Articles de revues : « Ejector refrigeration »

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Mukhtar, Hamza K., et Saud Ghani. « Hybrid Ejector-Absorption Refrigeration Systems : A Review ». Energies 14, n^o 20 (13 octobre 2021) : 6576. http://dx.doi.org/10.3390/en14206576.

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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., et Saud Ghani. « Hybrid Ejector-Absorption Refrigeration Systems : A Review ». Energies 14, n^o 20 (13 octobre 2021) : 6576. http://dx.doi.org/10.3390/en14206576.

Texte intégral

Résumé :

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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OLARU, IONEL. « A FLUID FLOW ANALYSIS OF A JET EJECTOR SYSTEM USED IN INDUSTRIAL APPLICATIONS ». Journal of Engineering Studies and Research 26, n^o 3 (27 juillet 2020) : 143–47. http://dx.doi.org/10.29081/jesr.v26i3.217.

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Many studies have been conducted for jet ejectors used in the recovery of solar energy or for their use in refrigeration systems for various industrial applications. Generally, these types of ejectors are using water as the working fluid because water have a low cost, a chemical stability and is safe to use. Naturally, other refrigerants, with large-scale application for industry, can be used. In such a type of jet ejector, besides selection of the refrigerant, the design of ejector is very important, with strongly influence to the performance, because the compression ratio depends on the geometry of the nozzle and on the geometry of the diffuser. Compared to other refrigeration systems, those with ejector have some advantages: simplicity in construction, high liability and low cost. However, it has a coefficient of performance lower than conventional systems, this limited the widespread application of ejector refrigeration systems.

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Ben Zid, Nihel, Nejib Hajji et Mohamed El Ganaoui. « COP enhancement and comparison of different absorption cooling systems ». MATEC Web of Conferences 330 (2020) : 01032. http://dx.doi.org/10.1051/matecconf/202033001032.

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The absorption refrigeration machines represent a good alternative to compression refrigeration machines but the major problem of this type of refrigeration lies in the COP, which seems to be less efficient. Several researches are carried out to improve the performances of these machines such as the combination with the technology of the ejectors. In this work, we are interested in the three ammonia-water absorption cycles: Single effect absorption, Ejector-absorption and Combined ejector-flash tank absorption cycles. A gas-gas ejector would be installed between the generator and the condenser. We suppose that adding a flash tank between the condenser and the evaporator could help improve the entrainment ratio of the ejector. We used simulations in order to compare the performances of these three different cycles. The simulation results demonstrate that the combined ejector-flash tank absorption cycle performs better than others.

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Yosaf, Salem, et Hasan Ozcan. « Effect of Ejector Location in Absorption Refrigeration Cycles Using Different Binary Working Fluids ». International Journal of Air-Conditioning and Refrigeration 27, n^o 01 (mars 2019) : 1950003. http://dx.doi.org/10.1142/s2010132519500032.

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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.

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Abdellaoui, Ezzaalouni Yathreb, et Lakdar Kairouani Kairouani. « Thermodynamic analysis of a new dual evaporator CO2 transcritical refrigeration cycle ». Archives of Thermodynamics 38, n^o 1 (28 mars 2017) : 39–62. http://dx.doi.org/10.1515/aoter-2017-0003.

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AbstractIn this work, a new dual-evaporator CO2transcritical refrigeration cycle with two ejectors is proposed. In this new system, we proposed to recover the lost energy of condensation coming off the gas cooler and operate the refrigeration cycle ejector free and enhance the system performance and obtain dual-temperature refrigeration simultaneously. The effects of some key parameters on the thermodynamic performance of the modified cycle are theoretically investigated based on energetic and exergetic analysis. The simulation results for the modified cycle indicate more effective system performance improvement than the single ejector in the CO2vapor compression cycle using ejector as an expander ranging up to 46%. The exergetic analysis for this system is made. The performance characteristics of the proposed cycle show its promise in dual-evaporator refrigeration system.

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Raza, Waseem, Gwang Soo Ko et Youn Cheol Park. « A Study on the Combined Driven Refrigeration Cycle Using Ejector ». International Journal of Air-Conditioning and Refrigeration 29, n^o 01 (25 janvier 2021) : 2150004. http://dx.doi.org/10.1142/s2010132521500048.

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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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Коновалов, Дмитро Вікторович, Роман Миколайович Радченко, Сергій Георгійович Фордуй, Фелікс Володимирович Царан, Віктор Павлович Халдобін et Артем Вікторович Грич. « Моделювання та програмний комплекс для дослідження функціонування ежектора в змінних режимах ». RADIOELECTRONIC AND COMPUTER SYSTEMS, n^o 3 (5 octobre 2021) : 37–47. http://dx.doi.org/10.32620/reks.2021.3.04.

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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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Haida, Michal, Jacek Smolka, Michal Palacz, Jakub Bodys, Andrzej Nowak, Zbigniew Bulinski, Adam Fic, Krzysztof Banasiak et Armin Hafner. « Numerical investigation of an R744 liquid ejector for supermarket refrigeration systems ». Thermal Science 20, n^o 4 (2016) : 1259–69. http://dx.doi.org/10.2298/tsci151210112h.

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This paper presents a numerical investigation of an R744 liquid ejector applied to a supermarket refrigeration system. The use of the liquid ejector enables the operation of the evaporator in a flooded mode and recirculates the R744 liquid phase, which improves the energy efficiency of the refrigeration system. The investigation was performed using two ejectors of different sizes installed in a multi-ejector block. The numerical model was formulated based on the homogenous equilibrium model and validated with the experimental results. The influence of the pre-mixer, mixer and diffuser dimensions on the ejector performance measured using the mass entrainment ratio is presented. The results show that the best liquid ejector performance was obtained for the short lengths of the pre-mixer and mixer compared to the broadly investigated two-phase ejectors connected to the evaporator port. In addition, wide diffuser angles improved the mass entrainment ratio of both liquid ejectors, which may lead to a reduction in the diffuser length.

