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Gulshan Sachdeva - One of the best experts on this subject based on the ideXlab platform.
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Performance analysis of a vapour compression-absorption cascaded refrigeration system with undersized evaporator and condenser
Journal of Energy in Southern Africa, 2017Co-Authors: Vaibhav Jain, Gulshan Sachdeva, Surendra Singh KachhwahaAbstract:In a present study, the performance of a vapour compression–absorption cascaded refrigeration system (CRS) under fouled conditions was analysed. The main effect of fouling is to decrease the effectiveness of the heat exchanger. Thus, the overall conductance (UA) of the heat exchanger is decreased. Hence, another interpretation of fouling is to reduce the effective size of the heat exchanger. In the present work, the percentage decrease in the overall conductance value (UA) of evaporator and condenser due to their fouling is varied from 0 to 50% and its consequences on various aspects of CRS are generated to ascertain any possible patterns. The detailed first law analysis reveals that for a clean evaporator and condenser, the electricity consumption is 67.5% less than vapour compression system (VCS) for the same cooling capacity. CRS is able to save only 61.3% of electrical energy when evaporator and condenser conductance is reduced by 50% due to fouling. Evaporator and condenser fouling decreased the COP and Rational Efficiency of the system by 4.7% and 10.5% respectively. It is also important to note that irreversibility in the evaporator and condenser is increased by 42.4% and 62.1% respectively, when their individual performance is degraded by 50% due to fouling.
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comparative performance study of vapour compression absorption cascaded system at optimum condensing temperature
International Journal of Energy Technology and Policy, 2016Co-Authors: Vaibhav Jain, Gulshan Sachdeva, Surendra Singh KachhwahaAbstract:The present study thermodynamically analyse a vapour compression-absorption cascaded refrigeration system (CRS) that uses R407C and H2O-LiBr as refrigerants, to determine the optimal condensing temperature of cascade condenser. The optimum condensing temperature of cascade condenser is found to be 18°C for 83.09 kW refrigeration capacity at an evaporating and condensing temperature of 0.4°C and 46.8°C respectively. The optimum condensing temperature is found, to maximise the Rational Efficiency of CRS and minimise the total irreversibility of system. Further comparative study of CRS with equivalent vapour compression refrigeration system (VCRS) used for water chilling applications shows that the electric power consumption in CRS is reduced by 70% and COP of compression section is improved by 235% as compared to equivalent VCRS.
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Thermodynamic modelling and parametric study of a low temperature vapour compression-absorption system based on modified Gouy-Stodola equation
Energy, 2015Co-Authors: Vaibhav Jain, Gulshan Sachdeva, Surendra Singh KachhwahaAbstract:Present paper thermodynamically analyses a VCAS (vapour compression-absorption system) with carbon dioxide (compression section) and ammonia-water (absorption section) as refrigerants and determines the optimal condensing temperature of cascade condenser using modified Gouy-Stodola equation. The optimum cascade condenser temperature is found to be −13 °C for 175 kW refrigeration capacity at an evaporator temperature of −45 °C and condenser temperature of 35 °C. The optimum cascade condenser temperature maximises the overall COP, Rational Efficiency and minimises the total irreversibility rate of the VCAS system. The value of optimum condensing temperature and its corresponding maximum COP, and minimum irreversibility rate are discussed for a wide range of operating conditions. Further, a comparative study of TSVCS (two stage vapour compression system) used for low temperature refrigeration applications with VCAS shows that at design point, primary energy consumption is reduced by 60.6% and electrical COP is improved by 153.6% in VCAS as compared to conventional TSVCS. But the total irreversibility rate of VCAS is 38.4% higher than the TSVCS due to the use of low grade energy in vapour absorption system and hence the Rational Efficiency of VCAS is 14% low.
