Mixing process of two streams within a steam ejector from the perspectives of mass, momentum and energy transfer

Abstract

There is not a specific technical proposal to be able to achieve a clear presentation of the complex mixing process between the primary and entrained flows within the steam ejector. In this study, a novel ejector model with species transport is proposed that can clearly elucidate how, when, where and to what extent the two streams mix. Systematic quantitative analysis toward the mixing of two streams is performed from the perspectives of mass, momentum and energy transfer. Further, the similarities and differences of the mixing process among three analytical perspectives are clarified. Key results revealed that the mixing mainly occurs at the nearby of the local mixing layer, and there are still some distances from the homogenous mixing state after the mixing chamber process, only up to 80.6% the mixing uniformity φ obtains. Additionally, the mixing layer follows a similar growth trajectory, and φ increases as mixing continues regardless of an analytical perspective. However, a much faster mixing is observed from the mass transfer perspective. Specifically, φM (80.6%) is significantly larger than φV (60.7%) and φE (59.6%) at the mixing chamber outlet. It can be concluded that the essential mass mixing laws of the two streams are not necessarily achieving a complete replication whether from the perspective of momentum or energy transfer. These key findings provide a more in-depth and comprehensive understanding of the mixing process inside the ejector.