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LITTLE, ADRIENNE B., et SRINIVAS GARIMELLA. « A REVIEW OF EJECTOR TECHNOLOGY FOR REFRIGERATION APPLICATIONS ». International Journal of Air-Conditioning and Refrigeration 19, n^o 01 (mars 2011) : 1–15. http://dx.doi.org/10.1142/s2010132511000351.

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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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Zheng, Lixing, Yiyan Zhang, Lifen Hao, Haojie Lian, Jianqiang Deng et Wei Lu. « Modelling, Optimization, and Experimental Studies of Refrigeration CO2 Ejectors : A Review ». Mathematics 10, n^o 22 (18 novembre 2022) : 4325. http://dx.doi.org/10.3390/math10224325.

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CO2 is regarded as an effective and environmentally friendly refrigerant. Using a CO2 ejector is a proven method for enhancing the effectiveness of a transcritical CO2 refrigerant system. However, the complex internal flow of a CO2 ejector, involving supersonic effects, phase change effects, metastable effects, and so on, makes it difficult to understand. In order to summarize the current state of the technology and knowledge gaps, this work provides a comprehensive literature review on CO2 ejectors. In the first part, mathematical modelling and simulation calculations of CO2 ejectors are presented, and an overview and classification of ejector models are given. In the second part, the structural optimization part of the ejector is described in detail, and the nozzle structure, the mixing chamber length, improvements to multi-jet systems, and the impact of these factors on the system performance are analyzed. In the third part, flow visualization is used to study the complex flow phenomenon, and the effect of the shock wave on the entrained rate of the ejector is discussed. Finally, the paper outlines the relationship between all ejector technologies, working fluids, and ejector performance and makes valid recommendations for further research and development of CO2 ejectors.

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Söylemez, Engin, Armin Hafner, Christian Schlemminger, Ekaterini E. Kriezi et Vahid Khorshidi. « The Performance Analysis of an Integrated CO2 Refrigeration System with Multi-Ejectors Installed in a Supermarket ». Energies 15, n^o 9 (25 avril 2022) : 3142. http://dx.doi.org/10.3390/en15093142.

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The field data from an integrated CO2 refrigeration system installed in a supermarket located north of the capital of Lisbon was analyzed. The goal was to demonstrate the effect and performance of multi-ejectors on a refrigeration system operating in a warm climate. The measurement results for the system with and without activating ejectors were compared. It was observed that the system with a multi-ejector operation had considerable performance superiority. The ejectors improved the cooling capacity of the medium temperature stage of the system by 17.4%. The system with active ejectors had 7.5% less total power consumption compared to the ejector off mode of the same system.

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Söylemez, Engin, Armin Hafner, Christian Schlemminger, Ekaterini E. Kriezi et Vahid Khorshidi. « The Performance Analysis of an Integrated CO2 Refrigeration System with Multi-Ejectors Installed in a Supermarket ». Energies 15, n^o 9 (25 avril 2022) : 3142. http://dx.doi.org/10.3390/en15093142.

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The field data from an integrated CO2 refrigeration system installed in a supermarket located north of the capital of Lisbon was analyzed. The goal was to demonstrate the effect and performance of multi-ejectors on a refrigeration system operating in a warm climate. The measurement results for the system with and without activating ejectors were compared. It was observed that the system with a multi-ejector operation had considerable performance superiority. The ejectors improved the cooling capacity of the medium temperature stage of the system by 17.4%. The system with active ejectors had 7.5% less total power consumption compared to the ejector off mode of the same system.

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Sumeru, Kasni, Luga Martin, Farid Nasir Ani, Henry Nasution et Farid Nasir Ani. « Energy Savings in Air Conditioning System Using Ejector : An Overview ». Applied Mechanics and Materials 493 (janvier 2014) : 93–98. http://dx.doi.org/10.4028/www.scientific.net/amm.493.93.

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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.

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Guangpeng, Li, Zhou Yingli et Wang Qi. « Application and analysis of carbon dioxide refrigeration system with ejector in commercial super cold cabinet ». E3S Web of Conferences 267 (2021) : 02019. http://dx.doi.org/10.1051/e3sconf/202126702019.

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In this paper, the transcritical CO2 refrigeration system with ejector is applied to a commercial ultra-cold cabinet. The influence of the key operating parameters of the ejector on the system performance is analyzed, and the measurement method of the experimental parameters is proposed. The results show that the ejector can eject the low pressure refrigerant into the reservoir by using the energy of the large pressure difference throttle, and the COP of the system can be increased by 9%-19%. This paper provides a theoretical basis for the design, development and optimization of CO2 refrigeration and air conditioning system with ejector.

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Besagni, Giorgio, et Fabio Inzoli. « The influence of Variable Geometry Control on a R290 Ejector Refrigeration System ». Journal of Physics : Conference Series 2177, n^o 1 (1 avril 2022) : 012010. http://dx.doi.org/10.1088/1742-6596/2177/1/012010.

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Abstract The large-scale deployment of ejector refrigeration systems (i.e., solar-based ejector refrigeration systems), although representing a promising alternative compared with mechanical compressor ones, is hindered due to limitations regarding ejector control modes. Indeed, ejectors are fluid-dynamics controlled devices and, because of their fixed geometry, they operate at their highest efficiency in a narrow range of operating conditions, which is in contrast with the dynamic pressure and temperature levels characterizing real applications. In this context, variable geometry ejectors (VGE) represent a promising solution to increase the flexibility and operation range of this component. The present study aims to extend the present body of knowledge regarding VGE systems, evaluating the impact of a spindle-provided ejector operated with R290 on the performance of the refrigeration system. The analysis has been carried out using an integrated lumped parameter/CFD approach, thus linking the local flow properties and global performances. Different spindle positions have been tested to assess how the different nozzle area ratios affect both the entrainment ratio and the critical pressure. Results showed that increasing primary nozzle area ratio the system can effectively reduce the thermal input, increasing the average COP at the expanse of a lower critical pressure. In conclusion, using a moving spindle control system might ensure an improvement of the ejector performance.