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thermodynamic performance analysis of a vapor compression absorption cascaded refrigeration system
Energy Conversion and Management, 2013Co-Authors: Vaibhav Jain, Surendra Singh Kachhwaha, Gulshan SachdevaAbstract:Abstract In the present study, a thermodynamic model for cascaded vapor compression–absorption system (CVCAS) has been developed which consists of a vapor compression refrigeration system (VCRS) coupled with single effect vapor absorption refrigeration system (VARS). Based on first and second laws, a comparative performance analysis of CVCAS and an independent VCRS has been carried out for a design capacity of 66.67 kW. The results show that the electric power consumption in CVCAS is reduced by 61% and COP of compression section is improved by 155% with respect to the corresponding values pertaining to a conventional VCRS. However there is a trade-off between these parameters and the Rational Efficiency which is found to decrease to half of that for a VCRS. The effect of various operating parameters, i.e., superheating, subcooling, cooling capacity, inlet temperature and the product of effectiveness and heat capacitance of external fluids are extensively studied on the COP, total irreversibility and Rational Efficiency of the CVCAS. Besides, the performance of environment friendly refrigerants such as R410A, R407C and R134A is found to be almost at par with that of R22. Hence, all the alternative refrigerants selected herein can serve as potential substitutes for R22. Furthermore, it has been found that reducing the irreversibility rate of the condenser by one unit due to decrease in condenser temperature depicted approximately 3.8 times greater reduction in the total irreversibility rate of the CVCAS, whereas unit reduction in the evaporator’s irreversibility rate due to increase in evaporator temperature reduced total irreversibility rate by 3.4 times for the same system. Since the changes in the inlet temperatures of external fluid in the condenser and the evaporator contribute significant changes in system’s overall irreversibility, due consideration is required in condenser and evaporator temperatures to improve the system performance.
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Thermodynamic performance analysis of a vapor compression–absorption cascaded refrigeration system
Energy Conversion and Management, 2013Co-Authors: Vaibhav Jain, Surendra Singh Kachhwaha, Gulshan SachdevaAbstract:Abstract In the present study, a thermodynamic model for cascaded vapor compression–absorption system (CVCAS) has been developed which consists of a vapor compression refrigeration system (VCRS) coupled with single effect vapor absorption refrigeration system (VARS). Based on first and second laws, a comparative performance analysis of CVCAS and an independent VCRS has been carried out for a design capacity of 66.67 kW. The results show that the electric power consumption in CVCAS is reduced by 61% and COP of compression section is improved by 155% with respect to the corresponding values pertaining to a conventional VCRS. However there is a trade-off between these parameters and the Rational Efficiency which is found to decrease to half of that for a VCRS. The effect of various operating parameters, i.e., superheating, subcooling, cooling capacity, inlet temperature and the product of effectiveness and heat capacitance of external fluids are extensively studied on the COP, total irreversibility and Rational Efficiency of the CVCAS. Besides, the performance of environment friendly refrigerants such as R410A, R407C and R134A is found to be almost at par with that of R22. Hence, all the alternative refrigerants selected herein can serve as potential substitutes for R22. Furthermore, it has been found that reducing the irreversibility rate of the condenser by one unit due to decrease in condenser temperature depicted approximately 3.8 times greater reduction in the total irreversibility rate of the CVCAS, whereas unit reduction in the evaporator’s irreversibility rate due to increase in evaporator temperature reduced total irreversibility rate by 3.4 times for the same system. Since the changes in the inlet temperatures of external fluid in the condenser and the evaporator contribute significant changes in system’s overall irreversibility, due consideration is required in condenser and evaporator temperatures to improve the system performance.
Vaibhav Jain - One of the best experts on this subject based on the ideXlab platform.
