Investigation on the influence of geometric parameters on two-phase ejector performance with R290

In this paper, the effect of geometric parameters on a two-phase ejector performance was experimentally studied, and the R290 was used as the working fluid. The four geometric parameters of the ejector were discussed in detail, including the diameter of the nozzle throat (D_t), the nozzle exit position (NXP), the diameter of the mixing section (D_m) and the length of the mixing section (L_m). The experimental results indicated that the pressure lift ratio (r_p) of the ejector was sensitive to D_t and NXP. Within the increase of D_t and NXP discussed in this paper, the r_p of the ejector varied from 1.13 to 1.33 and 1.32 to 1.07, respectively. In addition, a maximum r_p of the ejector could be obtained when D_m was 3 mm to 4 mm under different nozzle throat diameter. When the D_t was 0.7 mm, the entrainment ratio of the ejector varied from 0.402 to 1.406 as the D_m varied from 2 mm to 6 mm. The L_m of the ejector diffuser had little effect on the ejector performance. Moreover, the empirical correlations for the efficiencies of R290 two-phase ejector components were summarized based on the experimental result and ejector model.