A novel large-scale plant for hydrogen liquefying is proposed and analyzed. The liquid hydrogen p... more A novel large-scale plant for hydrogen liquefying is proposed and analyzed. The liquid hydrogen production rate of the proposed plant is 100 tons per day to provide the required LH 2 for a large urban area with 100,000e200,000 hydrogen vehicles supply. In the precooling section of the process, a new mixed refrigerant (MR) refrigeration cycle, combined with a JouleeBrayton refrigeration cycle, precool gaseous hydrogen feed from 25 C to the temperature À198.2 C. A new refrigeration system with six simple LindeeHampson cascade cycles cools low-temperature gaseous hydrogen from À198.2 C to temperature À252.2 C. The process specific energy consumption (SEC) is 7:69 kWh=kg LH2 which minimum value is 2:89 kWh=kg LH2 in ideal conditions. The exergy efficiency of the system is 39.5%, which is considerably higher than the existing hydrogen liquefier plants around the world. However, assuming more efficiency values for the equipment can improve it. The energy analysis specifies that coefficient of performance (COP) of the process is 0.1710 which is a high quantity of its kind between other similar processes. Effect of various refrigerant components concentration, discharge pressure of the high pressure compressors of the pre-cooling section, and hydrogen feed pressure on the process COP, exergy efficiency, and SEC are investigated. After that, a new MR will be offered for the cryogenic section of the plant. The system improvements are considerable comparing to current hydrogen liquefying plants, therefore, the proposed conceptual system can be used for future hydrogen liquefaction plants design.
A cryogenic-based module is developed for the separation of the hydrogen from a feed gas mixture ... more A cryogenic-based module is developed for the separation of the hydrogen from a feed gas mixture including nitrogen and linear branched or cyclic C 1 À C 6 hydrocarbons. The feed gas mixture is initially separated in a network of heat exchangers and phase separators to produce hydrogen-rich and hydrogen-lean streams. The hydrogen-enrich stream is extracted from the cryogenic separation heat exchangers and the hydrogen-lean stream is processed through the cryogenic sections to remove non-hydrogen components and produce aromatic, low pressure, and high-pressure fuel streams. A Joule-Bryton propane refrigeration cycle and an auxiliary nitrogen refrigeration stream supply the required cryogenic streams. The process is energy and exergy analyzed and results show that the more than 88.4% of exergy destruction occurred in heat exchangers and the valves have the least role in exergy destruction. Moreover, sensitivity analysis shows that when the mole fraction of hydrogen in feed gas increases by 60.0%, the specific energy decreases by 38.0%, the required power increases by 68.6%, the exergy efficiency reduces by 58.3%, and the required heat increases by 60.0%. As well as, when the pressure of stream 23 increases by 10%, the reduction of exergy efficiency is 9.2%, the promotion of specific energy is 3.0%, the reduction of hydrogen recovery rate is 0.08%, and the increase of nitrogen refrigeration capacity is 10.60%. Therefore, a comprehensive view is needed to change the operational parameters to achieve the desired results. The proposed module may be combined with many other gas upgrading systems.
A novel structure for hydrogen liquefaction is developed and thermodynamically analyzed. The modi... more A novel structure for hydrogen liquefaction is developed and thermodynamically analyzed. The modified structure, which produces approximately 290 tons of liquid hydrogen (LH 2 Þ per day, consists of a basic hydrogen liquefier system, an organic Rankine cycle, an absorption refrigeration system, and solar parabolic dishes. The new approach of simultaneous considering of exergy destruction rate and exergy efficiency is used to analyze the system, which results in lower energy consumption and higher exergy efficiency. Accordingly, the COP of the plant is calculated as 0.2002 and it consumes 4.02 kWh =kg LH2 that is 8.93 percent less than the basic liquefier. Moreover, the overall exergy efficiency of it is 73.57% is 24.60% more than the basic system one. As well as, results indicate that the cryogenic sector of the process consumes 73% of the total consumed energy. Furthermore, exergy analysis shows that the most exergy destruction occurs in the solar collectors (43.59%) and heat exchangers (40.23%), and when the exergy efficiency varies 1.9% during a typical day, the exergy destruction change will be 9.5%. As well as, sensitive analysis shows that when solar energy increases by 204% due to adding more solar collectors, boilers energy decreases by 59%. Moreover, when the number of the collectors doubles, the production rates and the energy consumption of the process are also doubled. However, more power will be needed that will increase the operating cost of the liquefier. Therefore, an exergy-economy analysis may be used to address the optimum solutions.