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Performance analysis of a vapour compression-absorption cascaded refrigeration system with undersized evaporator and condenser
Journal of Energy in Southern Africa, 2017Co-Authors: Vaibhav Jain, Gulshan Sachdeva, Surendra Singh KachhwahaAbstract:In a present study, the performance of a vapour compression–absorption cascaded refrigeration system (CRS) under fouled conditions was analysed. The main effect of fouling is to decrease the effectiveness of the heat exchanger. Thus, the overall conductance (UA) of the heat exchanger is decreased. Hence, another interpretation of fouling is to reduce the effective size of the heat exchanger. In the present work, the percentage decrease in the overall conductance value (UA) of evaporator and condenser due to their fouling is varied from 0 to 50% and its consequences on various aspects of CRS are generated to ascertain any possible patterns. The detailed first law analysis reveals that for a clean evaporator and condenser, the electricity consumption is 67.5% less than vapour compression system (VCS) for the same cooling capacity. CRS is able to save only 61.3% of electrical energy when evaporator and condenser conductance is reduced by 50% due to fouling. Evaporator and condenser fouling decreased the COP and Rational Efficiency of the system by 4.7% and 10.5% respectively. It is also important to note that irreversibility in the evaporator and condenser is increased by 42.4% and 62.1% respectively, when their individual performance is degraded by 50% due to fouling.
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comparative performance study of vapour compression absorption cascaded system at optimum condensing temperature
International Journal of Energy Technology and Policy, 2016Co-Authors: Vaibhav Jain, Gulshan Sachdeva, Surendra Singh KachhwahaAbstract:The present study thermodynamically analyse a vapour compression-absorption cascaded refrigeration system (CRS) that uses R407C and H2O-LiBr as refrigerants, to determine the optimal condensing temperature of cascade condenser. The optimum condensing temperature of cascade condenser is found to be 18°C for 83.09 kW refrigeration capacity at an evaporating and condensing temperature of 0.4°C and 46.8°C respectively. The optimum condensing temperature is found, to maximise the Rational Efficiency of CRS and minimise the total irreversibility of system. Further comparative study of CRS with equivalent vapour compression refrigeration system (VCRS) used for water chilling applications shows that the electric power consumption in CRS is reduced by 70% and COP of compression section is improved by 235% as compared to equivalent VCRS.
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Thermodynamic modelling and parametric study of a low temperature vapour compression-absorption system based on modified Gouy-Stodola equation
Energy, 2015Co-Authors: Vaibhav Jain, Gulshan Sachdeva, Surendra Singh KachhwahaAbstract:Present paper thermodynamically analyses a VCAS (vapour compression-absorption system) with carbon dioxide (compression section) and ammonia-water (absorption section) as refrigerants and determines the optimal condensing temperature of cascade condenser using modified Gouy-Stodola equation. The optimum cascade condenser temperature is found to be −13 °C for 175 kW refrigeration capacity at an evaporator temperature of −45 °C and condenser temperature of 35 °C. The optimum cascade condenser temperature maximises the overall COP, Rational Efficiency and minimises the total irreversibility rate of the VCAS system. The value of optimum condensing temperature and its corresponding maximum COP, and minimum irreversibility rate are discussed for a wide range of operating conditions. Further, a comparative study of TSVCS (two stage vapour compression system) used for low temperature refrigeration applications with VCAS shows that at design point, primary energy consumption is reduced by 60.6% and electrical COP is improved by 153.6% in VCAS as compared to conventional TSVCS. But the total irreversibility rate of VCAS is 38.4% higher than the TSVCS due to the use of low grade energy in vapour absorption system and hence the Rational Efficiency of VCAS is 14% low.
