Performance evaluation and operation optimization of the steam ejector based on modified model

Abstract

Steam ejectors are widely applied in various industries, as they have the ability to improve the low-grade energy. In this work, a modified model is proposed and employed to evaluate steam ejector performance and to optimize steam ejector operation. Firstly, the modified nucleation model is built. Four models consisting of different nucleation models and droplet growth models are adopted to predict the non-equilibrium condensation. The results show that the model consisting of the modified nucleation model and Young′s droplet growth model (ϕ=0.75,α=9) presents the best ability to predict pressure distribution and the Wilson point than the other three models. Secondly, a steam ejector is investigated using the modified model and the ideal gas model, the results show that the modified model is more suitable to predict the steam ejector wall pressure distribution than the ideal gas model, and the steam ejector performance predicted by the modified shows less error than that predicted by the ideal gas, compared with that obtained by the experiment. The relative error of critical condenser pressure reduces from 4.4% to 1.5%. At last, the steam ejector operation is optimized based on the modified model, and the results is analyzed in sufficient detail.