The Experts below are selected from a list of 1038 Experts worldwide ranked by ideXlab platform
Satha Aphornratana - One of the best experts on this subject based on the ideXlab platform.
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design of Steam Ejector in a refrigeration application based on thermodynamic performance analysis
Sustainable Energy Technologies and Assessments, 2019Co-Authors: Natthawut Ruangtrakoon, Satha AphornratanaAbstract:Abstract This paper presents a theoretical calculation method for designing the Steam Ejectors for refrigeration applications. The working fluid is assumed to be an ideal gas. The flow processes inside the Ejector are analyzed by using thermodynamic and ideal gas equations. The advantage of this paper is that the presentation of the theory and calculation procedure are very easy to understand and follow. A design criterion of a Steam Ejector is also provided. The experimental results at several operating conditions are used to validate the theoretical results. The validation results show that this calculation method can be used as an efficient tool in the design of Steam Ejectors.
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comparison of traditional and crmc Ejector performance used in a Steam Ejector refrigeration
Energy Procedia, 2017Co-Authors: Borirak Kitrattana, Satha Aphornratana, Tongchana Thongtip, Natthawut RuangtrakoonAbstract:Abstract In this paper, performance of a Steam Ejector designed based on the constant rate of momentum change (CRMC) and traditional Ejector were tested in an attempt to compare its performance. Three different Ejectors were designed and constructed; traditional Ejector with throat diameter of 19 mm, traditional Ejector with throat diameter of 13.4 mm, and CRMC Ejector with throat diameter of 13.4 mm. They were designed to be easily equipped with the 1kW experimental Ejector refrigerator. The boiler saturation pressure was varied from 130°C to 140°. The evaporator saturation temperature were fixed at 7.5°C. The result show that at the same operating condition and the same Ejector area ratio (the area ratio of nozzle throat to Ejector throat), CRMC Ejector provided higher entrainment ratio than the traditional Ejectors while the critical condenser pressure remain the same.
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development and performance of Steam Ejector refrigeration system operated in real application in thailand
International Journal of Refrigeration-revue Internationale Du Froid, 2014Co-Authors: Natthawut Ruangtrakoon, Satha AphornratanaAbstract:Abstract This paper presents the design and construction of a prototype Steam Ejector refrigeration system which can be operated under the actual condition of Thai environment, which is rather hot and humid. The prototype refrigerator was designed to produce a cooling capacity of approximately 3 kW. Water was selected to be used as the working fluid. The Steam boiler used was a vertical fire tube type and it was designed to be used with LPG compact gas burner. The condenser was cooled by water obtained from a conventional cooling tower. The prototype refrigerator was used to produce chilled water which was used to cool a small tested room. It was observed that the room temperature of 24.2 °C was obtained at the cooling load of 3000 W. The cooling water was supplied to the condenser at about 30 °C. The COP obtained was 0.45. This prototype refrigerator is proven to be practical and can be used in actual environment of Thailand.
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theoretical study of a Steam Ejector refrigerator
International Energy Journal, 2007Co-Authors: Satha AphornratanaAbstract:This paper provides a theoretical analysis of a seam-Ejector. An Ejector model is developed based on one-dimensional ideal gas theory which was first introduced by Keenan. This theory is modified to include losses associated with the primary nozzle, mixing chamber, and diffuser. This Ejector model is then used to analyse thermodynamic performance of a Steam Ejector refrigeration cycle over a range of operating temperatures. The theoretical results are compared with the experimental results obtained from the literatures.
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performance prediction of Steam Ejector using computational fluid dynamics part 2 flow structure of a Steam Ejector influenced by operating pressures and geometries
International Journal of Thermal Sciences, 2007Co-Authors: T Sriveerakul, Satha Aphornratana, K ChunnanondAbstract:The aim of this study is to reveal the complication of the flow and the mixing process of a Steam Ejector used in a jet refrigeration cycle by using the simulation software package (FLUENT). In Part 1 of this work, the CFD results of the Steam Ejector's performance were validated with the experimental values. After the validation is satisfied, this paper is able to analyze the flow phenomena inside the Steam Ejector when its operating conditions and geometries were varied. Using the applications provided by the CFD software, the flow structure of the modeled Ejectors could be created graphically, and the phenomena inside the flow passage were explored. The CFD method was evaluated as an efficient tool to represent the flow inside a Steam Ejector.
