lower than direct value of hydrogen liquefaction of 1.650 $/kg given in the literature.
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the performance assessment of a combined organic rankine vapor compression refrigeration cycle aided hydrogen liquefaction
INTERNATIONAL ADVANCED RESEARCHES and ENGINEERING CONGRESS (IAREC 2017), 2017Co-Authors: Önder Kaşka, Ceyhun Yilmaz, Nehir TokgozAbstract:In this study, the performance of the combined cooling cycle with the Organic Rankine power cycle, which provides cooling of the hydrogen at the compressor outlet which compresses the constant temperature in the Claude cycle used for hydrogen liquefaction, on the system is examined. The Organic Rankine combined cooling cycle was considered to be using a geothermal source with a flow rate of 150 kg / s at a temperature of 200 ° C. The first and second law performance evaluations of the whole system were made depending on the heat energy at different levels taken from the geothermal source. The thermodynamic analysis of the equipment making up the system has been done in detail. The temperature values at which the hydrogen can be effectively cooled were determined in the presented combined system. The Efficiency Coefficient of the total system was calculated based on varying pre-cooling values. As a result of the study, it was determined that cold entry of hydrogen into the Claude cycle reduced the energy consumption required for fluidization.
Liang Tian - One of the best experts on this subject based on the ideXlab platform.
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effects of permeability heterogeneity on co2 injectivity and storage Efficiency Coefficient
Greenhouse Gases-Science and Technology, 2016Co-Authors: Liang Tian, Zhibing Yang, Fritjof Fagerlund, Auli NiemiAbstract:We study the dependency of CO 2 storage Efficiency Coefficient (E) and injectivity index (I inj ) on the geostatistical parameters of the permeability field. CO 2 injection simulations are conducted for multiple realizations of log‐normally distributed permeability fields parameterized by log permeability standard deviation (σ) and dimensionless horizontal correlation length (λ). Results show that the injectivity index increases with increasing λ, the magnitude of the effect depending on σ. Increasing σ leads to poorer injectivity for cases with small λ, but improves injectivity when λ is large. Further analysis indicates that the enhancing effect of σ on injectivity can be attributed to cases with channelized flow, while the decrease effect of σ is seen in more dispersive flow regime. The dependence of injectivity on both λ and σ is captured with a linear correlation between I inj and a parameter group , where ξ is a dimensionless scaling parameter. The storage Efficiency Coefficient, on the other hand, decreases with both increasing σ and λ, and a simple linear fit is found between E and the parameter group λσ-super-2, a well‐established heterogeneity parameter group describing e.g. macro‐dispersivity in solute transport studies. These relationships provide potentially useful tools for the preliminary evaluation of a site. Future studies should address the validity of the relationships in alternative injection scenarios and domain geometries. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
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effects of permeability heterogeneity on co2 injectivity and storage Efficiency Coefficient
Greenhouse Gases-Science and Technology, 2016Co-Authors: Liang Tian, Zhibing Yang, Fritjof Fagerlund, Auli NiemiAbstract:This work presents model development and model analyses of CO2 storage in deep saline aquifers. The goal has been two-fold, firstly to develop models and address the system behaviour under geological heterogeneity, second to tackle the issues related to problem scale as modelling of the CO2 storage systems can become prohibitively complex when large systems are considered.The work starts from a Monte Carlo analysis of heterogeneous 2D domains with a focus on the sensitivity of two CO2 storage performance measurements, namely, the injectivity index (Iinj) and storage Efficiency Coefficient (E), on parameters characterizing heterogeneity. It is found that E and Iinj are determined by two different parameter groups which both include correlation length (λ) and standard deviation (σ) of the permeability. Next, the issue of upscaling is addressed by modelling a heterogeneous system with multi-modal heterogeneity and an upscaling scheme of the constitutive relationships is proposed to enable the numerical simulation to be done using a coarser geological mesh built for a larger domain. Finally, in order to better address stochastically heterogeneous systems, a new method for model simulations and uncertainty analysis based on a Gaussian processes emulator is introduced. Instead of conventional point estimates this Bayesian approach can efficiently approximate cumulative distribution functions for the selected outputs which are CO2 breakthrough time and its total mass. After focusing on reservoir behaviour in small domains and modelling the heterogeneity effects in them, the work moves to predictive modelling of large scale CO2 storage systems. To maximize the confidence in the model predictions, a set of different modelling approaches of varying complexity is employed, including a semi-analytical model, a sharp-interface vertical equilibrium (VE) model and a TOUGH2MP / ECO2N model. Based on this approach, the CO2 storage potential of two large scale sites is modelled, namely the South Scania site, Sweden and the Dalders Monocline in the Baltic Sea basin.The methodologies developed and demonstrated in this work enable improved analyses of CO2 geological storage at both small and large scales, including better approaches to address medium heterogeneity. Finally, recommendations for future work are also discussed.
