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Статті в журналах з теми "Vapor ejector refrigeration"
1
Sumeru, Kasni, Luga Martin, Farid Nasir Ani, Henry Nasution, and Farid Nasir Ani. "Energy Savings in Air Conditioning System Using Ejector: An Overview." Applied Mechanics and Materials 493 (January 2014): 93–98. http://dx.doi.org/10.4028/www.scientific.net/amm.493.93.
Повний текст джерелаАнотація:
There are two ejector configurations described in the present study: ejector refrigeration cycle and the ejector as an expansion device. The use of waste heat from the car engine and industry as a heat-driven energy for air conditioning system in automobile and building can save energy. Although the ejector refrigeration cycle has a low COP, the use of waste heat as a heat-driven energy incurs a lower operational cost compared with vapor compression refrigeration system. In addition, an ejector as an expansion device can be applied in the vapor compression refrigeration cycle to improve the performance system.
2
Yosaf, Salem, and Hasan Ozcan. "Effect of Ejector Location in Absorption Refrigeration Cycles Using Different Binary Working Fluids." International Journal of Air-Conditioning and Refrigeration 27, no. 01 (March 2019): 1950003. http://dx.doi.org/10.1142/s2010132519500032.
Повний текст джерелаАнотація:
In this study, three novel modifications of ejector-absorption refrigeration cycles (E-ARC) are investigated to evaluate the effect of ejector location on cycle performances. In the first modification (triple pressure level absorption refrigeration cycle TPL-ARC), the ejector is located at the evaporator inlet. In the second modification (double ejector absorption refrigeration cycle DE-ARC), two ejectors are used; one is located at the evaporator inlet and the other at the absorber inlet, which are coupled to each other. In the third modification (low pressure condenser absorption refrigeration cycle LPC-ARC), the steam ejector is installed at the downstream of the vapor generator discharging line. An additional flow splitter is integrated to the steam ejector outlet and part of the vapor is extracted and returned to the absorber at a pressure equal to the diffuser pressure. Effect of ejector location on thermodynamic performances are evaluated considering three different working fluids, namely ammonia–water solution (NH3–H2O), lithium bromide-water solution (H2O–LiBr), and lithium chloride–water solution (H2O–LiCl). Even though all three configurations enhance the conventional absorption refrigeration cycle (C-ARC) performances, the LPC-ARCs work at high temperature and improve the cycle performance. The TPL-ARC proves to improve the COP and exergy efficiency up to 9.14% and 7.61%, respectively, presenting the highest thermodynamic performance enhancement and lowest operating temperature.
3
Ouelhazi, I., Y. Ezzaalouni, and L. Kairouani. "Parametric analysis of a combined ejector-vapor compression refrigeration cycle." International Journal of Low-Carbon Technologies 15, no. 3 (June 15, 2020): 398–408. http://dx.doi.org/10.1093/ijlct/ctaa011.
Повний текст джерелаАнотація:
Abstract From the last few years, the use of efficient ejector in refrigeration systems has been paid a lot of attention. In this article a description of a refrigeration system that combines a basic vapor compression refrigeration cycle with an ejector cooling cycle is presented. A one-dimensional mathematical model is developed using the flow governing thermodynamic equations based on a constant area ejector flow model. The model includes effects of friction at the constant-area mixing chamber. The current model is based on the NIST-REFPROP database for refrigerant property calculations. The model has basically been used to determine the effect of the ejector geometry and operating conditions on the performance of the whole refrigeration system. The results show that the proposed model predicts ejector performance, entrainment ratio and the coefficient of performance of the system and their sensitivity to evaporating and generating temperature of the cascade refrigeration cycle. The simulated performance has been then compared with the available experimental data from the literature for validation.
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Huang, B. J., C. B. Jiang, and F. L. Hu. "Ejector Performance Characteristics and Design Analysis of Jet Refrigeration System." Journal of Engineering for Gas Turbines and Power 107, no. 3 (July 1, 1985): 792–802. http://dx.doi.org/10.1115/1.3239802.
Повний текст джерелаАнотація:
Ejector performance characteristics and design analysis of jet refrigeration systems were studied. It was shown that choking phenomena in the secondary vapor play a very important role in ejector performance. Ejector choking, which is usually associated with a hypothesized effective area for the secondary vapor in the mixing zone, takes place when the ejector is operating at a back pressure below the critical value. The effective areas analyzed from the experiment were shown not to be constant but to vary with operating conditions. A performance map was constructed from the experimental results to show the ejector performance characteristics and from which the design analysis of jet refrigeration systems was carried out. Several important features of jet refrigeration system design are summarized in the present paper. Further analyses were also made to show the performance characteristics of jet refrigeration systems operating at off-design conditions.
