The Experts below are selected from a list of 96723 Experts worldwide ranked by ideXlab platform
Jia Yan - One of the best experts on this subject based on the ideXlab platform.
-
analysis on performance characteristics of ejector with variable area ratio for multi evaporator refrigeration system based on experimental data
Applied Thermal Engineering, 2014Co-Authors: Wenjian Cai, Haoran Chen, Jia YanAbstract:Abstract This paper presents a study on experiment and analysis of variable area-ratio ejector used in a multi-evaporator refrigeration system (MERS). The experimental rig and method are described, and the entrainment and Pressure Recovery performances of the variable ejector are measured at various operating and geometric conditions. The critical area ratio is proposed as an indicator of Pressure Recovery status; area ratios smaller than the critical ones are required to make sure that the system operates at energy saving mode. The investigation results indicate that the entrainment ratio, Pressure Recovery ratio and critical area ratio are strongly affected by the primary Pressure and secondary Pressure. Greater entrainment ratio can be obtained by increasing the secondary Pressure or decreasing primary Pressure. The opposite trends are found for Pressure Recovery ratio. Moreover, the critical area ratio varies greatly with the operation condition, and can be predicted by a linear fitting function of primary Pressure or a power function in terms of secondary Pressure.
-
numerical investigation of geometry parameters for Pressure Recovery of an adjustable ejector in multi evaporator refrigeration system
Applied Thermal Engineering, 2013Co-Authors: Jia Yan, Wenjian Cai, Chen Lin, Karunagaran GiridharanAbstract:Abstract In this paper, Computational Fluid Dynamics (CFD) technique is used to investigate the optimum geometry parameters of the adjustable ejector, which is used in variable cooling loads conditions, for the performance of Pressure Recovery in a multi-evaporator refrigeration system (EMERS) using R134a as the refrigerant. The performance of Pressure Recovery reflects the performance of the compression energy saving. The developed CFD model is first validated by actual experimental data of an EMERS. The k–ω–sst model is chosen as the turbulence model, and then used to find the optimum geometry parameters: nozzle diverging angle, length of the constant-Pressure mixing section, nozzle exit position and converging angle of the constant-Pressure mixing section, for high performance in Pressure Recovery properties. Through the analysis of physical mechanism, the results indicate that the Pressure Recovery ratio can be efficiently improved after the geometries optimization which is very sensitive to the nozzle diverging angle and the length of the constant-Pressure mixing section.
-
Experimental investigation of the adjustable ejector in a multi-evaporator refrigeration system
Applied Thermal Engineering, 2013Co-Authors: Chen Lin, Wenjian Cai, Jia YanAbstract:Abstract In this paper, the experimental investigation was carried out for the performance of adjustable ejector used in a multi-evaporator refrigeration system. The adjustable ejector with a spindle to adjust the area of nozzle throat was applied to deal with the considerable variation in primary cooling load for air-conditioning in such system. The adaptability of the adjustable ejector for the system was first evaluated by the tests and the results show the adjustable ejector can efficiently deal the problem of variable primary cooling load in the system. The tests for the performance of Pressure Recovery were subsequently carried out. The experimental results indicate that the Pressure Recovery Ratio (PRR) and Relative Pressure Recovery Ratio (RPRR) can reach 20% and 8%, respectively, in the system with design operating condition, which means the adjustable ejector applied in multi-evaporator refrigeration system may be a promising approach for a practical multi-evaporator refrigeration system with significant energy saving. It also can be found that PRR and RPRR are reduced with decreasing of the primary cooling load.
