Polydispersed droplet spectrum and exergy analysis in wet steam flows using method of moments

Ding, Hongbing; Tian, Yuhe; Wen, Chuang; Wang, Chao; Sun, Chunqian

Abstract

In steam turbine flow, the complex droplet spectrum caused by nonequilibrium condensation is necessary to be modeled accurately to predict the droplet behavior and estimate the exergy destruction and erosion rate. This study built and validated a polydispersed model with Quadrature method of moments (QMOM), consisting of transition SST model, the moments and entropy generation. A spline-based algorithm was used to reconstruct the shape of the probability density function (PDF) of radius. It’s proved that the polydispersed model has a better prediction result for Sauter radius compare with monodispersed model. Then, the distributions of moments and droplet spectra in the nozzle with effects of asymmetric lambda shock and evaporation were investigated. The shape of droplet spectrum is closer to gamma distribution in nucleation zone and log-normal distribution in growth zone when outflow is supersonic. In the turbine, because the oblique shock induces complex evaporation and secondary condensation, the reconstructed shape is closer to gamma distribution. Finally, the obtained maximum exergy destruction is 25.293 kJ/kg. The rate of exergy destruction increases from 1.04% to 4.45%. The range of Baumann factor is 0.574–1.312. Besides, the erosion rate in polydispersed model is only 58.4–64.3% of monodispersed model. The polydispersed model used in this study can predict the droplet spectrum and energy loss of the turbine systems more accurately.

Citation

Ding, H., Tian, Y., Wen, C., Wang, C., & Sun, C. (2021). Polydispersed droplet spectrum and exergy analysis in wet steam flows using method of moments. Applied Thermal Engineering, 182, Article 116148. https://doi.org/10.1016/j.applthermaleng.2020.116148

• Journal Article Type: Article
• Acceptance Date: Sep 28, 2020
• Online Publication Date: Oct 2, 2020
• Publication Date: Jan 5, 2021
• Deposit Date: Jan 25, 2021
• Publicly Available Date: Oct 3, 2021
• Journal: Applied Thermal Engineering
• Print ISSN: 1359-4311
• Electronic ISSN: 1873-5606
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 182
• Article Number: 116148
• DOI: https://doi.org/10.1016/j.applthermaleng.2020.116148
• Keywords: Industrial and Manufacturing Engineering; Energy Engineering and Power Technology
• Public URL: https://nottingham-repository.worktribe.com/output/5269369
• Publisher URL: https://www.sciencedirect.com/science/article/abs/pii/S1359431120336280?via%3Dihub
• Additional Information: This article is maintained by: Elsevier; Article Title: Polydispersed droplet spectrum and exergy analysis in wet steam flows using method of moments; Journal Title: Applied Thermal Engineering; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.applthermaleng.2020.116148; Content Type: article; Copyright: © 2020 Elsevier Ltd. All rights reserved.