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    Experimental determination of the optimum performance of ejector refrigeration system depending on ejector area ratio
    (ELSEVIER SCI LTD, 2008) Yapıcı, R.; Ersoy, H. Kürşad; Aktoprakoğlu, A.; Halkacı, Hüseyin S.; Yiğit, Osman
    The performance of the ejector refrigeration system using ejectors with cylindrical mixing chamber is studied at operating conditions with choking in the mixing chamber. The condenser pressure is chosen so that the secondary flow choking can occur even in the ejector with the smallest area ratio. In the present study, the performance of the constructed system is determined by using six configurations of ejector and R-123 as working fluid in the system. The study is performed over a range of the ejector area ratio from 6.5 to 11.5 at the compression ratio 2.47. In the studied range, the experimental coefficient of performance of the system rises from 0.29 to 0.41, as the optimum generator temperature increases from 83 to 103 degrees C. Similar results were also found in the parametric study when the efficiencies of the nozzle and diffuser are taken as 0.90. (C) 2008 Elsevier Ltd and IIR. All rights reserved.
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    Performance Characteristics of Ejector Expander Transcritical CO2 Refrigeration Cycle
    (SAGE PUBLICATIONS LTD, 2012) Ersoy, H. Kürşad; Bilir, Nagihan
    The effects on the performance of the basic CO2 refrigeration cycle when using an ejector as the expander to recover expansion work were investigated. A two-phase constant area ejector flow model was used in the ejector analysis. The coefficient of cooling performance and gas cooler pressure that yielded the maximum exergy efficiency, suction nozzle pressure drop, and optimum values for the ejector area ratio were determined for various evaporator and gas cooler outlet temperatures. Parametric studies were performed using engineering equation solver. The suction nozzle pressure drop had a significant effect on the ejector area ratio, coefficient of cooling performance, and exergy efficiency. It is necessary to design an ejector with the optimum area ratio to achieve the optimum pressure drop and maximum performance. Cycle that use the ejector as an expander always has higher coefficient of performance and exergy efficiency than conventional cycle under any operating condition. The irreversibility decreases compared to the classic refrigeration cycle when the ejector or turbine are used as an expander. The analysis results showed that - under a gas cooler pressure of 9.5 MPa, gas cooler outlet temperature of 40 degrees C, evaporator temperature of 5 degrees C, and cooling capacity of 3.5kW - the total irreversibility of the ejector system was lower than those of the basic and turbine expander systems by 39.1% and 5.46%, respectively.