8 results on '"Inter-stage pressure"'
Search Results
2. Thermodynamic analysis and optimization of a novel two-stage transcritical N2O cycle
- Author
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Agrawal, Neeraj, Sarkar, Jahar, and Bhattacharyya, Souvik
- Subjects
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THERMODYNAMICS , *MATHEMATICAL optimization , *NITROUS oxide , *FORCE & energy , *COMPRESSORS , *SIMULATION methods & models , *TEMPERATURE effect - Abstract
Abstract: Thermodynamic (energy and exergy) analyses and optimization studies of two-stage transcritical N2O and CO2 cycles, incorporating compressor intercooling, are presented based on cycle simulation employing simultaneous optimization of intercooler pressure and gas cooler pressure. Further, performance comparisons with the basic single-stage cycles are also presented. The N2O cycle exhibits higher cooling COP, lower optimum gas cooler pressure and discharge temperature and higher second law efficiency as compared to an equivalent CO2 cycle. However, two-stage compression with intercooling yields lesser COP improvement for N2O compared to CO2. Based on the cycle simulations, correlations of optimum gas cooler pressure and inter-stage pressure in terms of gas cooler exit temperature and evaporator temperature are obtained. This is expected to be of help as a guideline in optimal design and operation of such systems. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
3. Second law analysis of two-stage compression transcritical CO2 heat pump cycle.
- Author
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Özgür, Arif Emre and Bayrakçi, Hilmi Cenk
- Subjects
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ENVIRONMENTAL law , *INDUSTRIAL laws & legislation , *TRAFFIC regulations , *PERFORMANCE (Law) , *DISCHARGE of contracts , *CONSTRUCTION laws , *ZONING law , *GLOBAL temperature changes , *HEATING & ventilation industry - Abstract
Because of the global warming impact of hydro fluorocarbons, the uses of natural refrigerants in automotive and HVAC industries have received worldwide attention. CO2 is the most promising refrigerant in these industries, especially the transcritical CO2 refrigeration cycle. The objective of this work is to identify the main factors that affect two-stage compression transcritical CO2 system efficiency. A second law of thermodynamic analysis on the entire two-stage CO2 cycle is conducted so that the exergy destruction of each system component can be deduced and ranked, allowing future efforts to focus on improving the components that have the highest potential for advancement. The inter-stage pressure is used as a variable parameter in the analysis study. The second law efficiency, coefficient of cooling performance and total exergy destruction of the system variations with the inter-stage pressure are presented graphically. It was concluded that there is an optimum inter-stage pressure that maximizes both first law and second law efficiencies. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
4. Optimization of two-stage transcritical carbon dioxide heat pump cycles
- Author
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Agrawal, Neeraj, Bhattacharyya, Souvik, and Sarkar, J.
- Subjects
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CARBON dioxide , *HEAT transfer , *HEAT exchangers , *PUMPING machinery - Abstract
Abstract: Optimization studies of two-stage transcritical carbon dioxide heat pump cycles, incorporating options such as flash gas bypass, flash intercooling and compressor intercooling, are presented based on cycle simulation. Sub-critical and super-critical thermodynamic and transport properties of carbon dioxide coded and then integrated with the simulation code for further analyses. Results exhibit improvement in performance by adopting optimal operating conditions. The optimum interstage pressure, thus obtained, deviate from the classical estimate of geometric mean of gas cooler and evaporator pressure. It is observed that the flash gas bypass system yields the best performance among the three two stage cycles analyzed. Internal heat exchanger effectiveness and compressor isentropic efficiency shows marginal influence on the system performance. Internal heat exchanger effectiveness shows marginal influence on the system performance while compressor isentropic efficiency shows an about 10% variation in COP. However, optimum gas cooler pressure and optimum intermediate pressure are only marginally affected. Based on the cycle simulations, correlations of optimum gas cooler pressure and inter-stage pressure in terms of gas cooler temperature and evaporator temperature are obtained. This would be useful as a guideline in design of such systems. [Copyright &y& Elsevier]
- Published
- 2007
- Full Text
- View/download PDF
5. A general methodology for energy comparison of intermediate configurations in two-stage vapour compression refrigeration systems
- Author
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E. Torrella, J.A. Larumbe, Daniel Sánchez, Rodrigo Llopis, and Ramón Cabello
- Subjects
Engineering ,Refrigeració ,Inter-stage pressure ,Mechanical engineering ,Industrial and Manufacturing Engineering ,Domain (software engineering) ,Refrigeration and refrigerating machinery ,Electrical and Electronic Engineering ,Civil and Structural Engineering ,business.industry ,Vapour compression ,Mechanical Engineering ,Heat pump and refrigeration cycle ,Refrigeration ,Two-stage refrigerating cycle ,Building and Construction ,Compression (physics) ,Pollution ,Subcooling ,General Energy ,MAQUINAS Y MOTORES TERMICOS ,Vapor tecnologia ,Stage (hydrology) ,business ,Energy (signal processing) - Abstract
The aim of the present paper is to describe a general methodology suitable for analysing any intermediate configuration considered in staged vapour compression refrigeration cycles. This general methodology only depends on two basic parameters related to the subcooling and desuperheating obtained in the inter-stage system. A COP expression based on the two basic parameters was obtained from the general configuration. By means of its particularization to seven common configurations, it was then possible to make an energy comparison of the various configurations working with two fluids appropriated for the low temperature domain such as ammonia and R-404A., The authors are indebted to the Spanish Ministry of Education and Science (CTM2008-06468-C02-02/TECNO) and to the Spanish Ministry of the Environment and Rural and Marine Affairs (200800050084716) for their economic support to this work.