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Abdella Mohammed, Yahya Gaafar, Tawat Suriwong, Sakda Somkun et Timeyo Mkamanga Maroyi. « Exergy Analysis of a Solar-Driven Dual Parallel-Connected Ejector Refrigeration System ». Applied Mechanics and Materials 839 (juin 2016) : 100–106. http://dx.doi.org/10.4028/www.scientific.net/amm.839.100.

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Nowadays, developing solar cooling technologies, especially ejector refrigeration system, has become preferable to scientific researchers. Exergy analysis is a technique in which the basis of evaluation of thermodynamic losses follows the second law rather than the first law of thermodynamics. An experimental exergy analysis of a solar-driven dual parallel-connected ejector (DPE) refrigeration system was conducted using water as working fluid. Saturated steam with 2 bar and 120oC was provided by heat–pipe evacuated tube solar collector with an assistant of an electric heater. The saturated stream was used as a motive flow for the ejectors. The exergy destruction and exergetic efficiency of the main components of the DPE refrigeration system were determined and compared with those when using a single ejector (SE) under same operating conditions. It was found that the most irreversibilities of both systems occurred at the solar collector, electric boiler and ejectors, respectively. Also, the total irreversibility (Exergy destruction) of the system when using DPE was lower than using a SE. In additions, the exergetic efficiency of the ejector, evaporator, and overall system when using DPE were increased by 21%, 10%, and 27%, respectively. The system thermal ratio (STR) and coefficient of performance (COP) of the system using DPE compared with SE were increased by 20% and 23%, respectively.

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Aidoun, Zine, Khaled Ameur, Mehdi Falsafioon et Messaoud Badache. « Current Advances in Ejector Modeling, Experimentation and Applications for Refrigeration and Heat Pumps. Part 1 : Single-Phase Ejectors ». Inventions 4, n^o 1 (6 mars 2019) : 15. http://dx.doi.org/10.3390/inventions4010015.

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Ejectors used in refrigeration systems as entrainment and compression components or expanders, alone or in combination with other equipment devices, have gained renewed interest from the scientific community as a means of low temperature heat recovery and more efficient energy use. This paper summarizes the main findings and trends, in the area of heat-driven ejectors and ejector-based machines, using low boiling point working fluids, which were reported in the literature for a number of promising applications. An overall view of such systems is provided by discussing the ejector physics principles, as well as a review of the main developments in ejectors over the last few years. Recent achievements on thermally activated ejectors for single-phase compressible fluids are the main focus in this part of the review. Aspects related to their design, operation, theoretical and experimental approaches employed, analysis of the complex interacting phenomena taking place within the device, and performance are highlighted. Conventional and improved ejector refrigeration cycles are discussed. Some cycles of interest employing ejectors alone or boosted combinations are presented and their potential applications are indicated.

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Ouelhazi, I., Y. Ezzaalouni et L. Kairouani. « Parametric analysis of a combined ejector-vapor compression refrigeration cycle ». International Journal of Low-Carbon Technologies 15, n^o 3 (15 juin 2020) : 398–408. http://dx.doi.org/10.1093/ijlct/ctaa011.

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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, Hui Lan, Gang Li, Xiang Chen et Zhong Yi Su. « Analysis of Ejector in Central Air Conditioner Combined with Solar Ejector Refrigeration System ». Advanced Materials Research 860-863 (décembre 2013) : 733–36. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.733.

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Comparing with the common jet refrigeration system, a central air conditioner combined with solar ejector refrigeration system was proposed. The system characteristic was presented. It can improve the coefficient of the single solar system and solve operation problem for day-and-night, and can reduce the energy consumption of central air conditioner. A reasonable ejector to match with the central air conditioning is a main component in the system. The ejector in the solar refrigeration system is preliminary analyzed by the pneumatic function method. It will provide the important reference to improving the conditioner performance and system efficiency on air conditioning energy saving.

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Boumaraf, Latra, et Rachedi Khadraoui. « Investigation on the Performance of a Solar Hybrid Refrigeration System Using Environmentally Friendly Fluids ». International Journal of Heat and Technology 38, n^o 4 (31 décembre 2020) : 960–66. http://dx.doi.org/10.18280/ijht.380423.

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In order to evaluate the performance of a hybrid compression / ejection refrigeration system using solar energy at low or medium temperature, a simulation model of its behavior based on those of its various components has been developed. It includes in particular for the ejector, a 1-D model of the "constant section mixing" type developed in optimal transition regime. The refrigerants tested are steam for the ejector loop and the R1234yf (replacing the R134a) for the mechanical compression loop. The behavior of the H2O vapor flowing in the ejector is considered that of the perfect gas. The properties of refrigerants are calculated using REFPROP® software, everywhere else. For a cooling capacity of 10 kW and air conditioning operating conditions, the model allows to determine the main parameters of the ejector and its entrainment ratio, the thermal and mechanical COP of the whole refrigeration system as well as the necessary surface of the solar collector. Furthermore, the influence of the temperature of the boiler, the condenser, the intercooler as well as that of the evaporator on the mechanical COP of the hybrid system and the solar collection surface in particular, were examined. The results highlight that the solar refrigeration system with hybrid cycle compression/ejection using the refrigerants H2O/R1234yf allows an increase of the mechanical COP higher than 50% compared to that of the conventional refrigeration system and thus constitutes an acceptable ecologically system that can compete with the latter.

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Et.al, Anoop Kumar M. « Modelling and thermodynamic analysis of ejector flow for application at design and off design operating conditions in an ejector air conditioner ». Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, n^o 3 (11 avril 2021) : 3455–67. http://dx.doi.org/10.17762/turcomat.v12i3.1617.

