A novel 1-D single-mixed-flow homogeneous equilibrium model of two-phase ejector using CO2 as refrigerant

This paper introduces a novel 1-D single-mixed-flow homogeneous equilibrium model (HEM) based on finite volume method (FVM), applicable to the entire ejector domain. The proposed 1-D HEM was validated against independent experimental data from the open literature, demonstrating that the relative deviations in ejector outlet pressure and motive flow mass flow rate fall within 10 % and 15 %, respectively. Additionally, the comparison results indicate that the novel 1-D HEM exhibits greater efficiency and stability without compromising accuracy compared to existing more complicated 1-D HEM models. The developed 1-D model demonstrates significant value in the design process, facilitating a comprehensive parametric analysis of ejector geometry. Four key parameters – the diameter of the constant-area mixing section, the length and angle of the ejector’s diffuser, and the wall roughness – were investigated to assess their impact on ejector performance. The results indicate that the diameter of the constant-area mixing section has the most pronounced influence on ejector performance, with a smaller diameter enhancing pressure recovery and efficiency. Additionally, the modeling analysis suggests that a larger diffuser angle improves ejector performance. In contrast, the diffuser length and wall roughness exhibit relatively minor effects compared to the other parameters. The simulation results can serve as a valuable guide for ejector design and parametric analysis.