3E)exergy/exergoeconomic/exergoenvironmental) analysis is considered to evaluate a novel hydrogen... more 3E)exergy/exergoeconomic/exergoenvironmental) analysis is considered to evaluate a novel hydrogen liquefaction process. The proposed process is a simple Claude cycle combined with two absorption refrigeration systems (ARSs). The mass flow rate of the liquid hydrogen (LH2) production is about 260 tones per day and the specific energy consumption (SEC) and the exergy efficiency of the system are12.7 kWh/kgLH2 and 31.6% respectively. The results show that the HX-201 and HX-203 heat exchangers have the highest total environmental impact and total exergy cost. Therefore, they are in the priority of improving to achieve better performance for overall the process. In addition, the P-101 pump has the highest exergoeconomic and exergoenvairomental coefficient. Therefore, its capital investment cost and its environmental impact should be reduced to decrease the cost and environmental impact of the whole system. Furthermore, the HX-201 heat exchanger has the lowest exergoeconomic and exergoenvairomental coefficient. Therefore, the technical performance of this device should be improved to reduce the cost and environmental impact of the whole system. In addition, a 3D sensitivity analysis is investigated to consider simultaneously the interaction between technical, economic, and environmental aspects of the system. Accordingly, there is an optimum value for the isentropic efficiency of the C-1 compressor that should be examined, and the more/fewer is its pressure ratio, the more/fewer are its exergy costs and/or environmental impacts. Moreover, whilst an optimum pressure ratio should be found out for EXP-2 expander, a higher isentropic efficiency definitely decreases its exergy cost and environmental impact. In addition, the less/more is the temperature approach Tmin of HX-1 heat exchanger, the less/more are its exergy costs and/or its environmental impacts. As well as, its input pressure should be maximized to achieve minimum exergy costs and environmental impacts of the component. Finally, tower pressure should be raised as much as possible to achieve the least exergy costs and environmental impacts of the T-101 generator. However, its inlet temperature has an optimum value that should be found out.
• Large-scale hydrogen liquefaction (LHL) methods are chronicled. • A novel classification of hyd... more • Large-scale hydrogen liquefaction (LHL) methods are chronicled. • A novel classification of hydrogen liquefaction systems is introduced. • Hybrid conceptual hydrogen liquefaction plants are reviewed. • Specific energy consumption (SEC) of hydrogen liquefiers is discussed. A B S T R A C T Large-scale hydrogen liquefaction (LHL) methods and different approaches of the configuration of hydrogen liquefaction cycles are chronicled. History landmarks of permanent gases liquefaction are quick reviewed and the basic hydrogen liquefaction cycles, the existing in-service LHL plants around the world, and LHL conceptual proposed plants, including the state of the art plants, are recorded and categorized based on the systems' main parameters. In addition, a novel classification of hydrogen liquefaction systems in terms of heat exchange and expansion process method is introduced. As well as, the authors infer that renewable energy technologies section should be added to the old sectioning of the hydrogen liquefaction plants. In addition, hybrid conceptual hydrogen liquefaction plants, combining with renewable power cycles are reviewed and the increasing contribution of this new approach is demonstrated. Finally, the operational costs of the plants considering the systems' efficiency are examined, and a trend in specific energy consumption (SEC) and exergy efficiency of hydrogen liquefiers is discussed. Accordingly, considering the existing technologies, SEC reduction of hydrogen lique-faction will not be abrupt in near future and it will remain within the range of 5-8 kWh/kg LH2. Moreover, exploiting of isentropic expansion processes instead of isenthalpic one, cascading of refrigerating cycles, using of new mixed refrigerants as working fluid of refrigeration cycles, and hybridization of renewable energy power cycles to refrigeration cycles are the main four growing approaches in the hydrogen liquefaction context.