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Ejector flow in an ejector air conditioning system using R245fa is analysed for entrainment ratio and potential refrigeration effect, at varying temperature and heat input conditions in the generator ranging from 60C to 100C and 2kW to 5kW respectively. The effect of varying generator temperature in cooling capacity of the system when the vapour ejectoris operating at design evaporator and condenser temperatures of 10C and 35C respectively is investigated. The mathematical model of the vapour ejector with optimum area ratio is developed and validated. A critical entrainment ratio of 0.385 is obtained corresponding to generator temperature of 100C. When the generator temperature is varied from 60C to 100C, the cooling capacity range from 0.3kW at generator heat input of 2 kW to 1.78 kW at 5 kW heat input. Further, the operation of the system is analysed for off design operating condition corresponding to reduced heat input rate in the generator. In that case the state of primary refrigerant flow in ejector inlet will be two phase and a mathematical model for two-phase ejector flow is developed and validated. Ejector flow analysis revealed the minimum quality of flow at ejector inlet to maintain adequate backpressure for condensation to occur range from 0.72 at 60C to 0.22 at 100C. The corresponding refrigeration refrigeration effect produced is less than the respective designed operation value byits 12.2% to 8%. Further, analysis of the system shows that at least 7 kW heat input at 100C is required to produce 1 ton of cooling effect. Ejector flow in an ejector air conditioning system using R245fa is analysed for entrainment ratio and potential refrigeration effect, at varying temperature and heat input conditions in the generator ranging from 60C to 100C and 2kW to 5kW respectively. The effect of varying generator temperature in cooling capacity of the system when the vapour ejectoris operating at design evaporator and condenser temperatures of 10C and 35C respectively is investigated. The mathematical model of the vapour ejector with optimum area ratio is developed and validated. A critical entrainment ratio of 0.385 is obtained corresponding to generator temperature of 100C. When the generator temperature is varied from 60C to 100C, the cooling capacity range from 0.3kW at generator heat input of 2 kW to 1.78 kW at 5 kW heat input. Further, the operation of the system is analysed for off design operating condition corresponding to reduced heat input rate in the generator. In that case the state of primary refrigerant flow in ejector inlet will be two phase and a mathematical model for two-phase ejector flow is developed and validated. Ejector flow analysis revealed the minimum quality of flow at ejector inlet to maintain adequate backpressure for condensation to occur range from 0.72 at 60C to 0.22 at 100C. The corresponding refrigeration refrigeration effect produced is less than the respective designed operation value byits 12.2% to 8%. Further, analysis of the system shows that at least 7 kW heat input at 100C is required to produce 1 ton of cooling effect.

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Besagni, Giorgio, Riccardo Mereu et Fabio Inzoli. « Ejector refrigeration : A comprehensive review ». Renewable and Sustainable Energy Reviews 53 (janvier 2016) : 373–407. http://dx.doi.org/10.1016/j.rser.2015.08.059.

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Milazzo, Adriano, et Federico Mazzelli. « Future perspectives in ejector refrigeration ». Applied Thermal Engineering 121 (juillet 2017) : 344–50. http://dx.doi.org/10.1016/j.applthermaleng.2017.04.088.

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Besagni, Giorgio, Lorenzo Croci, Paolo Bellasio et Luigi Pietro Maria Colombo. « Ejector refrigeration : perspectives and comparative analysis ». Journal of Physics : Conference Series 2116, n^o 1 (1 novembre 2021) : 012090. http://dx.doi.org/10.1088/1742-6596/2116/1/012090.

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Abstract Within the broader discussion regarding the decarbonisation of the household sector, ejector refrigeration is attracting a growing attention. This communication contributes to the present day discussion concerning the performances and the perspectives in ejector refrigeration systems. Based on a very large dataset, gathered from the previous literature (encompassing a wide range of system design, operating conditions and refrigerants), this paper proposes a comprehensive comparative analysis. First, the current trends in ejector refrigeration systems, refrigerants and performances are presented. Second, the relationships between ejector performances, refrigerants and boundary conditions (in terms of non-dimensional temperatures, to ensure generality of the proposed analysis) are presented. In conclusion, this paper is intended to provide guidelines for perspective researchers and practitioners interested in selecting suitable ejector-based systems.

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Huang, B. J., C. B. Jiang et F. L. Hu. « Ejector Performance Characteristics and Design Analysis of Jet Refrigeration System ». Journal of Engineering for Gas Turbines and Power 107, n^o 3 (1 juillet 1985) : 792–802. http://dx.doi.org/10.1115/1.3239802.

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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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Hassanain, M., E. Elgendy et M. Fatouh. « Ejector expansion refrigeration system : Ejector design and performance evaluation ». International Journal of Refrigeration 58 (octobre 2015) : 1–13. http://dx.doi.org/10.1016/j.ijrefrig.2015.05.018.

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Tashtoush, Bourhan, Tatiana Morosuk et Jigar Chudasama. « Exergy and Exergoeconomic Analysis of a Cogeneration Hybrid Solar Organic Rankine Cycle with Ejector ». Entropy 22, n^o 6 (24 juin 2020) : 702. http://dx.doi.org/10.3390/e22060702.

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Solar energy is utilized in a combined ejector refrigeration system with an organic Rankine cycle (ORC) to produce a cooling effect and generate electrical power. This study aims at increasing the utilized share of the collected solar thermal energy by inserting an ORC into the system. As the ejector refrigeration cycle reaches its maximum coefficient of performance (COP), the ORC starts working and generating electrical power. This electricity is used to run the circulating pumps and the control system, which makes the system autonomous. For the ejector refrigeration system, R134a refrigerant is selected as the working fluid for its performance characteristics and environmentally friendly nature. The COP of 0.53 was obtained for the ejector refrigeration cycle. The combined cycle of the solar ejector refrigeration and ORC is modeled in EBSILON Professional. Different parameters like generator temperature and pressure, condenser temperature and pressure, and entrainment ratio are studied, and the effect of these parameters on the cycle COP is investigated. Exergy, economic, and exergoeconomic analyses of the hybrid system are carried out to identify the thermodynamic and cost inefficiencies present in various components of the system.

