Numerical Investigation of a Refrigeration Ejector: Effects of Environment-Friendly Refrigerants and Geometry of the Ejector Mixing Chamber
Hadi Ahmadi Moghaddam 1, Maziar Shafaee 1 * , Rouzbeh Riazi 1
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1 Faculty of New Sciences and Technologies, University of Tehran, IRAN
* Corresponding Author

Abstract

In refrigeration cycles, ejectors are employed as thermo-compressors. To improve their performance, the operational conditions and geometrical parameters could be evaluated. In this numerical study firstly, the effects of refrigerants R1234ze(E) and R1234yf as replacements for R134a are investigated. Results showed that using R1234yf, the entrainment ratio and the coefficient of performance (COP) increase 10% and 1.7% respectively. When R1234ze is used, the entrainment ratio and the COP decrease 3.4% and 7% respectively compared with R134a. For the boiler operating temperature, an optimum value was found at which the entrainment ratio and the COP are maximum. However, the entrainment ratio and the COP enhance by increment of the evaporator temperature. In the second part, the effect of the mixing chamber convergence angle is studied. Results illuminated that by increment of the converging angle up to a certain value, the entrainment ratio and the COP enhance, but beyond the optimum angle, a reverse behavior is observed. However, by increment of the convergence angle, the critical back temperature declines continually. By increase of the convergence angle, the flow field inside the ejector is affected, and weaker shock waves are established at the end of mixing chamber that influence the critical back temperature.

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Article Type: Research Article

https://doi.org/10.29333/ejosdr/5737

, 2019 - Volume 3 Issue 3, Article No: em0090

Publication date: 21 Mar 2019

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Article Downloads: 475

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