Hydrogen liquefaction processes have effective function in the hydrogen supply chain. However low... more Hydrogen liquefaction processes have effective function in the hydrogen supply chain. However low efficiency and high liquefaction costs are still the most important concerns about the liquefaction plants. In this study a new configuration for a hydrogen liquefier process is proposed and energy-exergy analyzed. The production rate of the liquid hydrogen ðLH 2 Þ is 90 tons per day that can supply the required LH 2 of at least 90 k-180 k hydrogen vehicles in an urban area that results in the reduction of pollutions caused by carbon dioxide emission. The process is simulated in Aspen HYSYS simulator. In addition, it is optimized thorough a trial and error approach that is a functional and simple method of complicated systems analysis. The process includes a mixed refrigerant (MR) refrigeration cycle that precools feed gas hydrogen from 25 C temperature to À199:9 C temperature. A new MR is used in a cascade Joule-Brayton cycle that deep-cools the low-temperature gaseous hydrogen from À199:9 C temperature to À252:2 C temperature in the cryogenic section of the plant. The novel process involves also an absorption refrigeration system (ARS) that cools some hydrogen streams in the precooling and cryogenic sections of the process. The consumed energy per kilogram of produced LH 2 is achieved as 6:47 kWh. This quantity is 2:89 kWh in the ideal conditions. The exergy efficiency of the plant is evaluated to be 45.5% that is significantly more than the exergy efficiency of the in operating hydrogen liquefiers in the world. The energy analysis reveals that the coefficient of performance (COP) of the overall system is 0.2034. The achieved COP is a higher amount in compare to the other similar processes. A sensitivity analysis is done to show the effect of the various operation conditions of the process on the features of the plant. Accordingly, the optimum mass flow of the ARS is determined as 207 kg=s for the proposed configuration. As well as, the effect of the change in the temperature approach of the heat exchangers and the changes in the adiabatic efficiency of the compressors and expanders on the SEC, COP, and the exergy efficiency of the overall plant is discussed. Furthermore, financial analysis of the plant estimates the capital expenditures (CAPEX), energy expenditures (EEX), and operational and maintenance expenditures (OMEX) as 25413 V 2000 , 7370 V 2000 , and 2033 V 2000 respectively. These can be specially improved be improving of the exergy efficiency of the plant. The results implicates that the proposed configuration has better performance indicators than the in-service liquefiers. Therefore, LHL plant manufacturer can be considered it in the design and development of new plants. As well as, researchers may utilize its operating conditions to improve the proposed processes.
Large-scale hydrogen liquefaction Mixed-refrigerant Cascade refrigeration Cryogenic Deep refriger... more Large-scale hydrogen liquefaction Mixed-refrigerant Cascade refrigeration Cryogenic Deep refrigeration a b s t r a c t A novel large-scale plant for hydrogen liquefying is proposed and analyzed. The liquid hydrogen production rate of the proposed plant is 100 tons per day to provide the required LH 2 for a large urban area with 100,000e200,000 hydrogen vehicles supply. In the pre-cooling section of the process, a new mixed refrigerant (MR) refrigeration cycle, combined with a JouleeBrayton refrigeration cycle, precool gaseous hydrogen feed from 25 C to the temperature À198.2 C. A new refrigeration system with six simple LindeeHampson cascade cycles cools low-temperature gaseous hydrogen from À198.2 C to temperature À252.2 C. The process specific energy consumption (SEC) is 7:69 kWh=kg LH2 which minimum value is 2:89 kWh=kg LH2 in ideal conditions. The exergy efficiency of the system is 39.5%, which is considerably higher than the existing hydrogen liquefier plants around the world. However, assuming more efficiency values for the equipment can improve it. The energy analysis specifies that coefficient of performance (COP) of the process is 0.1710 which is a high quantity of its kind between other similar processes. Effect of various refrigerant components concentration, discharge pressure of the high pressure compres-sors of the pre-cooling section, and hydrogen feed pressure on the process COP, exergy efficiency, and SEC are investigated. After that, a new MR will be offered for the cryogenic section of the plant. The system improvements are considerable comparing to current hydrogen liquefying plants, therefore, the proposed conceptual system can be used for future hydrogen liquefaction plants design.
