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Banasiak Krzysztof - One of the best experts on this subject based on the ideXlab platform.
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Non-equilibrium approach in simulations of the R744 flow through the motive Nozzle of the two-phase ejector
'Siirt Universitesi Sosyal Bilimler Enstitusu Dergisi', 2020Co-Authors: Bodys Jakub, Smolka Jacek, Palacz Michał, Haida Michal, Banasiak KrzysztofAbstract:The ejector technology for R744 systems was continuously improved over the last two decades in the area of control and design processes. The latter should be related with a significant interest on modelling approaches including numerical simulations. However, some limitations of the existing approaches are still present, while the application range of the ejectors is still increasing regarding mobile and domestic applications. Namely, a quality of the flow prediction in the transcritical two-phase ejector varies depending on the operating conditions and correlated phenomena. The accurate and time efficient computational approach including the operating range of low condensing pressures is presented with the aim of more effective ejector design. The mixture approach developed on the basis of the Homogeneous Equilibrium Model is described regarding prediction of the motive and Suction mass flow rate which are crucial for proper control procedures of the ejector-based refrigeration cycle. Additional equation for the vapour quality transport and re-formulated property definitions are utilised for proper control of the evaporation process in the motive Nozzle of the ejector. Coefficients in source terms of the quality equation were mapped regarding high accuracy of the motive mass flow rate prediction. Hence, the calibration procedure of the coefficients, resulting in an approximation function as well as mapping of the Suction Nozzle accuracy regarding turbulence modelling and cavitation phenomena are introduced in this study. Finally, a comparison with the baseline homogeneous equilibrium model is given on the basis of the mass flow rate prediction and field parameters. Keywords: Carbon Dioxide, Transcritical Ejector, Phase change modelling, Expansion modellin
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Non-equilibrium approach in simulations of the R744 flow through the motive Nozzle of the two-phase ejector
IIR, 2020Co-Authors: Bodys Jakub, Smolka Jacek, Palacz Michał, Haida Michal, Banasiak KrzysztofAbstract:The ejector technology for R744 systems was continuously improved over the last two decades in the area of control and design processes. The latter should be related with a significant interest on modelling approaches including numerical simulations. However, some limitations of the existing approaches are still present, while the application range of the ejectors is still increasing regarding mobile and domestic applications. Namely, a quality of the flow prediction in the transcritical two-phase ejector varies depending on the operating conditions and correlated phenomena. The accurate and time efficient computational approach including the operating range of low condensing pressures is presented with the aim of more effective ejector design. The mixture approach developed on the basis of the Homogeneous Equilibrium Model is described regarding prediction of the motive and Suction mass flow rate which are crucial for proper control procedures of the ejector-based refrigeration cycle. Additional equation for the vapour quality transport and re-formulated property definitions are utilised for proper control of the evaporation process in the motive Nozzle of the ejector. Coefficients in source terms of the quality equation were mapped regarding high accuracy of the motive mass flow rate prediction. Hence, the calibration procedure of the coefficients, resulting in an approximation function as well as mapping of the Suction Nozzle accuracy regarding turbulence modelling and cavitation phenomena are introduced in this study. Finally, a comparison with the baseline homogeneous equilibrium model is given on the basis of the mass flow rate prediction and field parameters. Keywords: Carbon Dioxide, Transcritical Ejector, Phase change modelling, Expansion modellingacceptedVersio
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Numerical investigation of heat transfer in a CO2 two-phase ejector
