Performance of non-equilibrium condensation flow in wet steam zone of steam turbine based on modified model

• Published in: Energy (Oxford) 2023-03, Vol.267, p.126571, Article 126571
• Main Authors: Hu, Pengfei, Zhao, Pu, Li, Qi, Hou, Tianbo, Wang, Shibo, Cao, Lihua, Wang, Yanhong
• Format: Article
• Language: English
• Subjects: Expansion rate; Modified model; Non-equilibrium condensation; Wet steam
• ISSN: 0360-5442
• DOI: 10.1016/j.energy.2022.126571

In order to accurately describe the homogeneous nucleation process of wet steam two-phase flow and improve the reliability of steam condensation flow calculation, in this paper the classical homogeneous nucleation theory is deduced and summarized based on the theory of thermodynamic free energy of molecular condensation, and a more accurate modified homogeneous nucleation model is proposed based on the Kantrowitz non-isothermal modified nucleation model. Firstly, the non-equilibrium condensation flow in Moses-Stein nozzle is calculated using presented modified model. It is found that the simulated results by the modified model are in good agreement with the previous experimental results, and the minimum supercooling degree required for nucleation is about 17 K. In addition, the effect of steam expansion rate on nucleation of Dykas cascade is also investigated. It is found that increasing inlet steam superheat and decreasing expansion rate can reduce the non-equilibrium condensation flow loss. Finally, the non-equilibrium condensation flow in three-dimensional turbine cascade is numerically studied. The results indicate that the values of expansion rate, nucleation rate, droplet number and wetness will decrease with the increase of blade height. •The modified model for wet steam non-equilibrium condensation is presented.•Condensation performances are studied for real three-dimensional twisted blade.•Increasing steam superheat and decreasing expansion rate reduce condensation loss.