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thermodynamic performance analysis of a vapor compression absorption cascaded refrigeration system
Energy Conversion and Management, 2013Co-Authors: Vaibhav Jain, Surendra Singh Kachhwaha, Gulshan SachdevaAbstract:Abstract In the present study, a thermodynamic model for cascaded vapor compression–absorption system (CVCAS) has been developed which consists of a vapor compression refrigeration system (VCRS) coupled with single effect vapor absorption refrigeration system (VARS). Based on first and second laws, a comparative performance analysis of CVCAS and an independent VCRS has been carried out for a design capacity of 66.67 kW. The results show that the electric power consumption in CVCAS is reduced by 61% and COP of compression section is improved by 155% with respect to the corresponding values pertaining to a conventional VCRS. However there is a trade-off between these parameters and the Rational Efficiency which is found to decrease to half of that for a VCRS. The effect of various operating parameters, i.e., superheating, subcooling, cooling capacity, inlet temperature and the product of effectiveness and heat capacitance of external fluids are extensively studied on the COP, total irreversibility and Rational Efficiency of the CVCAS. Besides, the performance of environment friendly refrigerants such as R410A, R407C and R134A is found to be almost at par with that of R22. Hence, all the alternative refrigerants selected herein can serve as potential substitutes for R22. Furthermore, it has been found that reducing the irreversibility rate of the condenser by one unit due to decrease in condenser temperature depicted approximately 3.8 times greater reduction in the total irreversibility rate of the CVCAS, whereas unit reduction in the evaporator’s irreversibility rate due to increase in evaporator temperature reduced total irreversibility rate by 3.4 times for the same system. Since the changes in the inlet temperatures of external fluid in the condenser and the evaporator contribute significant changes in system’s overall irreversibility, due consideration is required in condenser and evaporator temperatures to improve the system performance.
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Thermodynamic performance analysis of a vapor compression–absorption cascaded refrigeration system
Energy Conversion and Management, 2013Co-Authors: Vaibhav Jain, Surendra Singh Kachhwaha, Gulshan SachdevaAbstract:Abstract In the present study, a thermodynamic model for cascaded vapor compression–absorption system (CVCAS) has been developed which consists of a vapor compression refrigeration system (VCRS) coupled with single effect vapor absorption refrigeration system (VARS). Based on first and second laws, a comparative performance analysis of CVCAS and an independent VCRS has been carried out for a design capacity of 66.67 kW. The results show that the electric power consumption in CVCAS is reduced by 61% and COP of compression section is improved by 155% with respect to the corresponding values pertaining to a conventional VCRS. However there is a trade-off between these parameters and the Rational Efficiency which is found to decrease to half of that for a VCRS. The effect of various operating parameters, i.e., superheating, subcooling, cooling capacity, inlet temperature and the product of effectiveness and heat capacitance of external fluids are extensively studied on the COP, total irreversibility and Rational Efficiency of the CVCAS. Besides, the performance of environment friendly refrigerants such as R410A, R407C and R134A is found to be almost at par with that of R22. Hence, all the alternative refrigerants selected herein can serve as potential substitutes for R22. Furthermore, it has been found that reducing the irreversibility rate of the condenser by one unit due to decrease in condenser temperature depicted approximately 3.8 times greater reduction in the total irreversibility rate of the CVCAS, whereas unit reduction in the evaporator’s irreversibility rate due to increase in evaporator temperature reduced total irreversibility rate by 3.4 times for the same system. Since the changes in the inlet temperatures of external fluid in the condenser and the evaporator contribute significant changes in system’s overall irreversibility, due consideration is required in condenser and evaporator temperatures to improve the system performance.
Surendra Singh Kachhwaha - One of the best experts on this subject based on the ideXlab platform.
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Performance analysis of a vapour compression-absorption cascaded refrigeration system with undersized evaporator and condenser
Journal of Energy in Southern Africa, 2017Co-Authors: Vaibhav Jain, Gulshan Sachdeva, Surendra Singh KachhwahaAbstract:In a present study, the performance of a vapour compression–absorption cascaded refrigeration system (CRS) under fouled conditions was analysed. The main effect of fouling is to decrease the effectiveness of the heat exchanger. Thus, the overall conductance (UA) of the heat exchanger is decreased. Hence, another interpretation of fouling is to reduce the effective size of the heat exchanger. In the present work, the percentage decrease in the overall conductance value (UA) of evaporator and condenser due to their fouling is varied from 0 to 50% and its consequences on various aspects of CRS are generated to ascertain any possible patterns. The detailed first law analysis reveals that for a clean evaporator and condenser, the electricity consumption is 67.5% less than vapour compression system (VCS) for the same cooling capacity. CRS is able to save only 61.3% of electrical energy when evaporator and condenser conductance is reduced by 50% due to fouling. Evaporator and condenser fouling decreased the COP and Rational Efficiency of the system by 4.7% and 10.5% respectively. It is also important to note that irreversibility in the evaporator and condenser is increased by 42.4% and 62.1% respectively, when their individual performance is degraded by 50% due to fouling.