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Herna´ndez, Jorge I., Roberto Best, Rube´n J. Dorantes et Claudio A. Estrada. « Study of a Solar Booster Assisted Ejector Refrigeration System With R134a ». Journal of Solar Energy Engineering 127, n^o 1 (1 février 2005) : 53–59. http://dx.doi.org/10.1115/1.1771683.

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The studies of ejector refrigeration systems employing refrigerant R134a for air conditioning are scarce and nonexistent for ice making when its potential application in developing countries will lessen their refrigeration needs. So, a parametric study for an ice making solar booster assisted ejector refrigeration system operating with R134a is carried out. System energy and exergy efficiencies as well as ejector efficiency are presented as a function of generator and condenser temperatures and booster discharge pressure. A discussion on maximum ejector efficiency and its effect in system behavior is also carried out. With results indicating that for an evaporator temperature of −10°C, the system can operate at a generator temperature of 85°C with average energy efficiencies between 0.21 and 0.58, depending on the condenser temperature. Consequently, these systems could be a solution for solar refrigeration using off-the-shelf components.

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Yin, Li Yuan, Qi Tian et Fei Fei Zhang. « Optimization of Operating Parameters of a Solar Ejector Refrigeration System on Exergy Analysis ». Applied Mechanics and Materials 178-181 (mai 2012) : 37–41. http://dx.doi.org/10.4028/www.scientific.net/amm.178-181.37.

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Exergy analysis is used as a tool to analyze the performance of a refrigeration system. In this paper, it is based on the following conditions: the solar radiation is set as 750 W/m2, the refrigerating capacity is 10 kW, R141b is fixed as the refrigerant in the refrigeration cycle and ambient temperature to be the reference temperature is 31°C. The exergy analysis results of the solar ejector refrigeration system shows that irreversible loss comes from all components and depends on the operating temperatures. The exergy efficiency increases with the condensation temperature’s decrease or the evaporation temperature’s increase. In the specific evaporation temperature and condensation temperature, the optimum generating temperature can be get when the system exergy efficiency is at its maximum. For the operating conditions in this paper, the optimum generating temperature is 95°C.

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KUMAR, RAJ, et ANIL KUMAR. « ENERGY AND EXERGY ANALYSIS OF COMPACT POWER GENERATION AND HYBRID SOLAR ENERGY-WASTE HEAT-BASED TRIPLE EFFECT EJECTOR-VAPOR ABSORPTION REFRIGERATION CYCLE ». International Journal of Air-Conditioning and Refrigeration 21, n^o 04 (décembre 2013) : 1350023. http://dx.doi.org/10.1142/s2010132513500235.

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An NH 3– H 2 O ejector-absorption refrigeration cycle, and an R-152a ejector refrigeration cycle are employed with a renewable energy power generator to make a proposed compact power generation and triple effect ejector-absorption refrigeration cycle. The exergy analysis of the cycle leads to a possible performance improvement. Approximately 71.69% of the input exergy is destructed due to irreversibilities in different components. Around 7.976% is available as the useful exergy output. The exhaust exergy lost to the environment is 20.33%, which is lower than the exhaust energy loss of 47.95%, while the useful energy output is 27.88%. The refrigerants used are of zero ODP and negligible GWP, and the CO 2 emission of the exhaust gases is very small as compared to that of the fossil fuel run engine, hence, this cycle is favorable to the global environment. The results also show that the proposed cycle has significant higher energy and exergy efficiency than the earlier investigated 'triple effect refrigeration cycle' and 'the combined power and ejector-refrigeration cycle'.

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Радченко, Андрій Миколайович, Сергій Анатолійович Кантор, Богдан Сергійович Портной et Юрій Георгійович Щербак. « ОХОЛОДЖЕННЯ ПОВІТРЯ НА ВХОДІ ГТУ З ВИКОРИСТАННЯМ РЕЗЕРВУ ХОЛОДОПРОДУКТИВНОСТІ АБСОРБЦІЙНО-ЕЖЕКТОРНОЇ ХОЛОДИЛЬНОЇ МАШИНИ В БУСТЕРНОМУ ПОВІТРООХОЛОДЖУВАЧІ ». Aerospace technic and technology, n^o 2 (26 avril 2018) : 14–19. http://dx.doi.org/10.32620/aktt.2018.2.02.

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The processes of gas turbine unit two-stage intake air cooling by absorption lithium-bromide chiller as a high temperature cooling stage to the temperature of about 15 °C and by refrigerant ejector chiller as a low temperature cooling stage to the temperature of about 10 °C through utilizing the turbine exhaust gas waste heat for hour-by-hour changing ambient air temperatures and changeable heat loads on the air coolers as consequence during 10 days of July 2017 (10–12.07.2017) for climatic conditions of the south of Ukraine are analyzed. The computer programs of the firms-producers of heat exchangers were used for gas turbine unit inlet air cooling processes simulation.It is shown that at decreased heat loads on the air coolers an excessive refrigeration capacity of combined absorption-ejector chiller exceeding current heat loads is generated which can be used for covering increased heat loads on the air coolers and to reduce the refrigeration capacity of the absorption-ejector chiller. To solve this task the refrigeration capacity required for gas turbine unit inlet air cooling is compared with an excessive refrigeration capacity of the absorption-ejector chiller exceeding current heat loads summarized during 10 days.The system of gas turbine unit inlet air cooling with a booster stage of precooling air and a base two-stage cooling air to the temperature of about 10 °C by absorption-ejector chiller has been proposed. An excessive refrigeration capacity of the absorption-ejector chiller generated during decreased heat loads on the gas turbine unit inlet air coolers that is collected in the thermal accumulator is used for gas turbine unit inlet air precooling in a booster stage of air coolers during increased heat loads on the air coolers. The results of gas turbine unit inlet air cooling processes simulation proved the reduction of refrigeration capacity of the absorption-ejector chiller by about 50 % due to the use of a booster stage for precooling air at the expanse of an excessive absorption-ejector chiller refrigeration capacity served in the thermal accumulator. The conclusion has been made about the efficient use of a booster stage of gas turbine unit inlet air cooler for precooling air by using an excessive refrigeration potential of absorption-ejector chiller saved in the thermal accumulator

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Радченко, Андрій Миколайович, Микола Іванович Радченко, Богдан Сергійович Портной, Сергій Анатолійович Кантор et Олександр Ігорович Прядко. « ВИКОРИСТАННЯ НАДЛИШКУ ХОЛОДОПРОДУКТИВНОСТІ ХОЛОДИЛЬНИХ МАШИН ПРИ ОХОЛОДЖЕННІ ПОВІТРЯ НА ВХОДІ ГТУ ». Aerospace technic and technology, n^o 5 (29 août 2020) : 47–52. http://dx.doi.org/10.32620/aktt.2020.5.06.