-
the characteristics of Pressure Recovery in an adjustable ejector multi evaporator refrigeration system
Energy, 2012Co-Authors: Chen Lin, Wenjian Cai, Jia YanAbstract:In this paper, Computational Fluid Dynamics (CFD) technique is used to investigate the adaption of adjustable ejector for variable cooling loads and the characteristics of ejector Pressure Recovery in a multi-evaporator refrigeration system (EMERS) using R134a as the refrigerant. The performance of Pressure Recovery reflects the performance of the compression energy saving. The developed CFD model is first validated by actual experimental data of an EMERS (ejector-based multi-evaporator refrigeration system). Turbulence model constants are carefully selected in order to minimize the model prediction error. The calibrated model is then solved to find the adaption property of the adjustable ejector and the effects of varying cooling loads on and the Pressure Recovery ratio. The results indicate that the adjustable ejector using spindle to adjust the throat area of primary nozzle is an efficient solution to control the primary operating Pressure in constant for system stability. Pressure Recovery ratio is sensitive to the varying of cooling loads and the relationship between them is then presented.
-
Pressure Recovery ratio in a variable cooling loads ejector based multi evaporator refrigeration system
Energy, 2012Co-Authors: Chen Lin, Wenjian Cai, Jia YanAbstract:In this paper, the Computational Fluid Dynamics (CFD) technique is used to investigate the influences of varying cooling loads on the ejector Pressure Recovery performance in an ejector-based multi-evaporator refrigeration system (EMERS) using R134a as the refrigerant. The performance of Pressure Recovery in the EMERS reflects the performance of the compression energy saving. The developed CFD model is first validated by actual experimental data from the EMERS. Turbulence model constants are carefully selected in order to minimize the model prediction error. Over 200 different cases are studied using the model to find the effects of varying cooling loads on Pressure Recovery ratio. The results indicate that Pressure Recovery ratio is very sensitive to the varying primary and secondary flow cooling loads. The maximum Pressure Recovery ratio can reach 60% as the cooling loads vary. It was found that in order to keep the system stable, the primary and secondary cooling loads should be maintained within ±5% and ±10%, respectively, in which case the Pressure Recovery ratio will have a maximum ratio of 32.8%.
Chen Lin - One of the best experts on this subject based on the ideXlab platform.
-
numerical investigation of geometry parameters for Pressure Recovery of an adjustable ejector in multi evaporator refrigeration system
Applied Thermal Engineering, 2013Co-Authors: Jia Yan, Wenjian Cai, Chen Lin, Karunagaran GiridharanAbstract:Abstract In this paper, Computational Fluid Dynamics (CFD) technique is used to investigate the optimum geometry parameters of the adjustable ejector, which is used in variable cooling loads conditions, for the performance of Pressure Recovery in a multi-evaporator refrigeration system (EMERS) using R134a as the refrigerant. The performance of Pressure Recovery reflects the performance of the compression energy saving. The developed CFD model is first validated by actual experimental data of an EMERS. The k–ω–sst model is chosen as the turbulence model, and then used to find the optimum geometry parameters: nozzle diverging angle, length of the constant-Pressure mixing section, nozzle exit position and converging angle of the constant-Pressure mixing section, for high performance in Pressure Recovery properties. Through the analysis of physical mechanism, the results indicate that the Pressure Recovery ratio can be efficiently improved after the geometries optimization which is very sensitive to the nozzle diverging angle and the length of the constant-Pressure mixing section.
-
Experimental investigation of the adjustable ejector in a multi-evaporator refrigeration system
Applied Thermal Engineering, 2013Co-Authors: Chen Lin, Wenjian Cai, Jia YanAbstract:Abstract In this paper, the experimental investigation was carried out for the performance of adjustable ejector used in a multi-evaporator refrigeration system. The adjustable ejector with a spindle to adjust the area of nozzle throat was applied to deal with the considerable variation in primary cooling load for air-conditioning in such system. The adaptability of the adjustable ejector for the system was first evaluated by the tests and the results show the adjustable ejector can efficiently deal the problem of variable primary cooling load in the system. The tests for the performance of Pressure Recovery were subsequently carried out. The experimental results indicate that the Pressure Recovery Ratio (PRR) and Relative Pressure Recovery Ratio (RPRR) can reach 20% and 8%, respectively, in the system with design operating condition, which means the adjustable ejector applied in multi-evaporator refrigeration system may be a promising approach for a practical multi-evaporator refrigeration system with significant energy saving. It also can be found that PRR and RPRR are reduced with decreasing of the primary cooling load.