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Raza, Waseem, Gwang Soo Ko, and Youn Cheol Park. "A Study on the Combined Driven Refrigeration Cycle Using Ejector." International Journal of Air-Conditioning and Refrigeration 29, no. 01 (January 25, 2021): 2150004. http://dx.doi.org/10.1142/s2010132521500048.
Повний текст джерелаАнотація:
The rising need for thermal comfort has resulted in a rapid increase in refrigeration systems’ usage and, subsequently, the need for electricity for air-conditioning systems. The ejector system can be driven by a free or affordable low-temperature heat source such as waste heat as the primary source of energy instead of electricity. Heat-driven ejector refrigeration systems become a promising solution for reducing energy consumption to conventional compressor-based refrigeration technologies. An air-conditioning system that uses the ejector achieves better performance in terms of energy-saving. This paper presents a study on the combined driven refrigeration cycle based on ejectors to maximize cycle performance. The experimental setup is designed to determine the coefficient of performance (COP) with ejector nozzle sizes 1.8, 3.6, and 5.4[Formula: see text]mm, respectively. In this system, the R-134a refrigerant is considered as a working fluid. The results depict that the efficiency is higher than that of the conventional refrigeration method due to comparing the performance of the conventional refrigeration cycle and the combined driven refrigeration cycle. The modified cycle efficiency is better than the vapor compression cycle below 0∘C, which implies sustainability at low temperatures by using low-grade thermal energy. For the improvement of mechanical efficiency, proposed cycle can be easily used.
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Mukhtar, Hamza K., and Saud Ghani. "Hybrid Ejector-Absorption Refrigeration Systems: A Review." Energies 14, no. 20 (October 13, 2021): 6576. http://dx.doi.org/10.3390/en14206576.
Повний текст джерелаАнотація:
Absorption Refrigeration Systems (ARS) are potential alternatives to direct expansion (DX) refrigeration systems. This review focused on the incorporation of an ejector into absorption refrigeration cycles to constitute Hybrid Ejector-Absorption Refrigeration Systems (HEARS). The ejector adds several advantages to the absorption refrigeration systems depending on its location in the cycle. The two prevalent configurations of HEARS are Triple pressure level (TPL-HEARS), and Low Pressure Condenser (LPC-HEARS). Previous studies revealed the preference of the latter configuration as it allows lower circulation ratios, enhances the refrigeration effect, and could achieve a COP up to 1. Moreover, LPC configuration is suitable with single, double, and variable-effect absorption systems with a COP of above unity. In turn, the TPL-HEARS notably enhances the absorption process, particularly when a variable geometry ejector is utilized. This configuration could obtain a COP around 1.1, but only with high-density refrigerant vapor. Lately, to attain the advantages of both configurations, some studies investigated the viability of adding two ejectors to the cycle. This paper meticulously reviews investigations conducted on the emerging dual ejectors-absorption refrigeration technology. This paper reveals the general performance trend and the maximum attainable COP by each type of hybrid ejector-absorption refrigeration system. DEARS and Ejector-driven absorption refrigeration systems (ED-ARS) could achieve COP that ranges between 1.2 and 1.46. The use of a flash tank and a RHE is essential in NH3/H2O HEARS. At high generator temperatures (of 120–170 °C), DEARS was found to be the system with less complexity and best performance. Nevertheless, the performance of the DEARS might drop significantly if the heat source temperature is fluctuating. Thence, the variable-effect HEARS is considered the best alternative. The capability of HEARS to be integrated with different power generation cycles is also highlighted. Finally, the review presents possible future research opportunities to improve the absorption refrigeration technology.
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Mukhtar, Hamza K., and Saud Ghani. "Hybrid Ejector-Absorption Refrigeration Systems: A Review." Energies 14, no. 20 (October 13, 2021): 6576. http://dx.doi.org/10.3390/en14206576.