• Large-scale hydrogen liquefaction (LHL) methods are chronicled. • A novel classification of hyd... more • Large-scale hydrogen liquefaction (LHL) methods are chronicled. • A novel classification of hydrogen liquefaction systems is introduced. • Hybrid conceptual hydrogen liquefaction plants are reviewed. • Specific energy consumption (SEC) of hydrogen liquefiers is discussed. A B S T R A C T Large-scale hydrogen liquefaction (LHL) methods and different approaches of the configuration of hydrogen liquefaction cycles are chronicled. History landmarks of permanent gases liquefaction are quick reviewed and the basic hydrogen liquefaction cycles, the existing in-service LHL plants around the world, and LHL conceptual proposed plants, including the state of the art plants, are recorded and categorized based on the systems' main parameters. In addition, a novel classification of hydrogen liquefaction systems in terms of heat exchange and expansion process method is introduced. As well as, the authors infer that renewable energy technologies section should be added to the old sectioning of the hydrogen liquefaction plants. In addition, hybrid conceptual hydrogen liquefaction plants, combining with renewable power cycles are reviewed and the increasing contribution of this new approach is demonstrated. Finally, the operational costs of the plants considering the systems' efficiency are examined, and a trend in specific energy consumption (SEC) and exergy efficiency of hydrogen liquefiers is discussed. Accordingly, considering the existing technologies, SEC reduction of hydrogen lique-faction will not be abrupt in near future and it will remain within the range of 5–8 kWh/kg LH2. Moreover, exploiting of isentropic expansion processes instead of isenthalpic one, cascading of refrigerating cycles, using of new mixed refrigerants as working fluid of refrigeration cycles, and hybridization of renewable energy power cycles to refrigeration cycles are the main four growing approaches in the hydrogen liquefaction context.
A novel large-scale plant for hydrogen liquefying is proposed and analyzed. The liquid hydrogen p... more A novel large-scale plant for hydrogen liquefying is proposed and analyzed. The liquid hydrogen production rate of the proposed plant is 100 tons per day to provide the required LH 2 for a large urban area with 100,000e200,000 hydrogen vehicles supply. In the precooling section of the process, a new mixed refrigerant (MR) refrigeration cycle, combined with a JouleeBrayton refrigeration cycle, precool gaseous hydrogen feed from 25 C to the temperature À198.2 C. A new refrigeration system with six simple LindeeHampson cascade cycles cools low-temperature gaseous hydrogen from À198.2 C to temperature À252.2 C. The process specific energy consumption (SEC) is 7:69 kWh=kg LH2 which minimum value is 2:89 kWh=kg LH2 in ideal conditions. The exergy efficiency of the system is 39.5%, which is considerably higher than the existing hydrogen liquefier plants around the world. However, assuming more efficiency values for the equipment can improve it. The energy analysis specifies that coefficient of performance (COP) of the process is 0.1710 which is a high quantity of its kind between other similar processes. Effect of various refrigerant components concentration, discharge pressure of the high pressure compressors of the pre-cooling section, and hydrogen feed pressure on the process COP, exergy efficiency, and SEC are investigated. After that, a new MR will be offered for the cryogenic section of the plant. The system improvements are considerable comparing to current hydrogen liquefying plants, therefore, the proposed conceptual system can be used for future hydrogen liquefaction plants design.
