Performance of supersonic steam ejectors considering the nonequilibrium condensation phenomenon for efficient energy utilisation

Yang, Yan; Zhu, Xiaowei; Yan, Yuying; Ding, Hongbing; Wen, Chuang

Abstract

Supersonic ejectors are of great interest for various industries as they can improve the quality of the low-grade heat source in an eco-friendly and sustainable way. However, the impact of steam condensation on the supersonic ejector performances is not fully understood and is usually neglected by using the dry gas assumptions. The non-equilibrium condensation occurs during the expansion and mixing process and is tightly coupled with the high turbulence, oblique and expansion waves in supersonic flows. In this paper, we develop a wet steam model based on the computational fluid dynamics to understand the intricate feature of the steam condensation in the supersonic ejector. The numerical results show that the dry gas model exaggerates the expansion characteristics of the primary nozzle by 21.95%, which predicts the Mach number of 2.00 at the nozzle exit compared to 1.64 for the wet steam model. The dry gas model computes the static temperature lower to 196 K, whereas the wet steam model predicts the static temperature should above the triple point due to the phase change process. The liquid fraction can reach 7.2% of the total mass based on the prediction of the wet steam model. The performance analysis indicates that the dry gas model over-estimates a higher entrainment ratio by 11.71% than the wet steam model for the steam ejector.

Citation

Yang, Y., Zhu, X., Yan, Y., Ding, H., & Wen, C. (2019). Performance of supersonic steam ejectors considering the nonequilibrium condensation phenomenon for efficient energy utilisation. Applied Energy, 242, 157-167. https://doi.org/10.1016/j.apenergy.2019.03.023

• Journal Article Type: Article
• Acceptance Date: Mar 5, 2019
• Online Publication Date: Mar 15, 2019
• Publication Date: May 15, 2019
• Deposit Date: Mar 19, 2019
• Publicly Available Date: Mar 16, 2020
• Journal: Applied Energy
• Print ISSN: 0306-2619
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 242
• Pages: 157-167
• DOI: https://doi.org/10.1016/j.apenergy.2019.03.023
• Public URL: https://nottingham-repository.worktribe.com/output/1665626
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0306261919304209