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comparative performance study of vapour compression absorption cascaded system at optimum condensing temperature
International Journal of Energy Technology and Policy, 2016Co-Authors: Vaibhav Jain, Gulshan Sachdeva, Surendra Singh KachhwahaAbstract:The present study thermodynamically analyse a vapour compression-absorption cascaded refrigeration system (CRS) that uses R407C and H2O-LiBr as refrigerants, to determine the optimal condensing temperature of cascade condenser. The optimum condensing temperature of cascade condenser is found to be 18°C for 83.09 kW refrigeration capacity at an evaporating and condensing temperature of 0.4°C and 46.8°C respectively. The optimum condensing temperature is found, to maximise the Rational Efficiency of CRS and minimise the total irreversibility of system. Further comparative study of CRS with equivalent vapour compression refrigeration system (VCRS) used for water chilling applications shows that the electric power consumption in CRS is reduced by 70% and COP of compression section is improved by 235% as compared to equivalent VCRS.
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Thermodynamic modelling and parametric study of a low temperature vapour compression-absorption system based on modified Gouy-Stodola equation
Energy, 2015Co-Authors: Vaibhav Jain, Gulshan Sachdeva, Surendra Singh KachhwahaAbstract:Present paper thermodynamically analyses a VCAS (vapour compression-absorption system) with carbon dioxide (compression section) and ammonia-water (absorption section) as refrigerants and determines the optimal condensing temperature of cascade condenser using modified Gouy-Stodola equation. The optimum cascade condenser temperature is found to be −13 °C for 175 kW refrigeration capacity at an evaporator temperature of −45 °C and condenser temperature of 35 °C. The optimum cascade condenser temperature maximises the overall COP, Rational Efficiency and minimises the total irreversibility rate of the VCAS system. The value of optimum condensing temperature and its corresponding maximum COP, and minimum irreversibility rate are discussed for a wide range of operating conditions. Further, a comparative study of TSVCS (two stage vapour compression system) used for low temperature refrigeration applications with VCAS shows that at design point, primary energy consumption is reduced by 60.6% and electrical COP is improved by 153.6% in VCAS as compared to conventional TSVCS. But the total irreversibility rate of VCAS is 38.4% higher than the TSVCS due to the use of low grade energy in vapour absorption system and hence the Rational Efficiency of VCAS is 14% low.
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thermodynamic performance analysis of a vapor compression absorption cascaded refrigeration system
Energy Conversion and Management, 2013Co-Authors: Vaibhav Jain, Surendra Singh Kachhwaha, Gulshan SachdevaAbstract:Abstract In the present study, a thermodynamic model for cascaded vapor compression–absorption system (CVCAS) has been developed which consists of a vapor compression refrigeration system (VCRS) coupled with single effect vapor absorption refrigeration system (VARS). Based on first and second laws, a comparative performance analysis of CVCAS and an independent VCRS has been carried out for a design capacity of 66.67 kW. The results show that the electric power consumption in CVCAS is reduced by 61% and COP of compression section is improved by 155% with respect to the corresponding values pertaining to a conventional VCRS. However there is a trade-off between these parameters and the Rational Efficiency which is found to decrease to half of that for a VCRS. The effect of various operating parameters, i.e., superheating, subcooling, cooling capacity, inlet temperature and the product of effectiveness and heat capacitance of external fluids are extensively studied on the COP, total irreversibility and Rational Efficiency of the CVCAS. Besides, the performance of environment friendly refrigerants such as R410A, R407C and R134A is found to be almost at par with that of R22. Hence, all the alternative refrigerants selected herein can serve as potential substitutes for R22. Furthermore, it has been found that reducing the irreversibility rate of the condenser by one unit due to decrease in condenser temperature depicted approximately 3.8 times greater reduction in the total irreversibility rate of the CVCAS, whereas unit reduction in the evaporator’s irreversibility rate due to increase in evaporator temperature reduced total irreversibility rate by 3.4 times for the same system. Since the changes in the inlet temperatures of external fluid in the condenser and the evaporator contribute significant changes in system’s overall irreversibility, due consideration is required in condenser and evaporator temperatures to improve the system performance.
