An improved 1-D thermodynamic modeling of small two-phase ejector for performance prediction and design

In this paper, an improved thermodynamic model for the design of a small two-phase ejector is proposed by using the constant-pressure mixing modeling method. Particularly, the mixing process modeling is associated with the area variation of the mixing section, where a corresponding area ratio of the mixing section entrance to exit is introduced. Meanwhile, the mixing pressure is determined by solving model equations under given operating conditions. Furthermore, the effects of the mixing area ratio, operating conditions, ejector components efficiencies on the ejector performance and geometry parameters are analyzed by the proposed model. The results show that the entrainment ratios increase from 0.47 to 1.14 as mixing area ratios range from 1.0 to 1.2 under the given conditions. The mixing area ratio has significant influences on the ejector performance at lower pressure lift ratio, higher primary fluid temperature and lower secondary fluid temperature. It can be concluded that the entrainment ratio, mixing pressure and mixing velocity of ejector could be improved with the mixing area ratio increasing. And it is further confirmed that the constant-pressure mixing ejector provides better performance than the constant-area mixing ejector under design operating conditions. The research results can provide theoretical guidance about the ejector design and performance predictions.