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The processes of the gas turbine inlet air cooling by exhaust heat conversion chillers, which utilizing the gas turbine exhaust gas heat, converting it into cold were analyzed. The use of two-stage air cooling has been investigated: to a temperature of 15°C – in an absorption lithium-bromide chiller and below to a temperature of 10°C – in an ejector chiller as stages of a two-stage absorption-ejector chiller. To simulate air cooling processes, the program "Guentner Product Calculator", one of the leading manufacturers of heat exchangers "Guentner", was used. The possibility of using the accumulated excess refrigeration capacity of a combined absorption-ejector chiller, which is formed at reduced current heat loads on air coolers at the gas turbine inlet, to cover the refrigeration capacity deficit arising at increased heat loads due to high ambient air temperatures has been investigated. The refrigeration capacity required to the gas turbine inlet air cooling was compared to an excess refrigeration capacity which excess of the current heat load. The considered air cooling system provides pre-cooling of air at the gas turbine inlet by using the excess refrigeration capacity of the absorption-ejector chiller, accumulated in the cold accumulator, to provide the required refrigeration capacity of the air pre-cooling booster stage. The simulation results proved the expediency of the gas turbine inlet air cooling using the accumulated excess refrigeration capacity of the combined absorption-ejector chiller. The proposed solution reduces by about 50% the design refrigeration capacity and, accordingly, the cost of the installed absorption lithium-bromide chiller, which acts as a high-temperature stage for cooling the ambient air at the gas turbine inlet.

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Yu, Meihong, Chen Wang, Lei Wang et Hongxia Zhao. « Optimization Design and Performance Evaluation of R1234yf Ejectors for Ejector-Based Refrigeration Systems ». Entropy 24, n^o 11 (10 novembre 2022) : 1632. http://dx.doi.org/10.3390/e24111632.

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With the increasingly serious energy and environmental problems, the R1234yf ejector refrigeration system (ERS) shows great development potential in the refrigeration industry due to its simplicity, low maintenance costs and environmentally friendly nature. However, poor ejector performance has always been the main bottleneck for system applications. In order to overcome this problem, this paper proposes a design method for R1234yf ejectors based on the gas dynamic method and optimizes the geometrical parameters including the area ratio (AR) and nozzle exit position (NXP) to improve its performance through the control variable optimization algorithms. Based on the validated simulation model, the results show that the entrainment ratio increases initially and then decreases with the increase in AR and NXP, respectively; the AR has a significant effect on the shock wave position in the mixing chamber and the NXP can directly influence the expansion state of motive fluid; the ejector performance increases by about 17% over the initial entrainment ratio by the control variable optimization algorithms. This work can guide the R1234yf ejector design and promote the development of the ERS with environmentally friendly working fluids.

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Tan, Ying Ying, et You Ming Chen. « LabVIEW Application for Data Acquisition System of Ejector Refrigerator ». Advanced Materials Research 374-377 (octobre 2011) : 456–60. http://dx.doi.org/10.4028/www.scientific.net/amr.374-377.456.

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In order to analyze the performance of ejector refrigerator, it is necessary to collect the operation parameters of the system. In this paper, the development of data acquisition(DAQ) system for ejector refrigerator is described. It is based on the technique of visual instrument and the characteristic of ejector refrigerator, using National Instrument’s product LabVIEW. The proposed DAQ system consists of a set of sensors for measuring operating parameters of ejector refrigerator. The collected data are ﬁrst conditioned using Agilent 34970 data acquisition switch unit and then interfaced to a PC using RS232. The LabVIEW program is used to further process, display and store the collected data in the PC disk. It can realize the real-time data acquisition of temperature, water flow rate and pressure as well as data transmission, processing, and display, in addition to providing users with historic data inquire. The proposed software architecture permits the rapid system development and has the advantage of ﬂexibility and it can be easily altered for application in other refrigeration systems.

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Sun, Da-Wen. « Variable geometry ejectors and their applications in ejector refrigeration systems ». Energy 21, n^o 10 (octobre 1996) : 919–29. http://dx.doi.org/10.1016/0360-5442(96)00038-2.

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Arifianto, Enang Suma, Ega Taqwali Berman et Mutaufiq Mutaufiq. « Investigation on the improvement of car air conditioning system performance using an ejector ». MATEC Web of Conferences 197 (2018) : 08013. http://dx.doi.org/10.1051/matecconf/201819708013.

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The purpose of this research is to know the improvement of car air conditioner system performance using an ejector. The study was conducted on a car engine with power 100 PS (74 kW) @ 5000 rpm. The test procedure is carried out under two conditions: the normal refrigeration cycle mode and the refrigeration cycle mode with the ejector. The working fluid used in the refrigeration cycle is R-134a. Performance data was measured on engine revolutions ranging from 1500 - 3000 rpm. Finally, the results showed that ejector usage on AC system generates an increase in the refrigeration effect and coefficient of performance (COP) of 25% and 22%, respectively. This has implications to better cooling capacity and compressor work that is lighter.

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Dudar, Adam, Dariusz Butrymowicz, Kamil Śmierciew et Jarosław Karwacki. « Exergy analysis of operation of two-phase ejector in compression refrigeration systems ». Archives of Thermodynamics 34, n^o 4 (1 décembre 2013) : 107–22. http://dx.doi.org/10.2478/aoter-2013-0032.