Повний текст джерелаАнотація:
Absorption Refrigeration Systems (ARS) are potential alternatives to direct expansion (DX) refrigeration systems. This review focused on the incorporation of an ejector into absorption refrigeration cycles to constitute Hybrid Ejector-Absorption Refrigeration Systems (HEARS). The ejector adds several advantages to the absorption refrigeration systems depending on its location in the cycle. The two prevalent configurations of HEARS are Triple pressure level (TPL-HEARS), and Low Pressure Condenser (LPC-HEARS). Previous studies revealed the preference of the latter configuration as it allows lower circulation ratios, enhances the refrigeration effect, and could achieve a COP up to 1. Moreover, LPC configuration is suitable with single, double, and variable-effect absorption systems with a COP of above unity. In turn, the TPL-HEARS notably enhances the absorption process, particularly when a variable geometry ejector is utilized. This configuration could obtain a COP around 1.1, but only with high-density refrigerant vapor. Lately, to attain the advantages of both configurations, some studies investigated the viability of adding two ejectors to the cycle. This paper meticulously reviews investigations conducted on the emerging dual ejectors-absorption refrigeration technology. This paper reveals the general performance trend and the maximum attainable COP by each type of hybrid ejector-absorption refrigeration system. DEARS and Ejector-driven absorption refrigeration systems (ED-ARS) could achieve COP that ranges between 1.2 and 1.46. The use of a flash tank and a RHE is essential in NH3/H2O HEARS. At high generator temperatures (of 120–170 °C), DEARS was found to be the system with less complexity and best performance. Nevertheless, the performance of the DEARS might drop significantly if the heat source temperature is fluctuating. Thence, the variable-effect HEARS is considered the best alternative. The capability of HEARS to be integrated with different power generation cycles is also highlighted. Finally, the review presents possible future research opportunities to improve the absorption refrigeration technology.
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LITTLE, ADRIENNE B., and SRINIVAS GARIMELLA. "A REVIEW OF EJECTOR TECHNOLOGY FOR REFRIGERATION APPLICATIONS." International Journal of Air-Conditioning and Refrigeration 19, no. 01 (March 2011): 1–15. http://dx.doi.org/10.1142/s2010132511000351.
Повний текст джерелаАнотація:
This paper provides a comprehensive review of ejector technology for refrigeration applications, combining an understanding of basic fluid flow fundamentals within the ejector with application in cycle-level development. An ejector is a passive device that requires no external mechanical input or moving parts. A high-velocity motive stream produces a low-pressure region into which a suction flow is entrained, resulting in a pressure rise of the suction flow and mixing between the two streams to provide a pumping effect. The first part of this review addresses the progression from experiment-based analytical models to computational modeling of the ejector itself from the early 1950s to 2009. Included is an assessment of the most recent work in CFD modeling, and an exploration into what is needed to develop these models further. Suggestions for future research include better modeling of shock phenomena and the effects of two-phase flow in ejectors. The second part of this review focuses on ejector applications in refrigeration cycles with special emphasis on the vapor-jet refrigeration cycle. Important connections are made between ejector component and system level studies, an understanding of which would enable improvement of system level performance to the extent where they could be used in some niche applications instead of conventional refrigeration systems.
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Коновалов, Дмитро Вікторович, Роман Миколайович Радченко, Сергій Георгійович Фордуй, Фелікс Володимирович Царан, Віктор Павлович Халдобін та Артем Вікторович Грич. "Моделювання та програмний комплекс для дослідження функціонування ежектора в змінних режимах". RADIOELECTRONIC AND COMPUTER SYSTEMS, № 3 (5 жовтня 2021): 37–47. http://dx.doi.org/10.32620/reks.2021.3.04.
Повний текст джерелаАнотація:
One of the current directions of development of modern energy-saving and energy-efficient technologies for ship and stationery (including municipal) energy is the use of ejector refrigeration machines, which can be used for air conditioning systems together with an absorption refrigeration machine (cascade cycle) or vapor compressor refrigeration machine as part of cogeneration or trigeneration units. Such circuit solutions can be used together with ensuring the rational organization of work processes in the main elements of the refrigeration machine, in particular in the jet device - ejector, the appropriate design of which, in turn, will further increase the thermal coefficient. Improving the design of the ejector is a rather complex and long process and does not always give positive results. It is primarily because many tests are required on full-scale models. Therefore, computer simulation of the ejector operation at different variable input parameters, considering the geometric characteristics of the flow part and variable mode characteristics during operation is more attractive in terms of finding options for rational (optimal) design. The paper presents the results of software development for modeling hydrodynamic processes in the flowing part of the ejector, considering the variable operating modes of the ejector refrigeration machine. The existing method for calculating the pressure and circulation characteristics of jet devices is used. The developed software complex "RefJet" in the design mode defines the maximum achievable coefficients of ejection of a jet ejector. In the simulation mode - provides determination of the ejection coefficients of the already designed (certain sizes) ejector at variable values of pressure at the inlet and outlet in specific operating conditions, considering its operation at the limit and partial modes. The work of the software package was tested in the development and analysis of circuit solutions of ejector refrigeration machines as part of the heat recovery circuits of three-generation units based on internal combustion engines and gas turbine engines.