'Elsevier BV', 2018Co-Authors: Haida Michal, Smolka Jacek, Hafner Armin, Mastrowski Mikolaj, Palacz Michal, Madsen, Kenneth B., Nowak, Andrzej J., Banasiak KrzysztofAbstract:In this paper, the influence of heat transfer in the walls of an R744 two-phase ejector on ejector performance was investigated. A numerical investigation was performed using a computational fluid dynamic (CFD) model of the R744 two-phase flow coupled with the heat transfer inside the ejector. An ejector equipped with thermocouple channels was designed and manufactured to investigate temperature distribution in the inner walls under boundary conditions typical for a refrigeration and air-conditioning application in a supermarket. The ejector was installed on the test rig to perform a test series that evaluated the outer walls of the ejector with and without insulation. The experimental results were used to validate the proposed CFD model, and a numerical investigation was performed to analyse the influence of heat transfer on ejector performance. The motive Nozzle and Suction Nozzle mass flow rates accuracies were within ±7% and ±15%, respectively. In addition, the proposed CFD model predicted the wall temperatures with ±5 K accuracy for most of the validated points. The heat transfer coefficient of the R744 two-phase flow inside the ejector is presented. The non-adiabatic inner walls degraded ejector performance. The maximum reduction of the mass entrainment ratio reached approximately 13%. © 2018 Elsevier Ltd. All rights reservedNumerical investigation of heat transfer in a CO2 two-phase ejectoracceptedVersio
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Performance improvement of the R744 two-phase ejector With a implemented Suction Nozzle bypass
'Elsevier BV', 2018Co-Authors: Bodys Jakub, Smolka Jacek, Banasiak Krzysztof, Palacz Michal, Nowak, Andrzej J.Abstract:In this study, the concept of an R744 ejector with a bypass duct of a Suction Nozzle was presented. The design of the geometry and bypass positioning in a mixing section, and the idea of regulation, as well as integration, with a Suction Nozzle duct was described. A preliminary numerical analysis of the proposed bypass geometry was also presented. The computational platform ejectorPL integrated with an extensively validated mathematical model of transcritical R744 two-phase flow was used. Motive Nozzle inlet and Suction Nozzle inlet conditions reflecting gas cooler and evaporator conditions characteristic of large systems, such as supermarket refrigeration units, were examined. Three different separation pressures in liquid receivers were assumed for two bypass geometries and six bypass inlet positions. The bypass positioning as a function of a mixer length was presented. Uniquely positive results were obtained for the lowest pressure conditions. Namely, the increment of the Suction mass flow rate was substantial and equal to 36.9% for the bypass angle of 19°. Hence, the bypass implementation resulted in distinct potential of an efficiency improvement - from 22.2% to 30.4%. A higher pressure lift case did not result in any improvement of the ejector work. The influence of the bypass geometry on the overall ejector efficiency was preliminarily characterised. Finally, the pressure distribution in the bypass type ejector was described.acceptedVersio
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Performance improvement of the R744 two-phase ejector With a implemented Suction Nozzle bypass
'Elsevier BV', 2018Co-Authors: Bodys Jakub, Smolka Jacek, Banasiak Krzysztof, Palacz Michal, Nowak, Andrzej J.Abstract:In this study, the concept of an R744 ejector with a bypass duct of a Suction Nozzle was presented. The design of the geometry and bypass positioning in a mixing section, and the idea of regulation, as well as integration, with a Suction Nozzle duct was described. A preliminary numerical analysis of the proposed bypass geometry was also presented. The computational platform ejectorPL integrated with an extensively validated mathematical model of transcritical R744 two-phase flow was used. Motive Nozzle inlet and Suction Nozzle inlet conditions reflecting gas cooler and evaporator conditions characteristic of large systems, such as supermarket refrigeration units, were examined. Three different separation pressures in liquid receivers were assumed for two bypass geometries and six bypass inlet positions. The bypass positioning as a function of a mixer length was presented. Uniquely positive results were obtained for the lowest pressure conditions. Namely, the increment of the Suction mass flow rate was substantial and equal to 36.9% for the bypass angle of 19°. Hence, the bypass implementation resulted in distinct potential of an efficiency improvement - from 22.2% to 30.4%. A higher pressure lift case did not result in any improvement of the ejector work. The influence of the bypass geometry on the overall ejector efficiency was preliminarily characterised. Finally, the pressure distribution in the bypass type ejector was described
Nowak, Andrzej J. - One of the best experts on this subject based on the ideXlab platform.