A cryogenic-based module is developed for the separation of the hydrogen from a feed gas mixture ... more A cryogenic-based module is developed for the separation of the hydrogen from a feed gas mixture including nitrogen and linear branched or cyclic C 1 À C 6 hydrocarbons. The feed gas mixture is initially separated in a network of heat exchangers and phase separators to produce hydrogen-rich and hydrogen-lean streams. The hydrogen-enrich stream is extracted from the cryogenic separation heat exchangers and the hydrogen-lean stream is processed through the cryogenic sections to remove non-hydrogen components and produce aromatic, low pressure, and high-pressure fuel streams. A Joule-Bryton propane refrigeration cycle and an auxiliary nitrogen refrigeration stream supply the required cryogenic streams. The process is energy and exergy analyzed and results show that the more than 88.4% of exergy destruction occurred in heat exchangers and the valves have the least role in exergy destruction. Moreover, sensitivity analysis shows that when the mole fraction of hydrogen in feed gas increases by 60.0%, the specific energy decreases by 38.0%, the required power increases by 68.6%, the exergy efficiency reduces by 58.3%, and the required heat increases by 60.0%. As well as, when the pressure of stream 23 increases by 10%, the reduction of exergy efficiency is 9.2%, the promotion of specific energy is 3.0%, the reduction of hydrogen recovery rate is 0.08%, and the increase of nitrogen refrigeration capacity is 10.60%. Therefore, a comprehensive view is needed to change the operational parameters to achieve the desired results. The proposed module may be combined with many other gas upgrading systems.
A novel structure for hydrogen liquefaction is developed and thermodynamically analyzed. The modi... more A novel structure for hydrogen liquefaction is developed and thermodynamically analyzed. The modified structure, which produces approximately 290 tons of liquid hydrogen (LH 2 Þ per day, consists of a basic hydrogen liquefier system, an organic Rankine cycle, an absorption refrigeration system, and solar parabolic dishes. The new approach of simultaneous considering of exergy destruction rate and exergy efficiency is used to analyze the system, which results in lower energy consumption and higher exergy efficiency. Accordingly, the COP of the plant is calculated as 0.2002 and it consumes 4.02 kWh =kg LH2 that is 8.93 percent less than the basic liquefier. Moreover, the overall exergy efficiency of it is 73.57% is 24.60% more than the basic system one. As well as, results indicate that the cryogenic sector of the process consumes 73% of the total consumed energy. Furthermore, exergy analysis shows that the most exergy destruction occurs in the solar collectors (43.59%) and heat exchangers (40.23%), and when the exergy efficiency varies 1.9% during a typical day, the exergy destruction change will be 9.5%. As well as, sensitive analysis shows that when solar energy increases by 204% due to adding more solar collectors, boilers energy decreases by 59%. Moreover, when the number of the collectors doubles, the production rates and the energy consumption of the process are also doubled. However, more power will be needed that will increase the operating cost of the liquefier. Therefore, an exergy-economy analysis may be used to address the optimum solutions.
3E)exergy/exergoeconomic/exergoenvironmental) analysis is considered to evaluate a novel hydrogen... more 3E)exergy/exergoeconomic/exergoenvironmental) analysis is considered to evaluate a novel hydrogen liquefaction process. The proposed process is a simple Claude cycle combined with two absorption refrigeration systems (ARSs). The mass flow rate of the liquid hydrogen (LH2) production is about 260 tones per day and the specific energy consumption (SEC) and the exergy efficiency of the system are12.7 kWh/kgLH2 and 31.6% respectively. The results show that the HX-201 and HX-203 heat exchangers have the highest total environmental impact and total exergy cost. Therefore, they are in the priority of improving to achieve better performance for overall the process. In addition, the P-101 pump has the highest exergoeconomic and exergoenvairomental coefficient. Therefore, its capital investment cost and its environmental impact should be reduced to decrease the cost and environmental impact of the whole system. Furthermore, the HX-201 heat exchanger has the lowest exergoeconomic and exergoenvairomental coefficient. Therefore, the technical performance of this device should be improved to reduce the cost and environmental impact of the whole system. In addition, a 3D sensitivity analysis is investigated to consider simultaneously the interaction between technical, economic, and environmental aspects of the system. Accordingly, there is an optimum value for the isentropic efficiency of the C-1 compressor that should be examined, and the more/fewer is its pressure ratio, the more/fewer are its exergy costs and/or environmental impacts. Moreover, whilst an optimum pressure ratio should be found out for EXP-2 expander, a higher isentropic efficiency definitely decreases its exergy cost and environmental impact. In addition, the less/more is the temperature approach Tmin of HX-1 heat exchanger, the less/more are its exergy costs and/or its environmental impacts. As well as, its input pressure should be maximized to achieve minimum exergy costs and environmental impacts of the component. Finally, tower pressure should be raised as much as possible to achieve the least exergy costs and environmental impacts of the T-101 generator. However, its inlet temperature has an optimum value that should be found out.