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Abstract Paper deals with theoretical analysis of possible efficiency increase of compression refrigeration cycles by means of application of a twophase ejector. Application of the two phase ejector in subcritical refrigeration system as a booster compressor is discussed in the paper. Results of exergy analysis of the system operating with various working fluids for various operating conditions have been shown. Analysis showed possible exergy efficiency increase of refrigeration compression cycle.

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Riaz, Fahid, Kah Hoe Tan, Muhammad Farooq, Muhammad Imran et Poh Seng Lee. « Energy Analysis of a Novel Ejector-Compressor Cooling Cycle Driven by Electricity and Heat (Waste Heat or Solar Energy) ». Sustainability 12, n^o 19 (4 octobre 2020) : 8178. http://dx.doi.org/10.3390/su12198178.

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Low-grade heat is abundantly available as solar thermal energy and as industrial waste heat. Non concentrating solar collectors can provide heat with temperatures 75–100 °C. In this paper, a new system is proposed and analyzed which enhances the electrical coefficient of performance (COP) of vapour compression cycle (VCC) by incorporating low-temperature heat-driven ejectors. This novel system, ejector enhanced vapour compression refrigeration cycle (EEVCRC), significantly increases the electrical COP of the system while utilizing abundantly available low-temperature solar or waste heat (below 100 °C). This system uses two ejectors in an innovative way such that the higher-pressure ejector is used at the downstream of the electrically driven compressor to help reduce the delivery pressure for the electrical compressor. The lower pressure ejector is used to reduce the quality of wet vapour at the entrance of the evaporator. This system has been modelled in Engineering Equation Solver (EES) and its performance is theoretically compared with conventional VCC, enhanced ejector refrigeration system (EERS), and ejection-compression system (ECS). The proposed EEVCRC gives better electrical COP as compared to all the three systems. The parametric study has been conducted and it is found that the COP of the proposed system increases exponentially at lower condensation temperature and higher evaporator temperature. At 50 °C condenser temperature, the electrical COP of EEVCRC is 50% higher than conventional VCC while at 35 °C, the electrical COP of EEVCRC is 90% higher than conventional VCC. For the higher temperature heat source, and hence the higher generator temperatures, the electrical COP of EEVCRC increases linearly while there is no increase in the electrical COP for ECS. The better global COP indicates that a small solar collector will be needed if this system is driven by solar thermal energy. It is found that by using the second ejector at the upstream of the electrical compressor, the electrical COP is increased by 49.2% as compared to a single ejector system.

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Yang, Dazhang, Yang Li, Jing Xie et Jinfeng Wang. « Energetic and entropy analysis of a novel transcritical CO2 two-stage compression/ejector refrigeration cycle for shipboard cold chamber ». Thermal Science, n^o 00 (2022) : 181. http://dx.doi.org/10.2298/tsci220702181y.

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The adverse effects of global warming and climate change require critical measures for marine refrigeration technology because of its impact on greenhouse gas emissions. A novel transcritical CO2 two-stage compression/ejector refrigeration cycle for shipboard cold chamber is proposed in this research. A comparative analysis was conducted between the basic transcritical CO2 two-stage compression cycle and the cycle equipped with a two-phase ejector considering the coefficient of performance. Meanwhile, the refrigeration cycle was analyzed using entropy analysis to elucidate the distribution of irreversible losses in each component of the two-stage compression/ejector refrigeration cycle, and the effects of system parameters such as the evaporating and gas cooler outlet temperatures as well as the intermediate and discharge pressures on the cycle were investigated. The results showed that the ejector had the largest power capability loss, accounting for 26.95 % of the overall system, which is followed by the low-pressure compressor with 26.06 %. The coefficient of performance of basic and ejector system significantly increase as the gas cooler outlet temperature and intermediate pressure decrease as well as the evaporating temperature increases. Furthermore, the entropy production of the system components decreases gradually with increasing evaporating temperature, with the greatest reduction in the ejector. In addition, the entropy production of the two-phase ejector remains constant with the increase of the high-pressure side discharge pressure and gas cooler outlet temperature.

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Wakchaure, P. V. « Experimental Analysis of Refrigeration Ejector System by using Different Organic Refrigerants ». International Journal for Research in Applied Science and Engineering Technology 9, n^o VII (10 juillet 2021) : 281–88. http://dx.doi.org/10.22214/ijraset.2021.36297.

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This paper presents the experimental analysis performed on ejectors to optimize operating conditions like evaporator temperature, condenser temperature and generator temperature. Using the environmentally friendly working fluid R134a, R152a, R600a, R717 (Ammonia). Parametric analysis was performed to review the effect of blending chamber geometry on ejector performance which has direct impact on coefficient of performance of ejector refrigeration cycles. Results show that operating conditions and thus the effect of the deflection of the primary flow on the secondary flow is set. CFD simulations was performed to identify optimum geometry and optimum operating condition

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Khalil, A., M. Fatouh et E. Elgendy. « Ejector design and theoretical study of R134a ejector refrigeration cycle ». International Journal of Refrigeration 34, n^o 7 (novembre 2011) : 1684–98. http://dx.doi.org/10.1016/j.ijrefrig.2011.01.005.

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Manoj, P. J., et V. Lijo. « Recent developments in ejector refrigeration system ». IOP Conference Series : Materials Science and Engineering 1114, n^o 1 (1 mars 2021) : 012046. http://dx.doi.org/10.1088/1757-899x/1114/1/012046.

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Chen, Xiangjie, Siddig Omer, Mark Worall et Saffa Riffat. « Recent developments in ejector refrigeration technologies ». Renewable and Sustainable Energy Reviews 19 (mars 2013) : 629–51. http://dx.doi.org/10.1016/j.rser.2012.11.028.

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Wang, Lei, Jiapeng Liu, Tao Zou, Jingwei Du et Fengze Jia. « Auto-tuning ejector for refrigeration system ». Energy 161 (octobre 2018) : 536–43. http://dx.doi.org/10.1016/j.energy.2018.07.110.

