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Satha Aphornratana - One of the best experts on this subject based on the ideXlab platform.
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The performance of steam ejector refrigeration system based on alternative analysis
Energy Procedia, 2017Co-Authors: Borirak Kitrattana, Satha Aphornratana, Tongchana ThongtipAbstract:Abstract The performance of a steam ejector refrigerator was analyzed based on an “alternative analysis”. The alternative analysis reflects an actual operation of an ejector refrigerator. In this analysis, the evaporator saturation temperature associated with cooling load was varied while the boiler saturation temperature and the condenser pressure were fixed. Form this test, the critical evaporator temperature was determined. The critical evaporator temperature is the lowest point that ejector still operated under choked flow condition. A 1 kW experimental ejector refrigerator was constructed. Variation of operating conditions and Primary Nozzles were implemented. It was found that the variation in operating conditions and the Nozzle throat diameters significantly affected the critical evaporator temperature. Variation of condenser pressure had a strong effect on critical evaporator temperature Meanwhile the entrainment ratio in the choked flow condition was independent of the condenser pressure. The critical evaporator temperature decreased with increasing the condenser pressure and vice versa. Variations of the boiler saturation temperature and the Primary Nozzle throat diameter affect the mass flow of Primary fluid. Either increasing the boiler saturation temperature or the Primary Nozzle throat diameter, the mass flow of Primary fluid increased. When the Primary fluid mass flow was increased, the critical evaporator temperature was reduced. On the other hand, entrainment ratio in the choked flow condition decreased. However, if the Primary fluid mass flow was increased to a certain value, evaporator temperature didn’t decrease as expected.
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An experimental analysis of the impact of Primary Nozzle geometries on the ejector performance used in R141b ejector refrigerator
Applied Thermal Engineering, 2017Co-Authors: Tongchana Thongtip, Satha AphornratanaAbstract:This paper gives an experimental discussion of the geometrical impact of the Primary Nozzle on the ejector performance in an R141b ejector refrigerator. Primary Nozzle area ratio is varied to observe its effect on the ejector performance. Six Primary Nozzles are investigated experimentally. Four of them (D2.4M2.5, D2.8M2.5, D3.2M2.5, and D3.6M2.5) are designed with different throat diameters, but they have an identical Nozzle area ratio. Two of them, D2.4M2.0 and D2.4M3.0, have an identical throat diameter, but they have different Nozzle area ratio, resulting in a different Nozzle exit Mach number. All Nozzles are tested with one fixed geometry ejector at various operating conditions. Variations of the Primary momentum caused by the change in Primary Nozzle throat and Nozzle exit Mach number on the ejector performance is observed and discussed. The purpose is to determine the optimal Primary Nozzle geometries at given operating conditions. It is found that using a bigger Nozzle throat, operated with lower generator temperature, is preferable. The Primary Nozzle exit Mach number should be as high as possible. It should also be designed to be consistent with the heat source’s temperature for implementing the Nozzle at the designed conditions. The Primary Nozzle exit diameter must be consistent with the mixing chamber used. Therefore, the minimum required generator temperature (Tgen-min) at various Nozzle exit Mach numbers and the largest possible Nozzle exit diameter for one particular ejector are provided for this present work.
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cfd simulation on the effect of Primary Nozzle geometries for a steam ejector in refrigeration cycle
International Journal of Thermal Sciences, 2013Co-Authors: Natthawut Ruangtrakoon, Satha Aphornratana, Tongchana Thongtip, Thanarath SriveerakulAbstract:Abstract In this study, the CFD technique was employed to investigate the effect of the Primary Nozzle geometries on the performance of an ejector used in the steam jet refrigeration cycle. In all cases, only one fixed-geometry mixing chamber together with eight different Primary Nozzles was investigated numerically using the commercial CFD package, FLUENT 6.3. The effects on the Primary fluid pressure, mass flow rate and Mach number were observed and analyzed. The Mach number contour lines were used to explain the mixing process occurring inside the ejector. It was found that shock's position of the mixed fluid and the expansion angle of the Primary fluid jet stream within the mixing chamber played a very important role in the ejector performance.
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cfd simulation on the effect of Primary Nozzle geometries for a steam ejector in refrigeration cycle
International Journal of Thermal Sciences, 2013Co-Authors: Natthawu Ruangtrakoo, Satha Aphornratana, Tongchana Thongtip, Thanarath SriveerakulAbstract:Abstract In this study, the CFD technique was employed to investigate the effect of the Primary Nozzle geometries on the performance of an ejector used in the steam jet refrigeration cycle. In all cases, only one fixed-geometry mixing chamber together with eight different Primary Nozzles was investigated numerically using the commercial CFD package, FLUENT 6.3. The effects on the Primary fluid pressure, mass flow rate and Mach number were observed and analyzed. The Mach number contour lines were used to explain the mixing process occurring inside the ejector. It was found that shock's position of the mixed fluid and the expansion angle of the Primary fluid jet stream within the mixing chamber played a very important role in the ejector performance.