Szabolcs Varga - One of the best experts on this subject based on the ideXlab platform.
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a cfd analysis of the flow structure inside a Steam Ejector to identify the suitable experimental operating conditions for a solar driven refrigeration system
International Journal of Refrigeration-revue Internationale Du Froid, 2014Co-Authors: Chiheb Bouden, Yosr Allouche, Szabolcs VargaAbstract:Abstract This paper presents a numerical study of a Steam Ejector using CFD with the objective of identifying suitable experimental conditions that allows for a reliable Ejector cycle operation. The flow structure and the mixing process inside the Ejector were assessed for a range of operating conditions typical for a solar driven air conditioning system. The effect of varying the condenser pressure was studied. It was found that for relatively low condenser pressures (
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experimental and numerical analysis of a variable area ratio Steam Ejector
International Journal of Refrigeration-revue Internationale Du Froid, 2011Co-Authors: Szabolcs Varga, Armando C. Oliveira, Wei Zhang, Siddig Omer, Saffa B. RiffatAbstract:Abstract In the present paper, experimental and CFD results for a 5 kW capacity Steam Ejector with variable primary nozzle geometry are presented and compared. The variable geometry was achieved by applying a movable spindle at the primary nozzle inlet. Operating conditions were considered in a range that would be suitable for an air-conditioning application, with thermal energy supplied by vacuum tube solar collectors. The CFD model was based on the axi-symmetric representation of the experimental Ejector, using water as working fluid. The experimental entrainment ratio varied in the range of 0.1–0.5 depending on operating conditions and spindle tip position. It was found that the primary flow rate can be successfully adjusted by the spindle. CFD and experimental primary flow rates agreed well, with an average relative error of 7.7%. CFD predicted the secondary flow rate and entrainment ratio with good accuracy only in 70% of the cases.
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comparison of cfd and experimental performance results of a variable area ratio Steam Ejector
International Journal of Low-carbon Technologies, 2011Co-Authors: Szabolcs Varga, Armando C. Oliveira, Wei Zhang, Siddig Omer, Saffa B. RiffatAbstract:The advantages of numerical modelling compared with experimental studies (e.g. reduced cost, easy control of the variables, high yield etc.) are well known. Theoretical studies where experimental validation is also presented provide an important added value to numerical investigations. In the present paper, experimental and computational fluid dynamics (CFD) results for a 5-kW-rated capacity Steam Ejector, with a variable primary nozzle geometry, are presented and compared. The variable geometry was achieved by applying a movable spindle at the primary nozzle inlet. Relatively low operating temperatures and pressures were considered, so that the cooling system could be operated with thermal energy supplied by solar collectors (solar air-conditioning). The CFD model was based on the axi-symmetric representation of the experimental Ejector, using water as a working fluid. The experimental entrainment ratio varied in the range of 0.1--0.5, depending on operating conditions and spindle tip position. It was found that the primary flow rate can be successfully adjusted by the spindle. CFD and experimental primary flow rates agreed well, with an average relative error of 8%. CFD predicted the secondary flow rate and entrainment ratio with good accuracy only in 70% of the cases. Copyright The Author 2010. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com, Oxford University Press.
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Experimental and numerical analysis of a variable area ratio Steam Ejector
International Journal of Refrigeration, 2011Co-Authors: Szabolcs Varga, S A Omer, Xiaoli Ma, Armando C. Oliveira, Wei Zhang, Saffa B. RiffatAbstract:In the present paper, experimental and CFD results for a 5 kW capacity Steam Ejector with variable primary nozzle geometry are presented and compared. The variable geometry was achieved by applying a movable spindle at the primary nozzle inlet. Operating conditions were considered in a range that would be suitable for an air-conditioning application, with thermal energy supplied by vacuum tube solar collectors. The CFD model was based on the axi-symmetric representation of the experimental Ejector, using water as working fluid. The experimental entrainment ratio varied in the range of 0.1-0.5 depending on operating conditions and spindle tip position. It was found that the primary flow rate can be successfully adjusted by the spindle. CFD and experimental primary flow rates agreed well, with an average relative error of 7.7%. CFD predicted the secondary flow rate and entrainment ratio with good accuracy only in 70% of the cases. ?? 2010 Elsevier Ltd and IIR. All rights reserved.