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JIAUTHEEN, PARVEEN BANU, and MANI ANNAMALAI. "REVIEW ON EJECTOR OF VAPOR JET REFRIGERATION SYSTEM." International Journal of Air-Conditioning and Refrigeration 22, no. 03 (September 2014): 1430003. http://dx.doi.org/10.1142/s2010132514300031.
Повний текст джерелаАнотація:
Vapor Jet Refrigeration (VJR) system is attractive among various heat operated refrigeration systems, because it has the potential of utilizing low grade thermal energy with source temperature as low as 60°C, which could be harnessed from renewable energy, waste heat, automobile-exhaust, etc. Also absence of moving parts in this system resulted in lesser maintenance costs. In addition to that this system causes very low environmental pollution due to almost negligible consumption of high grade energy from fossil fuels for running a small liquid pump of the system. Although VJR was invented very long back, still performance improvement to compete with vapor compression refrigeration system is in progress. Plenty of research has been carried out in different aspects for enhancing the efficiency of this technology. The present work/paper gives an overview of VJR system and its progression in the aspect of performance improvement. The developmental progress of the VJR technology presented in this paper has been categorized into the following groups, namely (a) general performance of an ejector, (b) numerical analysis, viz., classical one-dimensional analysis and Computational Fluid Dynamics (CFD) analysis, (c) experimental studies, (d) flow visualization studies, (e) performance enhancement techniques, and (f) two-phase ejector. And also presented a glimpse of some of the review papers from literature on VJR system.
Дисертації з теми "Vapor ejector refrigeration"
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Chen, Jianyong. "Investigation of Vapor Ejectors in Heat Driven Ejector Refrigeration Systems." Doctoral thesis, KTH, Tillämpad termodynamik och kylteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-156070.
Повний текст джерелаАнотація:
Refrigeration systems, air-conditioning units and heat pumps have been recognized as indispensable machines in human life, and are used for e.g. food storage, provision of thermal comfort. These machines are dominated by the vapor compression refrigeration system and consume a large percentage of world-wide electricity output. Moreover, CO2 emissions related to the heating and cooling processes contribute significantly to the total amount of CO2 emission from energy use. The ejector refrigeration system (ERS) has been considered as a quite interesting system that can be driven by sustainable and renewable thermal energy, like solar energy, and low-grade waste heat, consequently, reducing the electricity use. The system has some other remarkable merits, such as being simple and reliable, having low initial and running cost with long lifetime, and providing the possibility of using environmentally-friendly refrigerants, which make it very attractive. The ERS has received extensive attention theoretically and experimentally. This thesis describes in-depth investigations of vapor ejectors in the ERS to discover more details. An ejector model is proposed to determine the system performance and obtain the required area ratio of the ejector by introducing three ejector efficiencies. Based on this ejector model, the characteristics of the vapor ejector and the ERS are investigated from different perspectives. The working fluid significantly influences the ejector behavior and system performance as well as the ejector design. No perfect working fluid that satisfies all the criteria of the ERS can be found. The performance of nine refrigerants has been parametrically compared in the ERS. Based on the slope of the vapor saturation curve in a T-s diagram, the working fluids can be divided into three categories: wet, dry and isentropic. A wet fluid has a negative slope of the vapor saturation curve in the T-s diagram. An isentropic expansion process from a saturated vapor state will make the state after the expansion to fall inside the liquid-vapor area of the T-s diagram which will result in droplet formation. Generally, an isentropic expansion for a dry fluid will not occur inside the liquid-vapor area, and consequently no droplets will form. An isentropic fluid has a vertical slope of the vapor saturation curve in the T-s diagram and an isentropic expansion process will hence follow the vapor saturation curve in the T-s diagram, ideally without any droplet formation. However, when the saturation condition is close to the critical point, it is possible that the isentropic expansion process of a dry fluid and an isentropic fluid occurs inside the liquid-vapor area of the T-s diagram, resulting in formation of droplets. In order to avoid droplet formation during the expansion, a minimum required superheat of the primary flow has been introduced before the nozzle inlet. Results show that the dry fluids have generally better performance than the wet fluids and the isentropic fluid. Hence the thesis mostly focuses on the features of vapor ejectors and the ERS using dry fluids. Exergy analysis has been proven to be very useful to identify the location, magnitude, and sources of exergy destruction and exergy loss, and to determine the possibilities of system performance improvement. This method is applied to the ejector and the ERS. The ejector parameters are closely interacting. The operating condition and the ejector area ratio have a great impact on the ejector overall efficiency and system COP. The ejector efficiencies are sensitive to the operating conditions, and they significantly influence the system performance. A so-called advanced exergy analysis is adopted to quantify the interactions among the ERS components and to evaluate the realistic potential of improvement. The results indicate that, at the studied operating condition, the ejector should have the highest priority to be improved, followed by the condenser, and then the generator. Thermoeconomics, which combines the thermodynamic analysis and economic principles, is applied to reveal new terms of interest of the ERS. The economic costs of the brine side fluids (fluids that supply heat to the generator and evaporator and remove heat from the condenser) play very essential roles in the thermoeconomic optimization of the ERS. Depending on different economic conditions, the system improvement from a thermodynamic point of view could be quite different from the thermoeconomic optimization. The ERS is economically sound when using free heat sources and heat sink. An ejector test bench has been built to test the entrainment ratio of different ejectors. Although the experiments do not achieve the desired results, they could still be discussed. The insignificant effect of the superheat of the secondary flow found in the theoretical study is validated. The assumption of neglecting the velocities at the ejector inlets and outlet are confirmed. The quantification of the ejector efficiencies shows that they largely depend on the operating conditions and the ejector dimensions.QC 20141102
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FEHLING, SIMON. "CO2 Refrigeration withIntegrated Ejectors : Modelling and Field Data Analysis ofTwo Ice Rinks and Two Supermarket Systems." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-299502.