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experimental studies of a steam jet refrigeration cycle effect of the Primary Nozzle geometries to system performance
Experimental Thermal and Fluid Science, 2011Co-Authors: Natthawut Ruangtrakoon, Satha Aphornratana, Thanarath SriveerakulAbstract:This paper describes an experimental investigation of a steam jet refrigeration. A 1 kW cooling capacity experimental refrigerator was constructed and tested. The system was tested with various operating temperatures and various Primary Nozzles. The boiler saturation temperature ranked from 110 to 150 °C. The evaporator temperature was fixed at 7.5 °C. Eight Primary Nozzles with difference geometries were used. Six Nozzles have throat diameters ranked from 1.4 to 2.6 mm with exit Mach number of 4.0. Two remained Nozzles have equal throat diameter of 1.4 mm but difference exit Mach number, 3.0 and 5.5. The experimental results show that the geometry of the Primary Nozzle has strong effects to the ejector performance and therefore the system COP.
Lei Wang - One of the best experts on this subject based on the ideXlab platform.
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optimization design of steam ejector Primary Nozzle for med tvc desalination system
Desalination, 2019Co-Authors: Kai Wang, Lei WangAbstract:Abstract The paper proposes a mathematical model and efficient optimization design method for ejector Primary Nozzle to deal with the coupled ejector configuration parameters. A Primary Nozzle of steam ejector for multi-effect distillation with thermal vapor compression (MED-TVC) desalination system based on the proposed method is devised and then the designed Nozzle ejector performance is numerically investigated under various conditions. The performance results show that at fixed Primary pressure, the entrainment ratio (ER) at critical mode and critical back pressure (CBP) increase almost linearly with the ascending secondary pressure and the individual linear regression empirical formula is attained, respectively. The normal shock position can serve as the indicator of the ER at critical mode and CBP. Altering the secondary or back pressure causes the axial movement of the normal shock wave within the ejector, changing the ejector performance. The proposed design method can improve the overall ejector efficiency by 14.41% compared with conventional methods.
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Simulation on the performance of ejector in a parallel hybrid ejector-based refrigerator-freezer cooling cycle
Energy Conversion and Management, 2017Co-Authors: Lei Wang, Xianbi Li, Ling WangAbstract:Abstract In this paper, the simulation is carried out to investigate the performance of ejector used in a parallel hybrid ejector-based refrigerator-freezer cooling cycle. The geometric parameters such as Primary Nozzle diameter, area ratio and constant-pressure mixing chamber length are studied firstly to achieve a good performance of the fixed area ratio ejector under a certain condition. Based on the obtained ejector geometry, an adjustable ejector with a spindle is used in the system to meet the requirements of variable cooling loads. The results show that the effect of blocking percentage of Primary Nozzle with a spindle on the ejector performance is considerable. Moreover, the adjustable ejector works well with relatively high entrainment ratio when the back pressure increment percentage as compared to the secondary flow pressure is no less than 16.15%.
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the influence of the area ratio on ejector efficiencies in the med tvc desalination system
Desalination, 2017Co-Authors: Jiapeng Liu, Lei Wang, Lei Jia, Xinli WangAbstract:Abstract In this paper, an axi-symmetric computational fluid dynamics (CFD) model is used to investigate the effect of the area ratio on ejector component efficiencies. The geometrical parameters and operating conditions are designed for thermal vapor compression (TVC) used in multi-effect distillation (MED) desalination system. By changing the Primary Nozzle throat diameter and ejector throat diameter, two groups of ejectors are tested under different operating conditions. The results show that the mixing efficiency plays a more important role in ejector performance than other efficiencies such as Primary Nozzle efficiency, suction efficiency and diffuser efficiency with the changing of the area ratio. The mixing efficiency can be improved as much as 200% by adjusting the area ratio, and the entrainment ratio is increased from 0.025 to 0.8. Finally empirical correlations are summarized to estimate ejector component efficiencies.
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Numerical study on optimization of ejector Primary Nozzle geometries.