-
the characteristics of Pressure Recovery in an adjustable ejector multi evaporator refrigeration system
Energy, 2012Co-Authors: Chen Lin, Wenjian Cai, Jia YanAbstract:In this paper, Computational Fluid Dynamics (CFD) technique is used to investigate the adaption of adjustable ejector for variable cooling loads and the characteristics of ejector Pressure Recovery in a multi-evaporator refrigeration system (EMERS) using R134a as the refrigerant. The performance of Pressure Recovery reflects the performance of the compression energy saving. The developed CFD model is first validated by actual experimental data of an EMERS (ejector-based multi-evaporator refrigeration system). Turbulence model constants are carefully selected in order to minimize the model prediction error. The calibrated model is then solved to find the adaption property of the adjustable ejector and the effects of varying cooling loads on and the Pressure Recovery ratio. The results indicate that the adjustable ejector using spindle to adjust the throat area of primary nozzle is an efficient solution to control the primary operating Pressure in constant for system stability. Pressure Recovery ratio is sensitive to the varying of cooling loads and the relationship between them is then presented.
-
Pressure Recovery ratio in a variable cooling loads ejector based multi evaporator refrigeration system
Energy, 2012Co-Authors: Chen Lin, Wenjian Cai, Jia YanAbstract:In this paper, the Computational Fluid Dynamics (CFD) technique is used to investigate the influences of varying cooling loads on the ejector Pressure Recovery performance in an ejector-based multi-evaporator refrigeration system (EMERS) using R134a as the refrigerant. The performance of Pressure Recovery in the EMERS reflects the performance of the compression energy saving. The developed CFD model is first validated by actual experimental data from the EMERS. Turbulence model constants are carefully selected in order to minimize the model prediction error. Over 200 different cases are studied using the model to find the effects of varying cooling loads on Pressure Recovery ratio. The results indicate that Pressure Recovery ratio is very sensitive to the varying primary and secondary flow cooling loads. The maximum Pressure Recovery ratio can reach 60% as the cooling loads vary. It was found that in order to keep the system stable, the primary and secondary cooling loads should be maintained within ±5% and ±10%, respectively, in which case the Pressure Recovery ratio will have a maximum ratio of 32.8%.
N A Cumpsty - One of the best experts on this subject based on the ideXlab platform.
-
effects of inlet flow field conditions on the performance of centrifugal compressor diffusers part 1 discrete passage diffuser
Journal of Turbomachinery-transactions of The Asme, 2000Co-Authors: V G Filipenco, Sabri Deniz, E M Greitzer, J M Johnston, N A CumpstyAbstract:This is Part 1 of a two-part paper considering the performance of radial diffusers for use in a high-performance centrifugal compressor. Part 1 reports on discrete-passage diffusers (shown in Fig. 1) while Part 2 describes a test of a straight-channel diffuser designed for equivalent duty. Two builds of discrete-passage diffuser were tested, with 30 and 38 separate passages. Both the 30 and 38 passage diffusers investigated showed comparable range of unstalled operation and similar level of overall diffuser Pressure Recovery. The paper concentrates on the influence of inlet flow conditions on the Pressure Recovery and operating range of radial diffusers for centrifugal compressor stages. The flow conditions examined include diffuser inlet Mach number, flow angle, blockage, and axial flow nonuniformity. The investigation was carried out in a specially built test facility, designed to provide a controlled inlet flow field to the test diffusers. The facility can provide a wide range of diffuser inlet velocity profile distortion and skew with Mach numbers up to unity and flow angles of 63 to 75 deg from the radial direction. The consequences of different averaging methods for the inlet total Pressure distributions, which are needed in the definition of diffuser Pressure Recovery coefficient for nonuniform diffuser inlet conditions, were also assessed. The overall diffuser Pressure Recovery coefficient, based on suitably averaged inlet total Pressure, was found to correlate well with the momentum-averaged flow angle into the diffuser. Furthermore, the Pressure Recovery coefficient was found to be essentially independent of the axial distortion at diffuser inlet, and the Mach number, over the wide flow range (from maximum flow to the beginning of flow instabilities) investigated. It is thus shown that the generally accepted sensitivity of diffuser Pressure Recovery performance to inlet flow distortion and boundary layer blockage can be largely attributed to inappropriate quantification of the average dynamic Pressure at diffuser inlet. Use of an inlet dynamic Pressure based on availability or mass-averaging in combination with definition of inlet flow angle based on mass average of the radial and tangential velocity at diffuser inlet removes this sensitivity.
