One dimensional steam ejector model based on real fluid property

Abstract

The one-dimensional ejector model based on the real fluid property is proposed to design the steam ejector geometries and to predict its performance. This model is developed from the one-dimensional compressible flow of steam-water which was firstly proposed by Stoecker (1958). The ejector geometry and performance determined by the proposed model are validated with the experimental results to ensure that the proposed model can be used efficiently for designing the steam ejector. Also, the results obtained from the one-dimensional model based on the ideal gas are compared with those obtained from the proposed model. It is found that both models can efficiently be used to design the ejector geometry and to predict the performance (in terms of entrainment ratio and critical condenser pressure). However, the one-dimensional model based on the ideal gas provides relatively low temperatures at each state compared to the proposed model. The calculated temperature is well below the freezing point while that calculated by the proposed model provides fluid properties at equilibrium condition. In addition, the condensation process of the supersonic flow is involved in many processes inside the ejector. This indicates that the ideal gas assumption for the wet fluid (steam is classified as the wet fluid) might not suitable for analysing the process of the ejector.