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Comparison of CFD and experimental performance results of a variable area ratio Steam Ejector
International Journal of Low-Carbon Technologies, 2011Co-Authors: Szabolcs Varga, S A Omer, Xiaoli Ma, Armando C. Oliveira, Wei Zhang, Saffa B. RiffatAbstract:The advantages of numerical modelling compared with experimental studies (e.g. reduced cost, easy control of the variables, high yield etc.) are well known. Theoretical studies where experimental validation is also presented provide an important added value to numerical investigations. In the present paper, experimental and computational fluid dynamics (CFD) results for a 5-kW-rated capacity Steam Ejector, with a variable primary nozzle geometry, are presented and compared. The variable geometry was achieved by applying a movable spindle at the primary nozzle inlet. Relatively low operating temperatures and pressures were considered, so that the cooling system could be operated with thermal energy supplied by solar collectors (solar air-conditioning). The CFD model was based on the axi-symmetric representation of the experimental Ejector, using water as a working fluid. The experimental entrainment ratio varied in the range of 0.1–0.5, depending on operating conditions and spindle tip position. It was found that the primary flow rate can be successfully adjusted by the spindle. CFD and experimental primary flow rates agreed well, with an average relative error of 8%. CFD predicted the secondary flow rate and entrainment ratio with good accuracy only in 70% of the cases.
Jingming Dong - One of the best experts on this subject based on the ideXlab platform.
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numerical investigation on the influence of mixing chamber length on Steam Ejector performance
Applied Thermal Engineering, 2020Co-Authors: Jingming Dong, Qiuyu Hu, Mengqi Yu, Daliong LiangAbstract:Abstract A Steam Ejector can effectively utilize waste heat resources, which is widely used in the fields of air conditioning, refrigeration, and seawater desalination. The structure of the Steam Ejector’s mixing chamber has a critical influence on its performance. In this paper, the effects of the mixing chamber length on the Steam Ejector performance under different Mach numbers at the nozzle exit, constant area section length, and diffuser length are studied using three-dimensional (3D) numerical simulations. The numerical simulation results show that the entrainment ratio and critical back pressure of the Steam Ejector rise first and then decrease with the increasing of the mixing chamber length under different Mach numbers, constant area section lengths and diffuser lengths. The Steam Ejector can achieve a better performance with the mixing chamber length in the range of 40–80 mm, when the nozzle throat diameter is 2.5 mm under a typical working condition of Steam Ejector refrigeration.
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Experimental Investigation of the Steam Ejector in a Single-Effect Thermal Vapor Compression Desalination System Driven by a Low-Temperature Heat Source
Energies, 2018Co-Authors: Jingming Dong, Yangbo Deng, Weining Wang, Hongbin Ma, Fengmin SuAbstract:The paper presents an experimental investigation of a Steam Ejector in a single-effect thermal vapor compression (S-TVC) desalination system driven by a low-temperature (below 100 °C) heat source. To investigate the performance of the Steam Ejector in the S-TVC desalination system, an experimental Steam Ejector system was designed and built. The influences of the nozzle exit position (NXP), operating temperatures, and the area ratio of the Ejector (AR) on the Steam Ejector performance were investigated at primary Steam temperatures ranging from 40 °C to 70 °C, and at secondary Steam temperatures ranging from 10 °C to 25 °C. The experimental results showed that the Steam Ejector can work well in the S-TVC desalination system driven by a low-temperature heat source below 100 °C. The Steam Ejector could achieve a higher coefficient of performance (COP) by decreasing the primary Steam temperature, increasing the secondary Steam temperature, and increasing the AR. The Steam Ejector could also be operated at a higher critical condensation temperature by increasing the primary Steam temperature and secondary Steam temperature, and decreasing the AR. This study will allow S-TVC desalination to compete with adsorption desalination (AD).