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Pardiñas, Ángel Á., Michael Jokiel, Christian Schlemminger, Håkon Selvnes et Armin Hafner. « Modeling of a CO2-Based Integrated Refrigeration System for Supermarkets ». Energies 14, n^o 21 (21 octobre 2021) : 6926. http://dx.doi.org/10.3390/en14216926.

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An integrated energy system that consists of a centralized refrigeration unit can deliver the entire HVAC&R (heating, ventilation, air conditioning, and refrigeration) demand for a supermarket. CO2 (R744) is a natural refrigerant that is becoming increasingly popular for these centralized units due to significant energy and cost savings, while also being sustainable, safe, and non-toxic. This study focuses on the fully integrated CO2 refrigeration system configuration for a supermarket in Porto de Mos, Portugal, which was equipped and fully monitored through the EU-funded project MultiPACK. A dynamic system model was developed in Modelica and validated against measurement data from the site recorded for one week. The model is used to provide additional ejector performance data supporting the obtained measurement data and to evaluate the system configuration at equivalent boundary conditions. The simulation results show that the installation of a vapor ejector (high-pressure lift) is sufficient to improve the efficiency of the unit compared to an ejector-less (high-pressure valve) system. However, more notable enhancements are achieved by including additional flooded evaporation with liquid ejectors and smart regulation of the receiver pressure, adding up to a global efficiency increase of 15% if compared to the high-pressure valve system during the validation week.

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Shovon, Md Khairul Bashar, Raman Senthil Kumar, Tae Ho Kim et Heuy Dong Kim. « Study on Conceptual Design of a Solar Ejector Refrigeration System ». International Journal of Air-Conditioning and Refrigeration 28, n^o 01 (10 février 2020) : 2030001. http://dx.doi.org/10.1142/s2010132520300013.

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The refrigeration system based on the conventional compression cycle consumes an enormous amount of high-grade energy. Using fossil fuels as the energy sources results in the addition of CO2 into the atmosphere and consequently stimulating higher greenhouse effect. The ejector refrigeration systems powered by renewable energy sources would be an effective alternative without increasing global CO2 footprint. In this study, the performance characteristics of a solar ejector refrigeration system working with R718 are analytically calculated by using a one-dimensional flow model. At the critical mode, the solar ejector-refrigeration system is analyzed at various working conditions such as condenser temperature, evaporator temperature, generator temperature, and ejector area ratio. The critical system performance is analyzed to meet any designated working conditions with a wide range of condenser temperatures. It is found that during the critical mode of operation, higher area ratio, higher evaporator temperature and lower generator temperature enhance the performance of the system. The minimum evaporator temperature, and the maximum generator temperature designed to acquire the required coefficient of performance value are also calculated.

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Chen, Jin Zeng, Yan Fei Li et G. H. Li. « A New Method for Desalination of Seawater With Steam-Ejector Refrigeration Plant ». Applied Mechanics and Materials 94-96 (septembre 2011) : 273–79. http://dx.doi.org/10.4028/www.scientific.net/amm.94-96.273.

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Desalination of seawater has played an important role in many arid regions in the world. There are many methods for desalination of seawater, such as MED, MSF, RO, ED, TVC, and MVC, etc. Different methods have different advantages and disadvantages. In the present work, a new method for desalination of seawater with steam-ejector refrigeration plant was introduced. The main purpose of the new method is a hybrid plant of TVC and steam-ejector refrigeration. In the hybrid circle, no other energy was need. When the steam-ejector refrigeration plant is working, the seawater as cooling water is introduced into evaporator of TVC and evaporates. The vapor getting in TVC is extracted by a second steam-ejector, together with the active steam, is used as source of heat for desalination. The main advantage of this hybrid plant is that part of the heat energy of cooling water in refrigeration is reused. Comparing with other distillation method desalination of seawater, the energy consumption is much less. Especially on marine usage, the advantage is clear.

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NAKAGAWA, MASAFUMI, ARIEL R. MARASIGAN et TAKANORI MATSUKAWA. « EXPERIMENTAL ANALYSIS OF TWO-PHASE EJECTOR SYSTEM WITH VARYING MIXING CROSS-SECTIONAL AREA USING NATURAL REFRIGERANT CO2 ». International Journal of Air-Conditioning and Refrigeration 18, n^o 04 (décembre 2010) : 297–307. http://dx.doi.org/10.1142/s2010132510000320.

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The use of two-phase ejector in improving the performance of transcritical CO2 refrigeration system needs further experimental verification particularly the effects of its geometrical design. In this study, experimental data were gathered for ejectors with different mixing cross-sectional areas at different operating temperature and pressure. The results have shown that a smaller mixing area yields higher efficiency due to its higher pressure recovery and entrainment ratio, but its advantages are limited to lower ejector inlet pressure Pc. A larger mixing area is required for higher cooling capacity which can be achieved at higher ejector inlet pressure or lower ejector inlet temperature but excessive increase in this area considerably decreases the efficiency of the system. In this study, the ejector with the largest mixing area was the most inefficient and reduced the COP up to 10% compared to most efficient type. It demonstrates the significant effect of ejector's geometrical features, particularly the mixing cross-sectional area and its related geometrical ratio, in the performance of CO2 ejector system. The effect of motive nozzle inlet condition on pressure recovery profile has been more evident for ejector with smaller mixing area while the evaporator temperature has the least effect in the performance of the system. In the conditions used in this study, using ejector yielded a COP improvement of up to 35% compared to the conventional system.

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Li, Yang, et Song Lv. « Research of Solar Refrigeration Technology ». Advanced Materials Research 1008-1009 (août 2014) : 11–15. http://dx.doi.org/10.4028/www.scientific.net/amr.1008-1009.11.

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This paper introduces the characteristics of solar energy and expounds the fundamental principle of the solar absorption refrigeration, adsorption refrigeration and ejector refrigeration.It also analyzes their respective advantages and disadvantages of three solar refrigeration techniques, and the future research direction of solar refrigeration technique is prospected.

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