International Journal of Refrigeration, 2017Co-Authors: Lei Wang, Jia Yan, Chen WangAbstract:Abstract In an ejector refrigeration system (ERS), ejector acts as a compressor but without using any moving parts. To some extent, ejector performances are subjected to Primary Nozzle's geometries with the action of shock waves. In this paper, CFD simulation was conducted to improve the ejector performance by varying the following ejector Primary Nozzle's geometries and surface roughness: two angles of convergent and divergent portion, three lengths and surface roughness of throat, convergent and divergent portion. The CFD model was validated with the test results of an ERS experimental rig with working fluid of R134a. The optimum geometric parameters and surface roughness of the Primary Nozzle were obtained with the CFD analysis. The simulation results revealed that the throat and divergent portion of the Primary Nozzle should be paid more attention when designing ejector since the entrainment ratio of the ejector is rather sensitive to the length and surface roughness of these two portions.
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Influences of area ratio and surface roughness on homogeneous condensation in ejector Primary Nozzle
Energy Conversion and Management, 2017Co-Authors: Chen Wang, Lei Wang, Tao Zou, Hailun ZhangAbstract:Abstract Homogeneous condensation inside the ejector has been ignored by numerous researchers. In this paper, the wet steam model was utilized to study the influences of Nozzle area ratio and surface roughness on homogeneous condensation in a Primary Nozzle. A substantial amount of latent heat is released during the homogeneous condensation process to increase static pressure and reduce Mach number. The increase of Nozzle area ratio reduces condensation intensity and lowers Nozzle pressure but increases liquid mass fraction. Furthermore, with the growth of surface roughness, the slightly increased dryness fraction is almost ineffective for alleviating erosion caused by tiny droplets; the slight decrease in mass flow rate will reduce ejector performance to some extent, while the sharp increase of entropy generation results in more energy wastes. Therefore, Nozzle area ratio and surface roughness should be carefully designed to alleviate potential condensation and enhance ejector performance at the same time.
Tongchana Thongtip - One of the best experts on this subject based on the ideXlab platform.
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The performance of steam ejector refrigeration system based on alternative analysis
Energy Procedia, 2017Co-Authors: Borirak Kitrattana, Satha Aphornratana, Tongchana ThongtipAbstract:Abstract The performance of a steam ejector refrigerator was analyzed based on an “alternative analysis”. The alternative analysis reflects an actual operation of an ejector refrigerator. In this analysis, the evaporator saturation temperature associated with cooling load was varied while the boiler saturation temperature and the condenser pressure were fixed. Form this test, the critical evaporator temperature was determined. The critical evaporator temperature is the lowest point that ejector still operated under choked flow condition. A 1 kW experimental ejector refrigerator was constructed. Variation of operating conditions and Primary Nozzles were implemented. It was found that the variation in operating conditions and the Nozzle throat diameters significantly affected the critical evaporator temperature. Variation of condenser pressure had a strong effect on critical evaporator temperature Meanwhile the entrainment ratio in the choked flow condition was independent of the condenser pressure. The critical evaporator temperature decreased with increasing the condenser pressure and vice versa. Variations of the boiler saturation temperature and the Primary Nozzle throat diameter affect the mass flow of Primary fluid. Either increasing the boiler saturation temperature or the Primary Nozzle throat diameter, the mass flow of Primary fluid increased. When the Primary fluid mass flow was increased, the critical evaporator temperature was reduced. On the other hand, entrainment ratio in the choked flow condition decreased. However, if the Primary fluid mass flow was increased to a certain value, evaporator temperature didn’t decrease as expected.
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An experimental analysis of the impact of Primary Nozzle geometries on the ejector performance used in R141b ejector refrigerator
Applied Thermal Engineering, 2017Co-Authors: Tongchana Thongtip, Satha AphornratanaAbstract:This paper gives an experimental discussion of the geometrical impact of the Primary Nozzle on the ejector performance in an R141b ejector refrigerator. Primary Nozzle area ratio is varied to observe its effect on the ejector performance. Six Primary Nozzles are investigated experimentally. Four of them (D2.4M2.5, D2.8M2.5, D3.2M2.5, and D3.6M2.5) are designed with different throat diameters, but they have an identical Nozzle area ratio. Two of them, D2.4M2.0 and D2.4M3.0, have an identical throat diameter, but they have different Nozzle area ratio, resulting in a different Nozzle exit Mach number. All Nozzles are tested with one fixed geometry ejector at various operating conditions. Variations of the Primary momentum caused by the change in Primary Nozzle throat and Nozzle exit Mach number on the ejector performance is observed and discussed. The purpose is to determine the optimal Primary Nozzle geometries at given operating conditions. It is found that using a bigger Nozzle throat, operated with lower generator temperature, is preferable. The Primary Nozzle exit Mach number should be as high as possible. It should also be designed to be consistent with the heat source’s temperature for implementing the Nozzle at the designed conditions. The Primary Nozzle exit diameter must be consistent with the mixing chamber used. Therefore, the minimum required generator temperature (Tgen-min) at various Nozzle exit Mach numbers and the largest possible Nozzle exit diameter for one particular ejector are provided for this present work.
