Relation between entrainment performance and mixing efficiency in solar-desalination steam ejector with non-equilibrium phase transformation

Non-equilibrium phase transformation of condensable gas greatly affects the mixing efficiency and thus the entrainment performance of steam ejector in solar-driven desalination system, but their underlying relation remains unclear. In this study, a novel ejector model integrating non-equilibrium phase transformation with species transport is established. The transonic phase-changing mixing flow characteristics inside steam ejector are explored from multiple perspectives, with emphasis on how operating parameters affect the mixing layer development and mass transfer laws. Results revealed that phase transformation hinders the secondary fluid permeation into the primary jet flow, and the original exponential development of mixing layer disappears. The mixing layer growth and the entrainment performance of ejector largely governed by the mass transfer capacity, and a strong linear correlation exists among the entrainment ratio ε, non-mixing length λl and mass transfer ratio λṁ. The three peak at a primary fluid pressure Pp of 460 kPa before declining, increase distinctly with secondary fluid pressure Ps, and remain constant until the back pressure Pb exceeds its critical value. Across the tested ranges of Pp, Ps and Pb, λṁ increases by up to 212.5% and 168.8%, and decreases by up to 95.6%, respectively.