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experimental investigation on low temperature thermal energy driven Steam Ejector refrigeration system for cooling application
Applied Thermal Engineering, 2017Co-Authors: Weining Wang, Jingming Dong, Mengqi Yu, He Song, Celue LiAbstract:Abstract In recent years, Ejector refrigeration has been a hot topic for research because it can utilize low-grade energy such as solar energy or industrial waste heat. Even more importantly, it uses the most environmentally friendly substance, water, as the working fluid. According to the literatures, the utilization of the thermal energy from a low-temperature heat source below 80 °C is a considerable challenge for the Steam Ejector refrigeration system. In this paper, an experimental prototype of the Steam Ejector refrigeration system was designed and built up. Three Ejectors with a same nozzle for the primary nozzle and three different constant-area sections were designed and fabricated. The effects of the operating temperatures, the nozzle exit position (NXP) and the area ratio of the Ejector ( AR ) on the working performance of the Steam Ejector were investigated. The generating temperature is ranged from 40 °C to 70 °C. The experimental results show that a Steam Ejector can operate successfully for a certain configuration size of the Steam Ejector with a generating temperature ranging from 40 °C to 70 °C and an evaporating temperature of 15 °C. The results of this investigation provided a better understanding for the cooling application of the Steam Ejector refrigeration system powered by low-temperature heat source. It demonstrates that the Steam Ejector refrigeration system is a very promising alternative to the absorption refrigeration system, when the heat source temperature is lower than 80 °C.
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An experimental investigation of Steam Ejector refrigeration system powered by extra low temperature heat source
International Communications in Heat and Mass Transfer, 2017Co-Authors: Jingming Dong, Chunlu Kang, Weining Wang, Xuli Chen, Hongbin MaAbstract:A Steam Ejector refrigeration system is a low capital cost solution for utilizing industrial waste heat or solar energy. When the heat source temperature is lower than 80 °C, the utilization of the thermal energy from such a low-temperature heat source can be a considerable challenge. In this investigation, an experimental prototype for the Steam Ejector refrigeration system was designed and manufactured, which can operate using extra low-temperature heat source below 80 °C. The effects of the operation temperature, the nozzle exit position (NXP) and the diameter of the constant area section on the working performance of the Steam Ejector were investigated at generating temperatures ranging from 40 °C to 70 °C. Three Ejectors with a same de Laval nozzle for the primary nozzle and three different constant-area sections were designed and fabricated. The experimental results show that a Steam Ejector can function for a certain configuration size of the Steam Ejector with a generating temperature ranging from 40 °C to 70 °C and an evaporating temperature of 10 °C. For a given NXP, the system COP and cooling capacity of the Steam Ejector decreased until inoperative as the diameter of the constant area section reduced. The results of this investigation provided a good solution for the refrigeration application of the Steam Ejector refrigeration system powered by an extra low-temperature heat source.
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Experimental Investigation of Steam Ejector System With an Extra Low Generating Temperature
Journal of Thermal Science and Engineering Applications, 2016Co-Authors: Jingming Dong, C. L. Kang, H. M. Wang, Hongbin MaAbstract:A Steam Ejector system is environmentally friendly but limited to utilizing thermal energy with a temperature typically ranging from 100 °C to 200 °C. As the Steam generating temperature decreases, the utilization of the thermal energy from such a low-temperature heat source becomes very challenging. In this investigation, an experimental Steam Ejector system was designed and constructed to investigate the performance of the Ejector system with water as the working fluid at Steam generating temperatures ranging from 40 °C to 60 °C. A convergent nozzle and a de Laval nozzle were used in the Steam Ejector as the primary nozzles, respectively. The experimental results show that the Steam Ejector at a generating temperature ranging from 40 °C to 60 °C can function. The performance of the convergent nozzle is a little better than that of the de Laval nozzle in most cases at the given working condition. For power plant or desalination system applications, the system coefficient of performance (COP) of the Ejector with convergent nozzle could reach 3.06 when the Steam generating temperature is 40 °C and the evaporator temperature is 25 °C. For refrigeration application, the Ejector with a de Laval nozzle can achieve a system COP of 0.21 and 0.4 at a generating temperature of 60 °C. The results of this investigation enabled a better understanding of system performance characteristics in a Steam Ejector system at a generating temperature below 100 °C.
