Dynamic modeling of an R245fa ejector based refrigeration system

• Published in: International journal of refrigeration 2019-11, Vol.107, p.262-274
• Main Authors: Narimani, Elhameh, Sorin, Mikhail, Micheau, Philippe, Nesreddine, Hakim
• Format: Article
• Language: English
• Subjects: Approche de la frontière mobile; Control systems; Control systems design; Dynamic modeling; Dynamic models; Détendeur; Ejection; Ejector; Ejector refrigeration system (ERS); Enthalpy; Evaporators; Expansion valve; Gas expanders; Heat conductivity; Heat exchange; Heat exchangers; Heat transfer; Modélisation dynamique; Moving boundary approach; Performance prediction; Pumps; Refrigeration; Système frigorifique à éjecteur; Thermodynamic models; Échange de chaleur; Éjecteur
• ISSN: 0140-7007; 1879-2081
• DOI: 10.1016/j.ijrefrig.2019.08.013

•The moving boundary approach is used to develop the dynamic models of the three heat exchangers in an ejector based refrigeration system (ERS).•The 1-D thermodynamic model of the ejector capable of predicting its performance in both critical and subcritical modes is developed.•The pump and expansion valve are modeled using the set of algebraic equations.•The general dynamic model of the ERS is developed by interconnecting the components models. The dynamic behavior of the ejector refrigeration system (ERS) plays an important role in its performance prediction and control system design. This paper numerically and experimentally investigated ERS dynamic behavior by connecting generator, condenser and evaporator dynamic models into a single ERS dynamic model, as the heat exchangers dominate ERS thermal dynamics. The developed dynamic models of the heat exchangers were based on the moving boundary approach. A 1-D thermodynamic model of the ejector was also developed to evaluate the fluid behavior through the ejector. The pump and expansion valve were modeled using algebraic equations, as they were considered as steady state components in the system. The developed ERS dynamic model was validated experimentally by measuring the transient response to the step change of the pump speed. The validation studies revealed that the model is able to capture the refrigeration system's dynamics in terms of the pressures and outlet specific enthalpies of the heat exchangers, with relative errors of less than 3.78 and 0.5%, respectively.