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Thermodynamic performance analysis of a vapor compression–absorption cascaded refrigeration system
Energy Conversion and Management, 2013Co-Authors: Vaibhav Jain, Surendra Singh Kachhwaha, Gulshan SachdevaAbstract:Abstract In the present study, a thermodynamic model for cascaded vapor compression–absorption system (CVCAS) has been developed which consists of a vapor compression refrigeration system (VCRS) coupled with single effect vapor absorption refrigeration system (VARS). Based on first and second laws, a comparative performance analysis of CVCAS and an independent VCRS has been carried out for a design capacity of 66.67 kW. The results show that the electric power consumption in CVCAS is reduced by 61% and COP of compression section is improved by 155% with respect to the corresponding values pertaining to a conventional VCRS. However there is a trade-off between these parameters and the Rational Efficiency which is found to decrease to half of that for a VCRS. The effect of various operating parameters, i.e., superheating, subcooling, cooling capacity, inlet temperature and the product of effectiveness and heat capacitance of external fluids are extensively studied on the COP, total irreversibility and Rational Efficiency of the CVCAS. Besides, the performance of environment friendly refrigerants such as R410A, R407C and R134A is found to be almost at par with that of R22. Hence, all the alternative refrigerants selected herein can serve as potential substitutes for R22. Furthermore, it has been found that reducing the irreversibility rate of the condenser by one unit due to decrease in condenser temperature depicted approximately 3.8 times greater reduction in the total irreversibility rate of the CVCAS, whereas unit reduction in the evaporator’s irreversibility rate due to increase in evaporator temperature reduced total irreversibility rate by 3.4 times for the same system. Since the changes in the inlet temperatures of external fluid in the condenser and the evaporator contribute significant changes in system’s overall irreversibility, due consideration is required in condenser and evaporator temperatures to improve the system performance.
Olav Olland - One of the best experts on this subject based on the ideXlab platform.
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optimized process configurations of post combustion co2 capture for natural gas fired power plant power plant Efficiency analysis
International Journal of Greenhouse Gas Control, 2012Co-Authors: Zeinab Amrollahi, Paul Andreas Marchioro Ystad, Iva S Ertesvag, Olav OllandAbstract:This thesis work presents an evaluation of various processes for reducing CO2 emissions from natural-gas-fired combined cycle (NGCC) power plants. The scope of the thesis is to focus mainly on post-combustion chemical absorption for NGCC. For the post-combustion capture plant, an important interface is the steam extraction from the steam turbine in order to supply the heat for solvent regeneration. The steam extraction imposes a power production penalty. The thesis includes analysis and comparison between several chemical absorption processes configurations integrated with NGCC.The objectives of the present work were to use thermodynamic analysis on various chemical absorption process configurations to evaluate, quantify and justify improved design of NGCC with post-combustion CO2 capture. The thermodynamic evaluation of the processes gave insight to the detailed distribution of process irreversibilities and supports the state-of-the-art process configuration with the lowest energy penalty due to addition of CO2 capture to the power plant.The reference power plant without CO2 capture has a power production of 384 MW and a net electric Efficiency of 56.4% (LHV) with CO2 emissions of ≈ 362 g CO2/ net kWh electricity. The power plant design was carried out using the computational tool GTPRO. The aim of the CO2 capture plant was to remove 90% of the CO2 emissions present in the flue gas. To assess and analyse the various chemical absorption process configurations, the UniSim Design software was used, which contains the Amines Property Package. This special property package has been designed to aid the modelling of alkanolamine treating units in which CO2 is removed from gaseous streams. The downstream compression of the captured CO2 was also simulated using UniSim Design.The investigated process configurations were comprised of chemical absorption process with absorber inter-cooling, split-flow process and lean vapour recompression (LVR) process. Several design parameters were modified for each of the process configurations to achieve low energy consumption and consequently low