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Open AccessArticle

An Object-Oriented R744 Two-Phase Ejector Reduced-Order Model for Dynamic Simulations

Institute of Thermal Technology, Silesian University of Technology, Konarskiego 22, 44-100 Gliwice, Poland
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Energies 2019, 12(7), 1282; https://doi.org/10.3390/en12071282
Received: 1 March 2019 / Revised: 19 March 2019 / Accepted: 27 March 2019 / Published: 3 April 2019
(This article belongs to the Special Issue Heat and Mass Transfer in Energy Systems)
The object-oriented two-phase ejector hybrid reduced-order model (ROM) was developed for dynamic simulation of the R744 refrigeration system. OpenModelica software was used to evaluate the system’s performance. Moreover, the hybrid ROM results were compared to the results given by the non-dimensional and one-dimensional mathematical approaches of the R744 two-phase ejector. Accuracy of all three ejector models was defined through a validation procedure for the experimental results. Finally, the dynamic simulation of the hybrid ROM ejector model integrated with the R744 refrigeration system was presented based on the summer campaign at three different climate zones: Mediterranean, South American and South Asian. The hybrid ROM obtained the best prediction of ejector mass flow rates as compared with other ejector models under subcritical and transcritical operating conditions. The dynamic simulations of the R744 ejector-based system indicated the ejector efficiency variations and the best efficiency at the investigated climate zones. The coefficient of performance (COP) varied from 2.5 to 4.0 according to different ambient conditions. The pressure ratio of 1.15 allowed a more stabilised system during the test campaign with an ejector efficiency from 20% to over 30%. View Full-Text
Keywords: R744; two-phase ejector; refrigeration; dynamic simulation; low-order model; object-oriented modelling R744; two-phase ejector; refrigeration; dynamic simulation; low-order model; object-oriented modelling
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Haida, M.; Fingas, R.; Szwajnoch, W.; Smolka, J.; Palacz, M.; Bodys, J.; Nowak, A.J. An Object-Oriented R744 Two-Phase Ejector Reduced-Order Model for Dynamic Simulations. Energies 2019, 12, 1282.

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