-
effects of inlet flow field conditions on the performance of centrifugal compressor diffusers part 2 straight channel diffuser
Journal of Turbomachinery-transactions of The Asme, 2000Co-Authors: Sabri Deniz, E M Greitzer, N A CumpstyAbstract:This is Part 2 of an examination of the influence of inlet flow conditions on the performance and operating range of centrifugal compressor vaned diffusers. The paper describes tests of a straight-channel type diffuser, sometimes called a wedge-vane diffuser, and compares the results with those from the discrete-passage diffusers described in Part 1. Effects of diffuser inlet Mach number, flow angle, blockage, and axial flow nonuniformity on diffuser Pressure Recovery and operating range are addressed. The straight-channel diffuser investigated has 30 vanes and was designed for the same aerodynamic duty as the discrete-passage diffuser described in Part 1. The ranges of the overall Pressure Recovery coefficients were 0.50-0.78 for the straight-channel diffuser and 0.50-0.70 for the discrete-passage diffuser, except when the diffuser was choked. In other words, the maximum Pressure Recovery of the straight-channel diffuser was found to be roughly 10 percent higher than that of the discrete-passage diffuser investigated. The two types of diffuser showed similar behavior regarding the dependence of Pressure Recovery on diffuser inlet flow angle and the insensitivity of the performance to inlet flow field axial distortion and Mach number. The operating range of the straight-channel diffuser, as for the discrete-passage diffusers, was limited by the onset of rotating stall at a fixed momentum-averaged flow angle into the diffuser, which was for the straight-channel diffuser, α crit = 70 ± 0.5 deg. The background, nomenclature, and description of the facility and method are all given in Part 1.
-
effects of inlet flow field conditions on the performance of centrifugal compressor diffusers part 2 straight channel diffuser
ASME 1998 International Gas Turbine and Aeroengine Congress and Exhibition, 1998Co-Authors: Sabri Deniz, E M Greitzer, N A CumpstyAbstract:This is Part 2 of an examination of influence of inlet flow conditions on the performance and operating range of centrifugal compressor vaned diffusers. The paper describes tests of straight-channel type diffuser, sometimes called a wedge-vane diffuser, and compares the results with those from the discrete-passage diffusers described in Part 1. Effects of diffuser inlet Mach number, flow angle, blockage, and axial flow non-uniformity on diffuser Pressure Recovery and operating range are addressed.The straight-channel diffuser investigated has 30 vanes and was designed for the same aerodynamic duty as the discrete-passage diffuser described in Part 1. The ranges of the overall Pressure Recovery coefficients were 0.65–0.78 for the straight-channel diffuser and 0.60–0.70 for the discrete-passage diffuser; the Pressure Recovery of the straight-channel diffuser was roughly 10% higher than that of the discrete-passage diffuser. Both types of the diffusers showed similar behavior regarding the dependence on diffuser inlet flow angle and the insensitivity of the performance to inlet flow field axial distortion and Mach number. The operating range of the straight-channel diffuser, as for the discrete-passage diffusers was limited by the onset of rotating stall at a fixed momentum-averaged flow angle into the diffuser, which was for the straight-channel diffuser, αcrit = 70° ±0.5°.The background, nomenclature and description of the facility and method are all given in Part 1.Copyright © 1998 by ASME
Wenjian Cai - One of the best experts on this subject based on the ideXlab platform.