Повний текст джерелаАнотація:
With the increasing importance of CO2 as natural refrigerant with low Global Warming Potential(GWP) ejectors have been used in a number of recent installations to recover expansion work atthe high operating pressures of these systems. In colder climates, this is particularly seen in combinationwith heat recovery due to the high compressor discharge pressures.This work analyses the field measurement data of two ice rink refrigeration systems with integratedvapor ejectors and two supermarket refrigeration systems with integrated liquid ejectors, alllocated in northern Europe. The aim is to evaluate the interaction of the ejector with the refrigerationsystem in practical applications. A theoretical model of the ejector systems is developed andevaluated in parallel as a reference for the analysed system installations.The model of the analysed vapor ejector system shows an increasing eciency improvement potentialby the ejector for higher gas cooler outlet temperatures, while the liquid ejector systemmodel indicates higher eciency improvement potential at relatively lower gas cooler outlet temperaturesand pressures.From the vapor ejector field data evaluation, this is confirmed with additional findings of lowejector work recovery eciencies at low gas cooler outlet temperatures. Furthermore, problemsin the ejector operation are found for too low evaporation temperatures in one of the systems. Inaddition, an unstable ejector control at certain operating conditions is linked to a decreasing ejectorperformance. While the ejector is found not to provide any significant savings in one of the systemsmainly due to low evaporation temperatures, the other ice rink system is found to achievetotal energy savings of 7% from the ejector.For the liquid ejector field data evaluation, the ejectors are found to work as expected for the purposeof removing liquid from the low-pressure receiver. However, overfed evaporation conditionsare only found temporarily for most cabinets in the analysed systems, with remaining high averagesuperheat values. Low required air supply temperatures in the cabinets and the dimensioning of theexpansion valves at the evaporator inlet are identified as possible limitations for a further decreaseof the superheat and increase of the evaporation temperature.Med den ökande betydelsen av CO2 som naturligt köldmedium med låg global uppvärmningspotential(GWP) har ejektorer använts i ett antal nya installationer för att återvinna expansionsarbetevid de höga drifttrycken i dessa system. I kallare klimat är detta särskilt vanligt i kombination medvärmeåtervinning på grund av de höga utloppstrycken i kompressorerna.I detta arbete analyseras fältmätdata från två kylsystem för isbanor med integrerade ångejektoreroch två kylsystem för livsmedelsbutiker med integrerade vätskeejektorer. Samtliga system finns inorra Europa. Syftet med studien är att utvärdera ejektorns samverkan med kylsystemet i praktiskatillämpningar. En teoretisk modell av ejektorsystemen utvecklas och utvärderas parallellt som referensför de analyserade systeminstallationerna.Modellen för det analyserade ångejektorsystemet visar att potentialen för e ektivitetsförbättringgenom ejektorn ökar vid högre utloppstemperaturer för gaskylare, medan modellen försystemet med vätskeutkastare visar att potentialen för e ektivitetsförbättring ökar vid relativt lägreutloppstemperaturer och tryck för gaskylare.Detta bekräftas i utvärderingen av fältdata från ångejektorsystemen som vid låga utloppstemperatureri gaskylaren samtidigt ger låg e ektivitet för ejektorn. Dessutom noteras problemmed ejektorns funktion vid för låga förångningstemperaturer i ett av systemen. En instabilstyrning av ejektorn vid vissa driftsförhållanden leder vidare till en minskad ejektore ektivitet.Medan ejektorn inte ger några betydande besparingar i det ena systemet, främst på grund av lågaavdunstningstemperaturer, har en total energibesparing på 7% från ejektorn hittats i den andra isbanan.När det gäller utvärderingen av fältdata för vätskeejektorer konstateras att ejektorerna fungerar somförväntat för att avlägsna vätska från vätskeavskiljaren. För de flesta kyldiskar i de analyseradesystemen syns dock bara kortvarigt flödad tillstånd i förångrarna, och i övrigt en kvarvarande höggenomsnittlig överhettning. Låg erforderlig tilluftstemperatur i kyldiskarna och dimensioneringenav expansionsventilerna vid förångarens inlopp identifieras som möjliga begränsningar för enytterligare minskning av överhettningen och en ökning av förångningstemperaturen.