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cfd simulation on the effect of Primary Nozzle geometries for a steam ejector in refrigeration cycle
International Journal of Thermal Sciences, 2013Co-Authors: Natthawut Ruangtrakoon, Satha Aphornratana, Tongchana Thongtip, Thanarath SriveerakulAbstract:Abstract In this study, the CFD technique was employed to investigate the effect of the Primary Nozzle geometries on the performance of an ejector used in the steam jet refrigeration cycle. In all cases, only one fixed-geometry mixing chamber together with eight different Primary Nozzles was investigated numerically using the commercial CFD package, FLUENT 6.3. The effects on the Primary fluid pressure, mass flow rate and Mach number were observed and analyzed. The Mach number contour lines were used to explain the mixing process occurring inside the ejector. It was found that shock's position of the mixed fluid and the expansion angle of the Primary fluid jet stream within the mixing chamber played a very important role in the ejector performance.
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cfd simulation on the effect of Primary Nozzle geometries for a steam ejector in refrigeration cycle
International Journal of Thermal Sciences, 2013Co-Authors: Natthawu Ruangtrakoo, Satha Aphornratana, Tongchana Thongtip, Thanarath SriveerakulAbstract:Abstract In this study, the CFD technique was employed to investigate the effect of the Primary Nozzle geometries on the performance of an ejector used in the steam jet refrigeration cycle. In all cases, only one fixed-geometry mixing chamber together with eight different Primary Nozzles was investigated numerically using the commercial CFD package, FLUENT 6.3. The effects on the Primary fluid pressure, mass flow rate and Mach number were observed and analyzed. The Mach number contour lines were used to explain the mixing process occurring inside the ejector. It was found that shock's position of the mixed fluid and the expansion angle of the Primary fluid jet stream within the mixing chamber played a very important role in the ejector performance.
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Experimental Investigation of Impact of Primary Nozzle Area Ratio on Performance of Ejector Refrigeration System via Alternative Testing Method
Applied Thermal Engineering, 1Co-Authors: Tongchana Thongtip, Satha AphornratanaAbstract:Abstract This paper proposes an experimental investigation to demonstrate the impact of the Primary Nozzle area ratios on the ejector performance in an R141b ejector refrigeration system. The experimental refrigerator was tested based on the alternative testing method in which the generator temperature and condenser pressure were held constant for particular test cases. Three Primary Nozzles were studied which had identical throat diameter but different Nozzle area ratios which produced different exit Mach numbers. Three Primary Nozzles were equipped with one mixing chamber with throat diameter of 9 mm. With the alternative testing method, two critical evaporator temperatures were found, the lower and upper critical evaporator temperatures. It was also found that the change in the Nozzle exit Mach number and the Primary fluid mass flow rate (using different generator temperatures) had significant impact on these two critical points which affected the entire ejector performance. The Primary fluid expansion coefficient (CPrimary), which is key to indicate the limited range of the working condition, was introduced. It indicates the expansion wave formation which has significant impact on two critical points. Hence, the proper value of CPrimary under various Primary Nozzle area ratios was determined for this present work.
Thanarath Sriveerakul - One of the best experts on this subject based on the ideXlab platform.
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cfd simulation on the effect of Primary Nozzle geometries for a steam ejector in refrigeration cycle
International Journal of Thermal Sciences, 2013Co-Authors: Natthawu Ruangtrakoo, Satha Aphornratana, Tongchana Thongtip, Thanarath SriveerakulAbstract:Abstract In this study, the CFD technique was employed to investigate the effect of the Primary Nozzle geometries on the performance of an ejector used in the steam jet refrigeration cycle. In all cases, only one fixed-geometry mixing chamber together with eight different Primary Nozzles was investigated numerically using the commercial CFD package, FLUENT 6.3. The effects on the Primary fluid pressure, mass flow rate and Mach number were observed and analyzed. The Mach number contour lines were used to explain the mixing process occurring inside the ejector. It was found that shock's position of the mixed fluid and the expansion angle of the Primary fluid jet stream within the mixing chamber played a very important role in the ejector performance.