work demand. The inter-cooling of the absorber column led to increased solvent rich loading. Consequently, the solvent circulation rate and reboiler energy requirement was decreased. In the split-flow configuration, due to splitting of the rich solvent into two streams, the amount of rich solvent entering the bottom section of the stripper was reduced. Therefore, less reboiler energy was required to remove CO2 from the solvent to reach the same solvent lean loading as of the reference chemical absorption process. In the configuration with lean vapour recompression (LVR), the lean solvent stream was utilised as a low temperature heat source in order to add exergy input in the form of steam to the stripper column and thus reduce the reboiler duty. The reboiler duty for the CO2 capture was decreased from 3.74 MJ/kgCO2 in the reference chemical absorption process to 2.71 MJ/kgCO2 for the case of LVR with absorber inter-cooling. The net electric Efficiency of the reference process with CO2 capture was calculated to 49.5% (LHV). With the improved process design, the highest net power plant Efficiency was calculated to 50.2 % (LHV) for the case of LVR with absorber inter-cooling.Moreover, exergy analysis was performed to identify the irreversibilities associated with the integration of power plant with various CO2 capture and compression processes. Particularly, the second law of thermodynamics was used as a tool to evaluate and quantify the reduction of energy penalty associated with CO2 capture for each process modification. Defining the work input for a theoretical reversible CO2 capture process as the minimum required work was functional step in characterising the difference of the work input of theoretical reversible processes and the real irreversible processes. Exergy Efficiency of the reference chemical absorption process was calculated to 21.3 % versus 25 % for the case of LVR with absorber inter-cooling. Through exergy balance for every CO2 capture process configuration, the exchange of exergy content of material and energy streams was assessed.Using the combination of power plant Efficiency and exergy analysis as tools, a pre-combustion reforming combined cycle (IRCC) process with chemical absorption CO2 capture process was investigated. A Rational Efficiency of 43.8% was achieved, which indicates the share of input exergy utilised for work production by the power cycle in addition to the exergy of the pure compressed CO2 stream. The highest amount of irreversibility was contributed by the gas turbine and mainly by the combustor. The irreversibility which is inherent in the combustion process corresponded to a large fraction of original exergy of the fuel. This could be partially compensated by increase the preheating of the fuel supplied to the combustor. Also preheating the inlet streams to auto-thermal reactor (ATR) was found advantageous in decreasing the ATR irreversibilities.
Rabah Gomri - One of the best experts on this subject based on the ideXlab platform.
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second law comparison of single effect and double effect vapour absorption refrigeration systems
Energy Conversion and Management, 2009Co-Authors: Rabah GomriAbstract:Abstract In this paper a comparative study between single effect and double effect absorption refrigeration systems with identical cold output is carried out. Simulation results were used to study the influence of the various operating parameters on the performance coefficient, the thermal loads of the components, exergetic Efficiency (Rational Efficiency) and the total change in exergy of the two systems. It is concluded that the COP of double effect system is approximately twice the COP of single effect system but the exergetic Efficiency of double effect system increase slightly compared to the exergetic Efficiency of single effect system. It is found that for each condenser and evaporator temperature, there is an optimum generator temperature where the total change in exergy of the single effect and double effect absorption refrigeration systems is minimum. At this point the COP and exergetic Efficiency of the systems become maximum. In this study and when the evaporation temperature is varied from 4 °C to 10 °C, condenser and absorber temperatures are varied from 33 °C to 39 °C and generator (HPG) temperature is varied from 60 °C to 190 °C the maximum COP values of the single effect refrigeration systems are in the range of 0.73–0.79 and for double effect refrigeration systems are in the range of 1.22–1.42. The maximum exergetic Efficiency values of the single effect refrigeration systems are in the range of 12.5–23.2% and for double effect refrigeration systems are in the range of 14.3–25.1%.