Тези доповідей конференцій з теми "Vapor ejector refrigeration"
1
Abuan, Binoe E., and Menandro S. Berana. "Ejector Profile Modelling for Heat-Driven Ejector Refrigeration System Without Involving Shock." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-52521.
Повний текст джерелаАнотація:
Heat-driven ejector refrigeration system is one of the fastest emerging technologies in cooling applications for years. This is due to the fact that it can harness cooling capacity from waste heat sources at above 80 °C. Low coefficient of performance (compared to commercial vapor compression systems) is the major disadvantage of the said system, and thus it became a topic of research studies in the field of cooling. The work required by the compressor in a vapor compression cycle (VCC) can be eliminated by using waste heat from any available heat source. Although a relatively lower COP was obtained, the savings using the ejector refrigeration system can cover all the disadvantages and proved that this system can be actually helpful if implemented in the real working systems with waste heat. In this study, a mathematical model for determining ejector parameters and performance was developed and applied to a system where shock was tried to be avoided. The model was coded into a computer program to allow easier computation of the ejector geometric and thermo-fluid dynamic parameters with varying input data such as the refrigerant to be used, evaporator and condensing temperatures, entrainment ratio, and velocity of the fluid flows. An ejector refrigeration system using ammonia, propane, R22, R134a, R1234yf, and R245fa as refrigerants was simulated using the said model. A boiler or generator temperature of 90 °C, a condenser temperature of 40 °C, and a refrigerating capacity of 35kW were maintained for all the refrigerants; however, the evaporator temperature was varied within the range of −10 °C to 10 °C, depending on the behavior of the system. A combination of a short straight section and then a converging-diverging profile was used for the combined mixing section and diffuser to smoothly decelerate the fully mixed supersonic flow exiting the short mixing section and thereby avoid shock waves in the section. The resulting parameters including the ejector dimensions, pressure and Mach number were determined along the length of the ejector. For all the simulation runs, the fluids respond as expected and the expansion energy was utilized from the high pressure side of the ejector as shown in the trend of pressure along the length of the ejector. Ejector size varies a little for different refrigerants; the calculated range of length is from 0.14 m to 0.36 m — this range shows the compactness of the resulting ejectors. The results show that a VCC refrigeration system can be replaced by a heat-driven ejector refrigeration system with the ejector that was designed from the simulations. Since the two systems are designed to have the same refrigerating capacity and working temperatures, it can be projected that savings can be made by using the ejector system. The compactness of the ejector produced in the simulations show a good potential for this kind of refrigerating system to be manufactured and mass produced.
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Jayachandran, Sankrish, and T. Sundararajan. "Performance Analysis of an Ejector-Diffuser for Vapor Jet Refrigeration." In 9th International Conference on Fluid Flow, Heat and Mass Transfer (FFHMT'22). Avestia Publishing, 2022. http://dx.doi.org/10.11159/ffhmt22.154.
Повний текст джерела
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Su, Liju, Ramesh K. Agarwal, and Subhodeep Banerjee. "CFD Simulation of a Supersonic Steam Ejector for Refrigeration Application." In ASME/JSME/KSME 2015 Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ajkfluids2015-3125.