Yanxia Li - One of the best experts on this subject based on the ideXlab platform.
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visualization experimental study of the condensing flow regime in the transonic mixing process of desalination oriented Steam Ejector
Energy Conversion and Management, 2019Co-Authors: Yongzhi Tang, Yanxia Li, Hongqiang Wu, Xiaopeng Zhang, Nan YangAbstract:Abstract There are few available related studies about condensing flow regime in the transonic mixing process of Steam Ejector due to its extreme complexity, although it is of great importance for improving Ejector entrainment performance and broadening its application. In this paper, a visualization experimental platform of desalination-oriented Steam Ejector is designed, and the condensing flow regimes under various entrainment pressures pH are captured from multiple perspectives, by means of direct photography approach. The results reveal that the supersonic jet flow is full with massive amounts of condensation droplets whose particle size distribution is not uniform at various vertical positions, and some easily lose their dynamic equilibrium. There exists a slant reverse condensing flow cross-section at the mixing chamber end, which moves upstream as pH rises and where great numbers of condensation droplets constantly generate around. The condensate quantity of each observation surface is different and increases with pH. The reverse condensing flow regime formed is very complex and accompanied by flexible swirls, clockwise circumferential flow and condensate dynamic accumulation. Then the generated condensate significantly reduces after multiple evaporations downstream the reverse cross-section. It is also found that the flow regime is similar at a same field of view, but diverse at the different fields of view. These meaningful results could serve as a good start point for reducing internal irreversible losses and tailoring Ejector design, as well as refining and evaluating physical and mathematical two-phase flow Ejector models.
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a combined pressure regulation technology with multi optimization of the entrainment passage for performance improvement of the Steam Ejector in med tvc desalination system
Energy, 2019Co-Authors: Yongzhi Tang, Yanxia Li, Chen LvAbstract:Abstract Steam Ejector as an energy-saving unit is of critical importance to the overall performance of MED-TVC desalination system. In this study, a combined pressure regulation solution is proposed to dredge the blocked entrained flow and alleviate the high-pressure effect simultaneously for multiple optimization of the entrainment passage flow field. The systematic analysis and investigation mainly concentrate on the feasibility verifications of the combined pressure regulations, and the performance comparisons between the combined and single pressure regulation schemes under various operating conditions. The results reveal that the throat-combined pressure regulation would simply lose efficacy, the diffuser- and multi-combined pressure regulations could achieve a similar multiple optimization that the alleviation effectiveness remains almost steady and the dredging effectiveness enhances continually as the back pressure decreases. Moreover, there is an optimum combination among the pressure regulation schemes, by which a most significant entrainment ratio improvement could be achieved, as high as 28.75% in the present simulations covered range. To be specific, TMCE pressure regulation could be selected if the Ejector operates under the design condition, and for the off-design conditions, multi-combined pressure regulation should be adopted if the back pressure not exceeds its critical value, otherwise, CMCE pressure regulation is the best choice.
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numerical study for the influences of primary Steam nozzle distance and mixing chamber throat diameter on Steam Ejector performance
International Journal of Thermal Sciences, 2018Co-Authors: Weina Fu, Yanxia Li, Hongqiang Wu, Yongzhi TangAbstract:Abstract The geometry and operation parameters have important influences on the performance of Steam Ejectors. An axisymmetric two-dimensional mathematical model for transonic compressible flow inside a Steam Ejector has been established in this paper to investigate the flow characteristics inside Steam Ejectors aiming at optimizing primary Steam nozzle exit section distance and mixing chamber throat diameter simultaneously. The results show that there are an optimum value for the primary Steam nozzle distance ratio and an optimum diameter ratio of mixing chamber throat to primary nozzle throat at which the Steam Ejector acquires its best entrainment performance under the given design conditions. With the optimized primary Steam nozzle distance, the optimization of the diameter ratio of the mixing chamber throat to primary nozzle throat is significant. In our case, the improvement of the entrainment ratio is as large as 25%. Deviation from its optimized value may result in a serious degeneration in the Ejector performance. Therefore, to ensure the Steam Ejector performance, the primary Steam nozzle distance should be designed at its optimum value and the diameter ratio of the mixing chamber throat to primary nozzle throat be within a narrow vicinity of its optimum value.