• Large-scale hydrogen liquefaction (LHL) methods are chronicled. • A novel classification of hyd... more • Large-scale hydrogen liquefaction (LHL) methods are chronicled. • A novel classification of hydrogen liquefaction systems is introduced. • Hybrid conceptual hydrogen liquefaction plants are reviewed. • Specific energy consumption (SEC) of hydrogen liquefiers is discussed. A B S T R A C T Large-scale hydrogen liquefaction (LHL) methods and different approaches of the configuration of hydrogen liquefaction cycles are chronicled. History landmarks of permanent gases liquefaction are quick reviewed and the basic hydrogen liquefaction cycles, the existing in-service LHL plants around the world, and LHL conceptual proposed plants, including the state of the art plants, are recorded and categorized based on the systems' main parameters. In addition, a novel classification of hydrogen liquefaction systems in terms of heat exchange and expansion process method is introduced. As well as, the authors infer that renewable energy technologies section should be added to the old sectioning of the hydrogen liquefaction plants. In addition, hybrid conceptual hydrogen liquefaction plants, combining with renewable power cycles are reviewed and the increasing contribution of this new approach is demonstrated. Finally, the operational costs of the plants considering the systems' efficiency are examined, and a trend in specific energy consumption (SEC) and exergy efficiency of hydrogen liquefiers is discussed. Accordingly, considering the existing technologies, SEC reduction of hydrogen lique-faction will not be abrupt in near future and it will remain within the range of 5-8 kWh/kg LH2. Moreover, exploiting of isentropic expansion processes instead of isenthalpic one, cascading of refrigerating cycles, using of new mixed refrigerants as working fluid of refrigeration cycles, and hybridization of renewable energy power cycles to refrigeration cycles are the main four growing approaches in the hydrogen liquefaction context.
Hydrogen liquefaction processes have effective function in the hydrogen supply chain. However low... more Hydrogen liquefaction processes have effective function in the hydrogen supply chain. However low efficiency and high liquefaction costs are still the most important concerns about the liquefaction plants. In this study a new configuration for a hydrogen liquefier process is proposed and energy-exergy analyzed. The production rate of the liquid hydrogen ðLH 2 Þ is 90 tons per day that can supply the required LH 2 of at least 90 k-180 k hydrogen vehicles in an urban area that results in the reduction of pollutions caused by carbon dioxide emission. The process is simulated in Aspen HYSYS simulator. In addition, it is optimized thorough a trial and error approach that is a functional and simple method of complicated systems analysis. The process includes a mixed refrigerant (MR) refrigeration cycle that precools feed gas hydrogen from 25 C temperature to À199:9 C temperature. A new MR is used in a cascade Joule-Brayton cycle that deep-cools the low-temperature gaseous hydrogen from À199:9 C temperature to À252:2 C temperature in the cryogenic section of the plant. The novel process involves also an absorption refrigeration system (ARS) that cools some hydrogen streams in the precooling and cryogenic sections of the process. The consumed energy per kilogram of produced LH 2 is achieved as 6:47 kWh. This quantity is 2:89 kWh in the ideal conditions. The exergy efficiency of the plant is evaluated to be 45.5% that is significantly more than the exergy efficiency of the in operating hydrogen liquefiers in the world. The energy analysis reveals that the coefficient of performance (COP) of the overall system is 0.2034. The achieved COP is a higher amount in compare to the other similar processes. A sensitivity analysis is done to show the effect of the various operation conditions of the process on the features of the plant. Accordingly, the optimum mass flow of the ARS is determined as 207 kg=s for the proposed configuration. As well as, the effect of the change in the temperature approach of the heat exchangers and the changes in the adiabatic efficiency of the compressors and expanders on the SEC, COP, and the exergy efficiency of the overall plant is discussed. Furthermore, financial analysis of the plant estimates the capital expenditures (CAPEX), energy expenditures (EEX), and operational and maintenance expenditures (OMEX) as 25413 V 2000 , 7370 V 2000 , and 2033 V 2000 respectively. These can be specially improved be improving of the exergy efficiency of the plant. The results implicates that the proposed configuration has better performance indicators than the in-service liquefiers. Therefore, LHL plant manufacturer can be considered it in the design and development of new plants. As well as, researchers may utilize its operating conditions to improve the proposed processes.