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Experimental Test Rig For The Visualisation Study Of The Transcritical Flow In The Two-Phase R744 Ejectors
'Purdue University (bepress)', 2021Co-Authors: Bodys Jakub, Smolka Jacek, Palacz Michał, Haida Michał, Nowak, Andrzej J.Abstract:Recent studies have provided the significant number of approaches to enhance the performance of a twophase ejector, especially for transcritical CO2 cycles. However, the investigation of the mixing process is still challenging matter due to the highspeed fluid flow coupled with mixing of vapour and partially evaporated liquid stream. On the other hand, these phenomena directly influence the ejector efficiency. The behaviour of the aforementioned processes would be valuable for validation the numerical models as well as a required control of the system operation. Hence, in this work, the laboratory test rig for visualisation of the CO2 ejector mixing processes along Suction Nozzle, premixing chamber and diffuser was developed and manufactured. The visualisation techniques used for this study include the highspeed camera recordings and PIV measurements. The work consists of installation description, including the measurement approaches, solution predicted by the computational model for the transparent construction of the ejector and visualisation procedures. The selected onand offdesign operating points were described having regard ejector performance factors and its correlation with the output of the visualisation procedure
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Numerical investigation of heat transfer in a CO2 two-phase ejector
'Elsevier BV', 2018Co-Authors: Haida Michal, Smolka Jacek, Hafner Armin, Mastrowski Mikolaj, Palacz Michal, Madsen, Kenneth B., Nowak, Andrzej J., Banasiak KrzysztofAbstract:In this paper, the influence of heat transfer in the walls of an R744 two-phase ejector on ejector performance was investigated. A numerical investigation was performed using a computational fluid dynamic (CFD) model of the R744 two-phase flow coupled with the heat transfer inside the ejector. An ejector equipped with thermocouple channels was designed and manufactured to investigate temperature distribution in the inner walls under boundary conditions typical for a refrigeration and air-conditioning application in a supermarket. The ejector was installed on the test rig to perform a test series that evaluated the outer walls of the ejector with and without insulation. The experimental results were used to validate the proposed CFD model, and a numerical investigation was performed to analyse the influence of heat transfer on ejector performance. The motive Nozzle and Suction Nozzle mass flow rates accuracies were within ±7% and ±15%, respectively. In addition, the proposed CFD model predicted the wall temperatures with ±5 K accuracy for most of the validated points. The heat transfer coefficient of the R744 two-phase flow inside the ejector is presented. The non-adiabatic inner walls degraded ejector performance. The maximum reduction of the mass entrainment ratio reached approximately 13%. © 2018 Elsevier Ltd. All rights reservedNumerical investigation of heat transfer in a CO2 two-phase ejectoracceptedVersio
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Performance improvement of the R744 two-phase ejector With a implemented Suction Nozzle bypass
'Elsevier BV', 2018Co-Authors: Bodys Jakub, Smolka Jacek, Banasiak Krzysztof, Palacz Michal, Nowak, Andrzej J.Abstract:In this study, the concept of an R744 ejector with a bypass duct of a Suction Nozzle was presented. The design of the geometry and bypass positioning in a mixing section, and the idea of regulation, as well as integration, with a Suction Nozzle duct was described. A preliminary numerical analysis of the proposed bypass geometry was also presented. The computational platform ejectorPL integrated with an extensively validated mathematical model of transcritical R744 two-phase flow was used. Motive Nozzle inlet and Suction Nozzle inlet conditions reflecting gas cooler and evaporator conditions characteristic of large systems, such as supermarket refrigeration units, were examined. Three different separation pressures in liquid receivers were assumed for two bypass geometries and six bypass inlet positions. The bypass positioning as a function of a mixer length was presented. Uniquely positive results were obtained for the lowest pressure conditions. Namely, the increment of the Suction mass flow rate was substantial and equal to 36.9% for the bypass angle of 19°. Hence, the bypass implementation resulted in distinct potential of an efficiency improvement - from 22.2% to 30.4%. A higher pressure lift case did not result in any improvement of the ejector work. The influence of the bypass geometry on the overall ejector efficiency was preliminarily characterised. Finally, the pressure distribution in the bypass type ejector was described.acceptedVersio
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Performance improvement of the R744 two-phase ejector With a implemented Suction Nozzle bypass