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cfd simulation on the effect of Primary Nozzle geometries for a steam ejector in refrigeration cycle
International Journal of Thermal Sciences, 2013Co-Authors: Natthawut Ruangtrakoon, Satha Aphornratana, Tongchana Thongtip, Thanarath SriveerakulAbstract:Abstract In this study, the CFD technique was employed to investigate the effect of the Primary Nozzle geometries on the performance of an ejector used in the steam jet refrigeration cycle. In all cases, only one fixed-geometry mixing chamber together with eight different Primary Nozzles was investigated numerically using the commercial CFD package, FLUENT 6.3. The effects on the Primary fluid pressure, mass flow rate and Mach number were observed and analyzed. The Mach number contour lines were used to explain the mixing process occurring inside the ejector. It was found that shock's position of the mixed fluid and the expansion angle of the Primary fluid jet stream within the mixing chamber played a very important role in the ejector performance.
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experimental studies of a steam jet refrigeration cycle effect of the Primary Nozzle geometries to system performance
Experimental Thermal and Fluid Science, 2011Co-Authors: Natthawut Ruangtrakoon, Satha Aphornratana, Thanarath SriveerakulAbstract:This paper describes an experimental investigation of a steam jet refrigeration. A 1 kW cooling capacity experimental refrigerator was constructed and tested. The system was tested with various operating temperatures and various Primary Nozzles. The boiler saturation temperature ranked from 110 to 150 °C. The evaporator temperature was fixed at 7.5 °C. Eight Primary Nozzles with difference geometries were used. Six Nozzles have throat diameters ranked from 1.4 to 2.6 mm with exit Mach number of 4.0. Two remained Nozzles have equal throat diameter of 1.4 mm but difference exit Mach number, 3.0 and 5.5. The experimental results show that the geometry of the Primary Nozzle has strong effects to the ejector performance and therefore the system COP.
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A study of flow in an ejector equipped with variable throat area of the Primary Nozzle using CFD simulation
Engineering and Applied Science Research, 2010Co-Authors: Nat Suvarnakuta, Kraiwut Uthaikorn, Thanarath Sriveerakul, Satha AphornratanaAbstract:The aim of this research is to study a flow in an ejector equipped with variable throat area of thePrimary Nozzle. Using a CFD technique, flow phenomena, mixing structure and performance of the ejectorwere analyzed and explained. In this study, a 2D-axisymetric model was used. Realizable k-epsilon modelwas applied for a turbulence model. R141b was selected as a refrigerant fluid. Instead of changing the size ofthe throat diameter, variation of throat area of the Primary Nozzle was achieved by changing a wedgesposition. The wedges position or the needle tip position (NTP) is defined as a distance between a plane ofneedles tip and a plane of the Primary Nozzles throat. Results show that altering the needle tip position (NTP)affects the ejectors performance. For example, changing the NTP to 0, 5 and 10 mm., under the Primary fluidsaturated temperature of 100 sC and the secondary fluid saturated temperature of 5 sC, the entrainment ratiowas subjected to increased from 0.24 to 0.30, and 0.52, respectively. While its critical back pressure (CBP)trend to reduce from 120.1 kPa to 112.2 kPa and 84.5 kPa. The results of this study were verified with a CFDsimulation of a typical R141b ejector (Sriveerakul, 2008). A CFD simulation at 5 mm. of NTP presents a closestCFD result to the typical ejector (the ejector without a wedge).
Armando C Oliveira - One of the best experts on this subject based on the ideXlab platform.
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cfd study of a variable area ratio ejector using r600a and r152a refrigerants
International Journal of Refrigeration-revue Internationale Du Froid, 2013Co-Authors: Szabolcs Varga, Pedro S Lebre, Armando C OliveiraAbstract:Abstract In the present paper, the numerical results for two 1 kW cooling capacity ejectors with variable Primary Nozzle geometry are presented using R152a and R600a as working fluids. Working fluids were selected based on the criteria of low environmental impact and good performance in the range of operating conditions adequate for using solar thermal energy as Primary heat source. Variable area ratio was achieved by applying a movable spindle at the Primary Nozzle inlet. Numerical results clearly show that adjusting spindle position resulted in a significant improvement of the entrainment ratio compared to a fixed geometry ejector when the operating conditions were different from design values. This increase in ejector performance was as high as 177% for low condenser pressures. Diagrams are also presented for both refrigerants that can be used to find spindle positions that maximise ejector performance under variable operating conditions.
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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, Siddig Omer, Wei Zhang, 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, Siddig Omer, 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. Copyright The Author 2010. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com, Oxford University Press.