Large-scale hydrogen liquefaction Mixed-refrigerant Cascade refrigeration Cryogenic Deep refriger... more Large-scale hydrogen liquefaction Mixed-refrigerant Cascade refrigeration Cryogenic Deep refrigeration a b s t r a c t A novel large-scale plant for hydrogen liquefying is proposed and analyzed. The liquid hydrogen production rate of the proposed plant is 100 tons per day to provide the required LH 2 for a large urban area with 100,000e200,000 hydrogen vehicles supply. In the pre-cooling section of the process, a new mixed refrigerant (MR) refrigeration cycle, combined with a JouleeBrayton refrigeration cycle, precool gaseous hydrogen feed from 25 C to the temperature À198.2 C. A new refrigeration system with six simple LindeeHampson cascade cycles cools low-temperature gaseous hydrogen from À198.2 C to temperature À252.2 C. The process specific energy consumption (SEC) is 7:69 kWh=kg LH2 which minimum value is 2:89 kWh=kg LH2 in ideal conditions. The exergy efficiency of the system is 39.5%, which is considerably higher than the existing hydrogen liquefier plants around the world. However, assuming more efficiency values for the equipment can improve it. The energy analysis specifies that coefficient of performance (COP) of the process is 0.1710 which is a high quantity of its kind between other similar processes. Effect of various refrigerant components concentration, discharge pressure of the high pressure compres-sors of the pre-cooling section, and hydrogen feed pressure on the process COP, exergy efficiency, and SEC are investigated. After that, a new MR will be offered for the cryogenic section of the plant. The system improvements are considerable comparing to current hydrogen liquefying plants, therefore, the proposed conceptual system can be used for future hydrogen liquefaction plants design.
• Large-scale hydrogen liquefaction (LHL) methods are chronicled. • A novel classification of hyd... more • Large-scale hydrogen liquefaction (LHL) methods are chronicled. • A novel classification of hydrogen liquefaction systems is introduced. • Hybrid conceptual hydrogen liquefaction plants are reviewed. • Specific energy consumption (SEC) of hydrogen liquefiers is discussed. A B S T R A C T Large-scale hydrogen liquefaction (LHL) methods and different approaches of the configuration of hydrogen liquefaction cycles are chronicled. History landmarks of permanent gases liquefaction are quick reviewed and the basic hydrogen liquefaction cycles, the existing in-service LHL plants around the world, and LHL conceptual proposed plants, including the state of the art plants, are recorded and categorized based on the systems' main parameters. In addition, a novel classification of hydrogen liquefaction systems in terms of heat exchange and expansion process method is introduced. As well as, the authors infer that renewable energy technologies section should be added to the old sectioning of the hydrogen liquefaction plants. In addition, hybrid conceptual hydrogen liquefaction plants, combining with renewable power cycles are reviewed and the increasing contribution of this new approach is demonstrated. Finally, the operational costs of the plants considering the systems' efficiency are examined, and a trend in specific energy consumption (SEC) and exergy efficiency of hydrogen liquefiers is discussed. Accordingly, considering the existing technologies, SEC reduction of hydrogen lique-faction will not be abrupt in near future and it will remain within the range of 5–8 kWh/kg LH2. Moreover, exploiting of isentropic expansion processes instead of isenthalpic one, cascading of refrigerating cycles, using of new mixed refrigerants as working fluid of refrigeration cycles, and hybridization of renewable energy power cycles to refrigeration cycles are the main four growing approaches in the hydrogen liquefaction context.