'Elsevier BV', 2018Co-Authors: Bodys Jakub, Smolka Jacek, Banasiak Krzysztof, Palacz Michal, Nowak, Andrzej J.Abstract:In this study, the concept of an R744 ejector with a bypass duct of a Suction Nozzle was presented. The design of the geometry and bypass positioning in a mixing section, and the idea of regulation, as well as integration, with a Suction Nozzle duct was described. A preliminary numerical analysis of the proposed bypass geometry was also presented. The computational platform ejectorPL integrated with an extensively validated mathematical model of transcritical R744 two-phase flow was used. Motive Nozzle inlet and Suction Nozzle inlet conditions reflecting gas cooler and evaporator conditions characteristic of large systems, such as supermarket refrigeration units, were examined. Three different separation pressures in liquid receivers were assumed for two bypass geometries and six bypass inlet positions. The bypass positioning as a function of a mixer length was presented. Uniquely positive results were obtained for the lowest pressure conditions. Namely, the increment of the Suction mass flow rate was substantial and equal to 36.9% for the bypass angle of 19°. Hence, the bypass implementation resulted in distinct potential of an efficiency improvement - from 22.2% to 30.4%. A higher pressure lift case did not result in any improvement of the ejector work. The influence of the bypass geometry on the overall ejector efficiency was preliminarily characterised. Finally, the pressure distribution in the bypass type ejector was described
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Numerical investigation of heat transfer in a CO2 two-phase ejector
'Elsevier BV', 2018Co-Authors: Haida Michal, Smolka Jacek, Hafner Armin, Mastrowski Mikolaj, Palacz Michal, Madsen, Kenneth B., Nowak, Andrzej J., Banasiak KrzysztofAbstract:In this paper, the influence of heat transfer in the walls of an R744 two-phase ejector on ejector performance was investigated. A numerical investigation was performed using a computational fluid dynamic (CFD) model of the R744 two-phase flow coupled with the heat transfer inside the ejector. An ejector equipped with thermocouple channels was designed and manufactured to investigate temperature distribution in the inner walls under boundary conditions typical for a refrigeration and air-conditioning application in a supermarket. The ejector was installed on the test rig to perform a test series that evaluated the outer walls of the ejector with and without insulation. The experimental results were used to validate the proposed CFD model, and a numerical investigation was performed to analyse the influence of heat transfer on ejector performance. The motive Nozzle and Suction Nozzle mass flow rates accuracies were within ±7% and ±15%, respectively. In addition, the proposed CFD model predicted the wall temperatures with ±5 K accuracy for most of the validated points. The heat transfer coefficient of the R744 two-phase flow inside the ejector is presented. The non-adiabatic inner walls degraded ejector performance. The maximum reduction of the mass entrainment ratio reached approximately 13%. © 2018 Elsevier Ltd. All rights reserve
Smolka Jacek - One of the best experts on this subject based on the ideXlab platform.
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Experimental Test Rig For The Visualisation Study Of The Transcritical Flow In The Two-Phase R744 Ejectors
'Purdue University (bepress)', 2021Co-Authors: Bodys Jakub, Smolka Jacek, Palacz Michał, Haida Michał, Nowak, Andrzej J.Abstract:Recent studies have provided the significant number of approaches to enhance the performance of a twophase ejector, especially for transcritical CO2 cycles. However, the investigation of the mixing process is still challenging matter due to the highspeed fluid flow coupled with mixing of vapour and partially evaporated liquid stream. On the other hand, these phenomena directly influence the ejector efficiency. The behaviour of the aforementioned processes would be valuable for validation the numerical models as well as a required control of the system operation. Hence, in this work, the laboratory test rig for visualisation of the CO2 ejector mixing processes along Suction Nozzle, premixing chamber and diffuser was developed and manufactured. The visualisation techniques used for this study include the highspeed camera recordings and PIV measurements. The work consists of installation description, including the measurement approaches, solution predicted by the computational model for the transparent construction of the ejector and visualisation procedures. The selected onand offdesign operating points were described having regard ejector performance factors and its correlation with the output of the visualisation procedure
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Non-equilibrium approach in simulations of the R744 flow through the motive Nozzle of the two-phase ejector