-
analysis on performance characteristics of ejector with variable area ratio for multi evaporator refrigeration system based on experimental data
Applied Thermal Engineering, 2014Co-Authors: Wenjian Cai, Haoran Chen, Jia YanAbstract:Abstract This paper presents a study on experiment and analysis of variable area-ratio ejector used in a multi-evaporator refrigeration system (MERS). The experimental rig and method are described, and the entrainment and Pressure Recovery performances of the variable ejector are measured at various operating and geometric conditions. The critical area ratio is proposed as an indicator of Pressure Recovery status; area ratios smaller than the critical ones are required to make sure that the system operates at energy saving mode. The investigation results indicate that the entrainment ratio, Pressure Recovery ratio and critical area ratio are strongly affected by the primary Pressure and secondary Pressure. Greater entrainment ratio can be obtained by increasing the secondary Pressure or decreasing primary Pressure. The opposite trends are found for Pressure Recovery ratio. Moreover, the critical area ratio varies greatly with the operation condition, and can be predicted by a linear fitting function of primary Pressure or a power function in terms of secondary Pressure.
-
numerical investigation of geometry parameters for Pressure Recovery of an adjustable ejector in multi evaporator refrigeration system
Applied Thermal Engineering, 2013Co-Authors: Jia Yan, Wenjian Cai, Chen Lin, Karunagaran GiridharanAbstract:Abstract In this paper, Computational Fluid Dynamics (CFD) technique is used to investigate the optimum geometry parameters of the adjustable ejector, which is used in variable cooling loads conditions, for the performance of Pressure Recovery in a multi-evaporator refrigeration system (EMERS) using R134a as the refrigerant. The performance of Pressure Recovery reflects the performance of the compression energy saving. The developed CFD model is first validated by actual experimental data of an EMERS. The k–ω–sst model is chosen as the turbulence model, and then used to find the optimum geometry parameters: nozzle diverging angle, length of the constant-Pressure mixing section, nozzle exit position and converging angle of the constant-Pressure mixing section, for high performance in Pressure Recovery properties. Through the analysis of physical mechanism, the results indicate that the Pressure Recovery ratio can be efficiently improved after the geometries optimization which is very sensitive to the nozzle diverging angle and the length of the constant-Pressure mixing section.
-
Experimental investigation of the adjustable ejector in a multi-evaporator refrigeration system
Applied Thermal Engineering, 2013Co-Authors: Chen Lin, Wenjian Cai, Jia YanAbstract:Abstract In this paper, the experimental investigation was carried out for the performance of adjustable ejector used in a multi-evaporator refrigeration system. The adjustable ejector with a spindle to adjust the area of nozzle throat was applied to deal with the considerable variation in primary cooling load for air-conditioning in such system. The adaptability of the adjustable ejector for the system was first evaluated by the tests and the results show the adjustable ejector can efficiently deal the problem of variable primary cooling load in the system. The tests for the performance of Pressure Recovery were subsequently carried out. The experimental results indicate that the Pressure Recovery Ratio (PRR) and Relative Pressure Recovery Ratio (RPRR) can reach 20% and 8%, respectively, in the system with design operating condition, which means the adjustable ejector applied in multi-evaporator refrigeration system may be a promising approach for a practical multi-evaporator refrigeration system with significant energy saving. It also can be found that PRR and RPRR are reduced with decreasing of the primary cooling load.
-
the characteristics of Pressure Recovery in an adjustable ejector multi evaporator refrigeration system
Energy, 2012Co-Authors: Chen Lin, Wenjian Cai, Jia YanAbstract:In this paper, Computational Fluid Dynamics (CFD) technique is used to investigate the adaption of adjustable ejector for variable cooling loads and the characteristics of ejector Pressure Recovery in a multi-evaporator refrigeration system (EMERS) using R134a as the refrigerant. The performance of Pressure Recovery reflects the performance of the compression energy saving. The developed CFD model is first validated by actual experimental data of an EMERS (ejector-based multi-evaporator refrigeration system). Turbulence model constants are carefully selected in order to minimize the model prediction error. The calibrated model is then solved to find the adaption property of the adjustable ejector and the effects of varying cooling loads on and the Pressure Recovery ratio. The results indicate that the adjustable ejector using spindle to adjust the throat area of primary nozzle is an efficient solution to control the primary operating Pressure in constant for system stability. Pressure Recovery ratio is sensitive to the varying of cooling loads and the relationship between them is then presented.