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Papers by Majid Asadnia
process. The proposed process is a simple Claude cycle combined with two absorption refrigeration systems (ARSs).
The mass flow rate of the liquid hydrogen (LH2) production is about 260 tones per day and the specific energy
consumption (SEC) and the exergy efficiency of the system are12.7 kWh/kgLH2 and 31.6% respectively. The results
show that the HX-201 and HX-203 heat exchangers have the highest total environmental impact and total exergy
cost. Therefore, they are in the priority of improving to achieve better performance for overall the process. In
addition, the P-101 pump has the highest exergoeconomic and exergoenvairomental coefficient. Therefore, its capital
investment cost and its environmental impact should be reduced to decrease the cost and environmental impact
of the whole system. Furthermore, the HX-201 heat exchanger has the lowest exergoeconomic and exergoenvairomental
coefficient. Therefore, the technical performance of this device should be improved to reduce the
cost and environmental impact of the whole system. In addition, a 3D sensitivity analysis is investigated to consider
simultaneously the interaction between technical, economic, and environmental aspects of the system. Accordingly,
there is an optimum value for the isentropic efficiency of the C-1 compressor that should be examined, and the
more/fewer is its pressure ratio, the more/fewer are its exergy costs and/or environmental impacts. Moreover, whilst
an optimum pressure ratio should be found out for EXP-2 expander, a higher isentropic efficiency definitely decreases
its exergy cost and environmental impact. In addition, the less/more is the temperature approach Tmin of
HX-1 heat exchanger, the less/more are its exergy costs and/or its environmental impacts. As well as, its input
pressure should be maximized to achieve minimum exergy costs and environmental impacts of the component.
Finally, tower pressure should be raised as much as possible to achieve the least exergy costs and environmental
impacts of the T-101 generator. However, its inlet temperature has an optimum value that should be found out.
process. The proposed process is a simple Claude cycle combined with two absorption refrigeration systems (ARSs).
The mass flow rate of the liquid hydrogen (LH2) production is about 260 tones per day and the specific energy
consumption (SEC) and the exergy efficiency of the system are12.7 kWh/kgLH2 and 31.6% respectively. The results
show that the HX-201 and HX-203 heat exchangers have the highest total environmental impact and total exergy
cost. Therefore, they are in the priority of improving to achieve better performance for overall the process. In
addition, the P-101 pump has the highest exergoeconomic and exergoenvairomental coefficient. Therefore, its capital
investment cost and its environmental impact should be reduced to decrease the cost and environmental impact
of the whole system. Furthermore, the HX-201 heat exchanger has the lowest exergoeconomic and exergoenvairomental
coefficient. Therefore, the technical performance of this device should be improved to reduce the
cost and environmental impact of the whole system. In addition, a 3D sensitivity analysis is investigated to consider
simultaneously the interaction between technical, economic, and environmental aspects of the system. Accordingly,
there is an optimum value for the isentropic efficiency of the C-1 compressor that should be examined, and the
more/fewer is its pressure ratio, the more/fewer are its exergy costs and/or environmental impacts. Moreover, whilst
an optimum pressure ratio should be found out for EXP-2 expander, a higher isentropic efficiency definitely decreases
its exergy cost and environmental impact. In addition, the less/more is the temperature approach Tmin of
HX-1 heat exchanger, the less/more are its exergy costs and/or its environmental impacts. As well as, its input
pressure should be maximized to achieve minimum exergy costs and environmental impacts of the component.
Finally, tower pressure should be raised as much as possible to achieve the least exergy costs and environmental
impacts of the T-101 generator. However, its inlet temperature has an optimum value that should be found out.