Повний текст джерелаАнотація:
Supersonic steam ejectors are widely used in many industrial applications, for example for refrigeration and desalination. The experimental evaluation of the flow field inside the ejector is relatively difficult and costly due to the occurrence of shock after the velocity of the steam reaches over the sonic level in the ejector. In this paper, numerical simulations are conducted to investigate the detailed flow field inside a supersonic steam (water vapor being the working fluid) ejector. The commercial computational fluid dynamics (CFD) flow solver ANSYS-Fluent and the mesh generation software ANSYS-ICEM are used to predict the steam performance during the mixing inside the ejector by employing two turbulence models, the k-ω SST and the k-ε realizable models. The computed results are validated against the experimental data. The effects of operating conditions on the efficiency of the ejector such as the primary fluid pressure and condenser pressure are studied to obtain a better understanding of the mixing process and entrainment. Velocity contours, pressure plots and shock region analyses provide a good understanding for optimization of the ejector performance, in particular how to increase the entrainment ratio.
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Su, Liju, and Ramesh K. Agarwal. "CFD Simulation of a Supersonic Steam Ejector for Refrigeration Application." In ASME 2016 Fluids Engineering Division Summer Meeting collocated with the ASME 2016 Heat Transfer Summer Conference and the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/fedsm2016-7614.
Повний текст джерелаАнотація:
Supersonic steam ejectors are widely used in many industrial applications, for example for refrigeration and desalination. The experimental evaluation of the flow field inside the ejector is relatively difficult and costly due to the occurrence of shock after the velocity of the steam reaches over the sonic level in the ejector. In this paper, numerical simulations are conducted to investigate the detailed flow field inside a supersonic steam (water vapor being the working fluid) ejector. The commercial computational fluid dynamics (CFD) flow solver ANSYS-Fluent and the mesh generation software ANSYS-ICEM are used to predict the steam performance during the mixing inside the ejector by employing two turbulence models, the k-ω SST and the k-ε realizable models. The computed results are validated against the experimental data. The effects of operating conditions on the efficiency of the ejector such as the primary fluid pressure and condenser pressure are studied to obtain a better understanding of the mixing process and entrainment. Velocity contours, pressure plots and shock region analyses provide a good understanding for optimization of the ejector performance, in particular how to increase the entrainment ratio.
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Wang, Yuping, Mark Pellerin, Pravansu Mohanty, and Subrata Sengupta. "Numerical and Experimental Study of Flow Phenomenon Inside Gas Ejectors With Moist Gases Entrainment." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-53480.
Повний текст джерелаАнотація:
Gas ejectors can be found in a wide range of applications such as refrigeration and thrust augmentation. This paper focuses on the study of an ejector used in applications where moist gases are being entrained. In the first part of this work, the gas flow characteristics inside an ejector, as well as the ejector’s performance under various operating and geometric configurations, were studied with a three-dimensional computational model, which was validated against measurement data. In the second part, focus was given to the potential condensation or de-sublimation phenomena that may occur inside an ejector when water vapor is included in the entrained stream. An experiment using light-attenuation method was performed to verify the presence of a second phase, then the onset of phase change and the phase distribution were obtained numerically. A two-dimensional axis-symmetric model was developed based on the model used in the first part. A series of simulations were performed with various amounts of water vapor added into the entrained flow. It was found that both frost particles and water condensate could form inside the mixing tube depending on the operating conditions and water vapor concentrations. When the concentration exceeds 3%, water vapor could condense throughout the mixing tube. Some preliminary results of the second phase particles formed, e.g. critical sizes and distributions, were also obtained to assist with the design and optimization of gas ejectors used in similar applications.
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Zhang, Bo, Jianhua Dong, and Shengqiang Shen. "Mathematical Simulation of a Solar Bi-Ejector Refrigeration System." In ASME 2006 International Solar Energy Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/isec2006-99058.
Повний текст джерелаАнотація:
This paper presents a mathematical simulation of the dynamic thermal behavior of an innovative solar bi-ejector refrigeration system with a capacity to produce cooling water. In the bi-ejector refrigeration system, the mechanical circulation pump is replaced by a vapor-liquid ejector, in order to further reduce the electricity consumption and reinforce the system feasibility. Freon R123 is the working fluid at condensing temperature of 30°C generating temperature of 85°C and evaporating temperature of 8°C The generator heat load is 10kW and an obtained evaporator cooling load is around 3kW. The whole year simulation results are presented.
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Chiriac, Victor, and Florin Chiriac. "The Miniaturization of a Refrigeration Vapor Compression System and Application to the Cooling of High Power Microelectronics." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14537.