- Published
- 2011
6. A general methodology for energy comparison of intermediate configurations in two-stage vapour compression refrigeration systems
- Author
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Universitat Politècnica de València. Departamento de Termodinámica Aplicada - Departament de Termodinàmica Aplicada, Ministerio de Medio Ambiente y Medio Rural y Marino, Ministerio de Ciencia e Innovación, Torrella Alcaraz, Enrique, Larumbe Bernad, Juan Antonio, Cabello, R., Llopis, R., Sanchez, D., Universitat Politècnica de València. Departamento de Termodinámica Aplicada - Departament de Termodinàmica Aplicada, Ministerio de Medio Ambiente y Medio Rural y Marino, Ministerio de Ciencia e Innovación, Torrella Alcaraz, Enrique, Larumbe Bernad, Juan Antonio, Cabello, R., Llopis, R., and Sanchez, D.
- Abstract
The aim of the present paper is to describe a general methodology suitable for analysing any intermediate configuration considered in staged vapour compression refrigeration cycles. This general methodology only depends on two basic parameters related to the subcooling and desuperheating obtained in the inter-stage system. A COP expression based on the two basic parameters was obtained from the general configuration. By means of its particularization to seven common configurations, it was then possible to make an energy comparison of the various configurations working with two fluids appropriated for the low temperature domain such as ammonia and R-404A.
- Published
- 2011
7. Second law analysis of two-stage vapour compression refrigeration plants
- Author
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Ministerio de Educación y Ciencia, Ministerio de Medio Ambiente y Medio Rural y Marino, Torrella Alcaraz, Enrique, Llopis, R., Cabello, R., Sanchez, D., Larumbe, J.A., Ministerio de Educación y Ciencia, Ministerio de Medio Ambiente y Medio Rural y Marino, Torrella Alcaraz, Enrique, Llopis, R., Cabello, R., Sanchez, D., and Larumbe, J.A.
- Abstract
[EN] This paper describes a Second Law Analysis based on experimental data of a two-stage vapour compression facility driven by a compound compressor for medium and low-capacity refrigeration applications, which operates with the most usual inter-stage configurations (direct liquid injection and subcooler). The experimental analysis is performed for an evaporating temperature range between 36 degrees C and 20 degrees C and for a condensing temperature range between 30 degrees C and 47 degrees C using the refrigerant R-404A. The final results are compared with energy analysis from previous works. Additionally, a new criterion of equivalence between the simple vapour compression cycle and the two-stage compression cycle is given.
- Published
- 2010
8. Second-law analysis of two-stage vapour compression refrigeration plants
- Author
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J.A. Larumbe, Ramón Cabello, E. Torrella, Daniel Sánchez, and Rodrigo Llopis
- Subjects
Exergy ,Materials science ,Refrigeració ,Vapour compression ,Inter-stage pressure ,Second law analysis ,Refrigeration ,Thermodynamics ,Two-stage refrigerating cycle ,Mechanics ,Atmospheric temperature range ,Compression (physics) ,Refrigerant ,Exergy analysis ,General Energy ,MAQUINAS Y MOTORES TERMICOS ,R-404A ,Stage (hydrology) ,Cooling ,Gas compressor - Abstract
[EN] This paper describes a Second Law Analysis based on experimental data of a two-stage vapour compression facility driven by a compound compressor for medium and low-capacity refrigeration applications, which operates with the most usual inter-stage configurations (direct liquid injection and subcooler). The experimental analysis is performed for an evaporating temperature range between 36 degrees C and 20 degrees C and for a condensing temperature range between 30 degrees C and 47 degrees C using the refrigerant R-404A. The final results are compared with energy analysis from previous works. Additionally, a new criterion of equivalence between the simple vapour compression cycle and the two-stage compression cycle is given., The authors are indebted to the Spanish Ministry of Education and Science (CTM2008-06468-C02-02/TECNO) and to the Spanish Ministry of the Environment and Rural and Marine Affairs (200800050084716) for their economic support to this work.
- Published
- 2010
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