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a novel Steam Ejector with pressure regulation to dredge the blocked entrained flow for performance improvement in med tvc desalination system
Energy Conversion and Management, 2018Co-Authors: Yongzhi Tang, Yanxia LiAbstract:Abstract Steam Ejectors are regarded as a promising energy-saving technology, it is thus crucial to enhance its working performance for broader application horizons. In this study, a detailed simulation is made of a design Steam Ejector used in MED-TVC desalination system. The results discloses that there is actually a large entrained flow blocked region downstream the entraining entrance and significant low-pressure potentials inside the throat and diffuser whose pressure are far lower than that of the blocked region. Based on this finding, a so-called pressure regulation technology is proposed to use these existing pressure differences to dredge the blocked entrained flow, and thus more entrained Steam could be drawn into the Ejector. Then the feasibility verifications of different pressure regulation schemes are carried out, and a systematic analysis and investigation of their influences on the entrainment performance has been implemented systematically from the mass flow rate and pressure field. The results reveal that there is an optimum combination of pressure regulation schemes to dredge the blocked entrained flow effectively, by which a maximum and considerable entrainment ratio improvement could be achieved, as large as 26.85% in the covered simulations, and with 3.31% even under the design condition. To be specific, the throat-entraining entrance downstream pressure regulation should be adopted if the Ejector operates under the design condition, otherwise, the combined-entraining entrance downstream pressure regulation is the best choice.
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a novel Steam Ejector with pressure regulation to optimize the entrained flow passage for performance improvement in med tvc desalination system
Energy, 2018Co-Authors: Yongzhi Tang, Yanxia LiAbstract:Abstract Steam Ejector plays a critical role in MED-TVC desalination system that can achieve a good balance between freshwater production and energy savings. In this study, a pressure regulation technology is proposed to optimize the entrained flow passage and thus improve the Ejector performance. The theoretical basis is that there have some existing low-pressure potentials inside the Ejector that can be used to alleviate the high-pressure effect and shock wave at the mixing chamber end. Then the feasibility verification and performance comparison of different pressure regulation schemes is implemented systematically. Analysis and research mainly pay attention to the influences of pressure regulations on the mass flow rate, the entrainment ratio and internal flow field. The results reveal that there is an optimum combination of pressure regulation schemes, by which a most considerable entrainment ratio improvement could be achieved, as large as 11.77% within the simulated conditions, and with 3.94% even under the design condition. More specifically, for the given Steam Ejector, TMCE pressure regulation could be used if the Ejector operates under the design condition. For the off-design conditions, CMCE pressure regulation is the best choice if the back pressure is larger than 34 kPa, otherwise DMCE pressure regulation should be chosen.
Saffa B. Riffat - One of the best experts on this subject based on the ideXlab platform.
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experimental and numerical analysis of a variable area ratio Steam Ejector
International Journal of Refrigeration-revue Internationale Du Froid, 2011Co-Authors: Szabolcs Varga, Armando C. Oliveira, Wei Zhang, Siddig Omer, Saffa B. RiffatAbstract:Abstract In the present paper, experimental and CFD results for a 5 kW capacity Steam Ejector with variable primary nozzle geometry are presented and compared. The variable geometry was achieved by applying a movable spindle at the primary nozzle inlet. Operating conditions were considered in a range that would be suitable for an air-conditioning application, with thermal energy supplied by vacuum tube solar collectors. The CFD model was based on the axi-symmetric representation of the experimental Ejector, using water as working fluid. The experimental entrainment ratio varied in the range of 0.1–0.5 depending on operating conditions and spindle tip position. It was found that the primary flow rate can be successfully adjusted by the spindle. CFD and experimental primary flow rates agreed well, with an average relative error of 7.7%. CFD predicted the secondary flow rate and entrainment ratio with good accuracy only in 70% of the cases.