Повний текст джерелаАнотація:
The study develops an analytical model of an optimized small scale refrigeration system using ejector vapor compression, with application to the cooling of the electronic components populating a Printed Circuit Board (PCB) in a High-Power Microelectronics System. The authors' previous studies [1 - 3] evaluated a vapor compression system using an off-the-shelf mechanical compressor and associated components, focusing mainly on the thermal feasibility of the mechanical refrigeration system and on-chip system-level incorporation. Present investigation focuses on the miniaturization of the various components of the vapor compression system (targeting the alternative ejector vapor compressor), with the intent to establish a cooling system for high power microelectronics, designed to fit smaller packages populating PCB, yet using a different approach for the vapor compression process. The previous study [1] evaluated several optimized evaporator designs for the mechanical compression system. The current design with miniaturized ejector is evaluated to address similar power dissipation ranges as before. In the final section of the study, the efficiency of the proposed ejector vapor compression system is compared to mechanical compression designs at same cooling powers. It is the intent of the authors to present an alternative vapor compression system and identify the pros and cons of implementing such a system to real-life microelectronics applications.
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Tavakol, Mohsen, and Maziar Shafaee. "CFD Study on Supersonic Ejectors Used for Suction of Two Different Gases." In ASME 2015 9th International Conference on Energy Sustainability collocated with the ASME 2015 Power Conference, the ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2015 Nuclear Forum. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/es2015-49577.
Повний текст джерелаАнотація:
In ejector refrigeration cycles, ejector working fluids include various refrigerants with different properties. In some cases, ejector works with mixture of two different refrigerants; that each refrigerant have distinct properties. The purpose of this paper is to evaluate the performance of an ejector used for suction of a mixture of air and water vapor. In this regard, the ejector performance was numerically studied under the operating condition that a mixture of air and steam with variable mass fractions, were sucked into the ejector. With the help of numerical simulation, various conditions for two perfect gas streams of air and water vapor were investigated. Initially, the numerical simulation was carried out for the case that pure water vapor was considered as the working fluid of ejector. After validation of initial case with experimental data, numerical method was expanded for a specific case that, water vapor was considered as the working fluid of motive flow and a mixture of air and water vapor was considered for suction flow. Numerical simulations were done for different mass fraction of air and water vapor for suction flow mixture. Results indicated that, variations of the mass fraction of air in suction flow, leads to obvious changes in ejector performance. Also, it was observed that the increment of suction flow pressure, leads to increment of the ejector performance sensitivity to variations of suction flow mass fraction.
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Zhang, TieJun, Saleh Mohamed, and Guanqiu Li. "Fundamental Considerations for Designing Compact Solar Thermal Power and Ejector Cooling Systems in Hot Climates." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-65928.
Повний текст джерелаАнотація:
A combined thermal power and ejector refrigeration cooling cycle is proposed in this paper to harness low-grade solar energy. It utilizes abundant and low-cost hydrocarbon as the working fluid. Hydrocarbon has been identified as a promising alternative to existing high global-warming-potential refrigerants (i.e., HFC refrigerant R134a) in next-generation refrigeration systems. Several typical alternative refrigerants are evaluated by considering their fundamental thermophysical properties: absolute pressure level, volumetric cooling capacity, surface tension, saturated liquid/vapor density ratio and kinematic viscosity. Comparing with R1234yf, R1234ze and R744 (CO2), hydrocarbon refrigerants, such as R290 (propane) and R601 (pentane), do have inherent advantages for either cooling or power generation purposes in hot climates: lower flow resistance and better heat transfer at higher temperature. Fundamental phase stability and transition issues have been considered in designing pentane vapor ejectors for combined power and cooling cycles operating at high ambient temperature. Thermodynamic analysis has indicated that the proposed solar thermal system can provide an effective way to sustainable energy production in hot and dry climates.
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Shahamiri, S. Ali, M. Mehdi Salek, Wayne May, and Robert J. Martinuzzi. "Application of Binary Fluid Ejector in Thermal Vapor Compression Distillation Systems." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-88745.
Повний текст джерелаАнотація:
Ejector Refrigeration Systems (ERS) offer the use of low grade energy sources. These systems are simple in principle; however, suffer from relatively low COP, mainly due to inefficient energy exchange between the primary and secondary fluid flows in the ejector. The use of two chemically distinct fluids in forward and reversed Rankine cycles of such systems has been shown to improve COP. These systems are known as Binary Fluid ERS (BFERS). This paper focuses on the application of BFERS for the purpose of water distillation. First, a model for an ideal ejector was developed and the maximum theoretical COP of the system was determined. Actual COP of the system was also estimated by computing the entrainment ratio in the ejector using computational fluid dynamic modeling (CFD). The effects of certain fluid properties such as molecular masse and specific heat ratio of the two fluids were investigated with respect to mass entrainment ratio. A number of guidelines for the selection of suitable primary and secondary fluids were developed based on research literature and the potential for increasing COP through the use of chemically distinct fluids, i.e. binary operating fluids.