Document Type : Research Paper


1 Dept. of Mech. Eng., K. N. Toosi University of Technology., Tehran, Iran

2 Professor of Mechanical Engineering K.N. Toosi university of Technology


This paper presents a novel 1D modeling approach to optimize steam ejector entrainment ratios, introducing new definitions of ejector efficiency and methods for enhancement. Using the proposed model, an ejector is tailored for specific boundary conditions with available CFD results for validation. Dimensional and geometrical parameters are computed from the theoretical 1D model, and various geometries are explored using CFD to determine entrainment ratios.
Innovative definitions of ejector efficiency are introduced. The first definition compares the entrainment ratio of the ejector to a system comprising a steam compressor, turbine, and mixer, yielding an efficiency of 13.5% under specified conditions. The second, more practical definition calculates the maximum achievable entrainment ratio, disregarding frictional losses, resulting in an efficiency of 70%.
An algorithm is proposed to optimize ejector dimensions to approach this maximum. Using this algorithm, the optimum throat diameter was determined through CFD analysis, demonstrating an increase in the entrainment ratio from 0.7 to 1.25. The theoretical maximum value calculated by the 1D model is 1.282, indicating 97.7% of the theoretical maximum was achieved in CFD simulations. This highlights the significant improvement in the entrainment ratio using the 1D model and delineates its limit under given conditions.
The third definition establishes the theoretical maximum entrainment ratio given specific boundary conditions and dimensions, assuming no losses in the nozzle, mixing process, or diffuser, yielding an efficiency of 81% for the same ejector studied.

Graphical Abstract

A novel 1D model approach to optimize the entrainment ratio of a steam ejector and introducing novel definitions of ejector efficiency


Main Subjects