'Siirt Universitesi Sosyal Bilimler Enstitusu Dergisi', 2020Co-Authors: Bodys Jakub, Smolka Jacek, Palacz Michał, Haida Michal, Banasiak KrzysztofAbstract:The ejector technology for R744 systems was continuously improved over the last two decades in the area of control and design processes. The latter should be related with a significant interest on modelling approaches including numerical simulations. However, some limitations of the existing approaches are still present, while the application range of the ejectors is still increasing regarding mobile and domestic applications. Namely, a quality of the flow prediction in the transcritical two-phase ejector varies depending on the operating conditions and correlated phenomena. The accurate and time efficient computational approach including the operating range of low condensing pressures is presented with the aim of more effective ejector design. The mixture approach developed on the basis of the Homogeneous Equilibrium Model is described regarding prediction of the motive and Suction mass flow rate which are crucial for proper control procedures of the ejector-based refrigeration cycle. Additional equation for the vapour quality transport and re-formulated property definitions are utilised for proper control of the evaporation process in the motive Nozzle of the ejector. Coefficients in source terms of the quality equation were mapped regarding high accuracy of the motive mass flow rate prediction. Hence, the calibration procedure of the coefficients, resulting in an approximation function as well as mapping of the Suction Nozzle accuracy regarding turbulence modelling and cavitation phenomena are introduced in this study. Finally, a comparison with the baseline homogeneous equilibrium model is given on the basis of the mass flow rate prediction and field parameters. Keywords: Carbon Dioxide, Transcritical Ejector, Phase change modelling, Expansion modellin
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Non-equilibrium approach in simulations of the R744 flow through the motive Nozzle of the two-phase ejector
IIR, 2020Co-Authors: Bodys Jakub, Smolka Jacek, Palacz Michał, Haida Michal, Banasiak KrzysztofAbstract:The ejector technology for R744 systems was continuously improved over the last two decades in the area of control and design processes. The latter should be related with a significant interest on modelling approaches including numerical simulations. However, some limitations of the existing approaches are still present, while the application range of the ejectors is still increasing regarding mobile and domestic applications. Namely, a quality of the flow prediction in the transcritical two-phase ejector varies depending on the operating conditions and correlated phenomena. The accurate and time efficient computational approach including the operating range of low condensing pressures is presented with the aim of more effective ejector design. The mixture approach developed on the basis of the Homogeneous Equilibrium Model is described regarding prediction of the motive and Suction mass flow rate which are crucial for proper control procedures of the ejector-based refrigeration cycle. Additional equation for the vapour quality transport and re-formulated property definitions are utilised for proper control of the evaporation process in the motive Nozzle of the ejector. Coefficients in source terms of the quality equation were mapped regarding high accuracy of the motive mass flow rate prediction. Hence, the calibration procedure of the coefficients, resulting in an approximation function as well as mapping of the Suction Nozzle accuracy regarding turbulence modelling and cavitation phenomena are introduced in this study. Finally, a comparison with the baseline homogeneous equilibrium model is given on the basis of the mass flow rate prediction and field parameters. Keywords: Carbon Dioxide, Transcritical Ejector, Phase change modelling, Expansion modellingacceptedVersio
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Numerical investigation of heat transfer in a CO2 two-phase ejector
'Elsevier BV', 2018Co-Authors: Haida Michal, Smolka Jacek, Hafner Armin, Mastrowski Mikolaj, Palacz Michal, Madsen, Kenneth B., Nowak, Andrzej J., Banasiak KrzysztofAbstract:In this paper, the influence of heat transfer in the walls of an R744 two-phase ejector on ejector performance was investigated. A numerical investigation was performed using a computational fluid dynamic (CFD) model of the R744 two-phase flow coupled with the heat transfer inside the ejector. An ejector equipped with thermocouple channels was designed and manufactured to investigate temperature distribution in the inner walls under boundary conditions typical for a refrigeration and air-conditioning application in a supermarket. The ejector was installed on the test rig to perform a test series that evaluated the outer walls of the ejector with and without insulation. The experimental results were used to validate the proposed CFD model, and a numerical investigation was performed to analyse the influence of heat transfer on ejector performance. The motive Nozzle and Suction Nozzle mass flow rates accuracies were within ±7% and ±15%, respectively. In addition, the proposed CFD model predicted the wall temperatures with ±5 K accuracy for most of the validated points. The heat transfer coefficient of the R744 two-phase flow inside the ejector is presented. The non-adiabatic inner walls degraded ejector performance. The maximum reduction of the mass entrainment ratio reached approximately 13%. © 2018 Elsevier Ltd. All rights reservedNumerical investigation of heat transfer in a CO2 two-phase ejectoracceptedVersio