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comparison of cfd and experimental performance results of a variable area ratio Steam Ejector
International Journal of Low-carbon Technologies, 2011Co-Authors: Szabolcs Varga, Armando C. Oliveira, Wei Zhang, Siddig Omer, Saffa B. RiffatAbstract:The advantages of numerical modelling compared with experimental studies (e.g. reduced cost, easy control of the variables, high yield etc.) are well known. Theoretical studies where experimental validation is also presented provide an important added value to numerical investigations. In the present paper, experimental and computational fluid dynamics (CFD) results for a 5-kW-rated capacity Steam Ejector, with a variable primary nozzle geometry, are presented and compared. The variable geometry was achieved by applying a movable spindle at the primary nozzle inlet. Relatively low operating temperatures and pressures were considered, so that the cooling system could be operated with thermal energy supplied by solar collectors (solar air-conditioning). The CFD model was based on the axi-symmetric representation of the experimental Ejector, using water as a working fluid. The experimental entrainment ratio varied in the range of 0.1--0.5, depending on operating conditions and spindle tip position. It was found that the primary flow rate can be successfully adjusted by the spindle. CFD and experimental primary flow rates agreed well, with an average relative error of 8%. CFD predicted the secondary flow rate and entrainment ratio with good accuracy only in 70% of the cases. Copyright The Author 2010. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com, Oxford University Press.
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Experimental and numerical analysis of a variable area ratio Steam Ejector
International Journal of Refrigeration, 2011Co-Authors: Szabolcs Varga, S A Omer, Xiaoli Ma, Armando C. Oliveira, Wei Zhang, Saffa B. RiffatAbstract:In the present paper, experimental and CFD results for a 5 kW capacity Steam Ejector with variable primary nozzle geometry are presented and compared. The variable geometry was achieved by applying a movable spindle at the primary nozzle inlet. Operating conditions were considered in a range that would be suitable for an air-conditioning application, with thermal energy supplied by vacuum tube solar collectors. The CFD model was based on the axi-symmetric representation of the experimental Ejector, using water as working fluid. The experimental entrainment ratio varied in the range of 0.1-0.5 depending on operating conditions and spindle tip position. It was found that the primary flow rate can be successfully adjusted by the spindle. CFD and experimental primary flow rates agreed well, with an average relative error of 7.7%. CFD predicted the secondary flow rate and entrainment ratio with good accuracy only in 70% of the cases. ?? 2010 Elsevier Ltd and IIR. All rights reserved.
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Comparison of CFD and experimental performance results of a variable area ratio Steam Ejector
International Journal of Low-Carbon Technologies, 2011Co-Authors: Szabolcs Varga, S A Omer, Xiaoli Ma, Armando C. Oliveira, Wei Zhang, Saffa B. RiffatAbstract:The advantages of numerical modelling compared with experimental studies (e.g. reduced cost, easy control of the variables, high yield etc.) are well known. Theoretical studies where experimental validation is also presented provide an important added value to numerical investigations. In the present paper, experimental and computational fluid dynamics (CFD) results for a 5-kW-rated capacity Steam Ejector, with a variable primary nozzle geometry, are presented and compared. The variable geometry was achieved by applying a movable spindle at the primary nozzle inlet. Relatively low operating temperatures and pressures were considered, so that the cooling system could be operated with thermal energy supplied by solar collectors (solar air-conditioning). The CFD model was based on the axi-symmetric representation of the experimental Ejector, using water as a working fluid. The experimental entrainment ratio varied in the range of 0.1–0.5, depending on operating conditions and spindle tip position. It was found that the primary flow rate can be successfully adjusted by the spindle. CFD and experimental primary flow rates agreed well, with an average relative error of 8%. CFD predicted the secondary flow rate and entrainment ratio with good accuracy only in 70% of the cases.