-
Pressure Recovery ratio in a variable cooling loads ejector based multi evaporator refrigeration system
Energy, 2012Co-Authors: Chen Lin, Wenjian Cai, Jia YanAbstract:In this paper, the Computational Fluid Dynamics (CFD) technique is used to investigate the influences of varying cooling loads on the ejector Pressure Recovery performance in an ejector-based multi-evaporator refrigeration system (EMERS) using R134a as the refrigerant. The performance of Pressure Recovery in the EMERS reflects the performance of the compression energy saving. The developed CFD model is first validated by actual experimental data from the EMERS. Turbulence model constants are carefully selected in order to minimize the model prediction error. Over 200 different cases are studied using the model to find the effects of varying cooling loads on Pressure Recovery ratio. The results indicate that Pressure Recovery ratio is very sensitive to the varying primary and secondary flow cooling loads. The maximum Pressure Recovery ratio can reach 60% as the cooling loads vary. It was found that in order to keep the system stable, the primary and secondary cooling loads should be maintained within ±5% and ±10%, respectively, in which case the Pressure Recovery ratio will have a maximum ratio of 32.8%.
Karunagaran Giridharan - One of the best experts on this subject based on the ideXlab platform.
-
numerical investigation of geometry parameters for Pressure Recovery of an adjustable ejector in multi evaporator refrigeration system
Applied Thermal Engineering, 2013Co-Authors: Yanzhong Li, Yu Hu, Karunagaran GiridharanAbstract:Abstract In this paper, Computational Fluid Dynamics (CFD) technique is used to investigate the optimum geometry parameters of the adjustable ejector, which is used in variable cooling loads conditions, for the performance of Pressure Recovery in a multi-evaporator refrigeration system (EMERS) using R134a as the refrigerant. The performance of Pressure Recovery reflects the performance of the compression energy saving. The developed CFD model is first validated by actual experimental data of an EMERS. The k–ω–sst model is chosen as the turbulence model, and then used to find the optimum geometry parameters: nozzle diverging angle, length of the constant-Pressure mixing section, nozzle exit position and converging angle of the constant-Pressure mixing section, for high performance in Pressure Recovery properties. Through the analysis of physical mechanism, the results indicate that the Pressure Recovery ratio can be efficiently improved after the geometries optimization which is very sensitive to the nozzle diverging angle and the length of the constant-Pressure mixing section.
-
numerical investigation of geometry parameters for Pressure Recovery of an adjustable ejector in multi evaporator refrigeration system
Applied Thermal Engineering, 2013Co-Authors: Jia Yan, Wenjian Cai, Chen Lin, Karunagaran GiridharanAbstract:Abstract In this paper, Computational Fluid Dynamics (CFD) technique is used to investigate the optimum geometry parameters of the adjustable ejector, which is used in variable cooling loads conditions, for the performance of Pressure Recovery in a multi-evaporator refrigeration system (EMERS) using R134a as the refrigerant. The performance of Pressure Recovery reflects the performance of the compression energy saving. The developed CFD model is first validated by actual experimental data of an EMERS. The k–ω–sst model is chosen as the turbulence model, and then used to find the optimum geometry parameters: nozzle diverging angle, length of the constant-Pressure mixing section, nozzle exit position and converging angle of the constant-Pressure mixing section, for high performance in Pressure Recovery properties. Through the analysis of physical mechanism, the results indicate that the Pressure Recovery ratio can be efficiently improved after the geometries optimization which is very sensitive to the nozzle diverging angle and the length of the constant-Pressure mixing section.