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Performance improvement of the R744 two-phase ejector With a implemented Suction Nozzle bypass
'Elsevier BV', 2018Co-Authors: Bodys Jakub, Smolka Jacek, Banasiak Krzysztof, Palacz Michal, Nowak, Andrzej J.Abstract:In this study, the concept of an R744 ejector with a bypass duct of a Suction Nozzle was presented. The design of the geometry and bypass positioning in a mixing section, and the idea of regulation, as well as integration, with a Suction Nozzle duct was described. A preliminary numerical analysis of the proposed bypass geometry was also presented. The computational platform ejectorPL integrated with an extensively validated mathematical model of transcritical R744 two-phase flow was used. Motive Nozzle inlet and Suction Nozzle inlet conditions reflecting gas cooler and evaporator conditions characteristic of large systems, such as supermarket refrigeration units, were examined. Three different separation pressures in liquid receivers were assumed for two bypass geometries and six bypass inlet positions. The bypass positioning as a function of a mixer length was presented. Uniquely positive results were obtained for the lowest pressure conditions. Namely, the increment of the Suction mass flow rate was substantial and equal to 36.9% for the bypass angle of 19°. Hence, the bypass implementation resulted in distinct potential of an efficiency improvement - from 22.2% to 30.4%. A higher pressure lift case did not result in any improvement of the ejector work. The influence of the bypass geometry on the overall ejector efficiency was preliminarily characterised. Finally, the pressure distribution in the bypass type ejector was described.acceptedVersio
D Y Li - One of the best experts on this subject based on the ideXlab platform.
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analysis for the ejector used as expansion valve in vapor compression refrigeration cycle
Applied Thermal Engineering, 2016Co-Authors: Fei Wang, D Y LiAbstract:Abstract An ejector was used in a compression refrigeration cycle for improving its efficiency. A constant-pressure mixing model was adopted to simulate the ejector. Whether or not the entrained flow would be choked at the outlet of the Suction Nozzle and whether or not a condensation shock would happen at the end of the mixing chamber were both considered. The effect of the mixing pressure on the performances of the ejector and the hybrid system was evaluated. The mixing pressure was finally determined by using the optimization method. The performances of the ejector and the hybrid system at different operating conditions were studied. Lastly, the performances of the ejector with fixed geometry and the corresponding hybrid system at off-design operating conditions were also theoretically studied. The results indicate that the optimum ejector mixing pressure is a little lower than the entrained fluid's pressure, but far larger than its critical pressure. No condensation shock happens before it flows into the diffuser. The theoretical performances of the hybrid compression refrigeration system with fixed geometry ejector at off-design conditions are very close to that with the optimum geometry ejector.
Xianlong Wang - One of the best experts on this subject based on the ideXlab platform.
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Performance characteristics of R1234yf ejector-expansion refrigeration cycle
Applied Energy, 2014Co-Authors: Huashan Li, Lingbao Wang, Xianbiao Bu, Xianlong WangAbstract:With a constant-pressure mixing ejector, the performance characteristics of an ejector-expansion refrigeration cycle (EERC) using R1234yf as refrigerant have been investigated. Also, the performance of R1234yf and R134a in the EERC has been compared. The study shows that, at condensing temperature of 40°C and evaporation temperature of 5°C, the coefficient of performance (COP) and volumetric cooling capacity (VCC) of the R1234yf EERC peak up to 5.91 and 2590.76kJ/m3, respectively. Compared with the standard refrigeration cycle the R1234yf EERC generally has a better performance, especially at the condition of higher condensing temperature and lower evaporation temperature. The COP and VCC improvements of the R1234yf EERC over the standard refrigeration cycle are also greater than that of the R134a cycle. In addition, the ejector design parameters including the pressure drop in Suction Nozzle, area ratio and component efficiencies on the R1234yf EERC performance have been analyzed.
