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Entropy generation and exergy destruction in condensing steam flow through turbine blade with surface roughness

Ding, Hongbing; Li, Yiming; Lakzian, Esmail; Wen, Chuang; Wang, Chao

Authors

Hongbing Ding

Yiming Li

Esmail Lakzian

CHUANG WEN Chuang.Wen@nottingham.ac.uk
Marie Sklodowska-Curie Individual Fellow

Chao Wang



Abstract

In the steam turbine, the wetness loss due to vapor condensation is one of the most crucial losses at low-pressure stage. This study focused on entropy generation and exergy destruction of condensing steam flow in turbine blade with the roughness. The governing equations including entropy transport equation combined with condensation model, transition SST model and roughness correlation were established and verified by experiments and theory. Flow field behaviors, such as wetness fraction, intermittency and turbulent viscosity distributions, controlled by the deviation angle were obtained to evaluate effects of back pressure ratio and surface roughness. The mass-averaged wetness fraction at outlet was also extracted considering the influence of uneven mass flux. Finally, each part of entropy generation derived from viscous, heat conduction, phase change and aerodynamic losses and exergy destruction ratio were analyzed. Research shows that roughness plays an important part in the intermittency and turbulent viscosity. The mass-averaged wetness fraction at outlet sharply drops with back pressure ratio but slightly decreases with the roughness. With the roughness rising or back pressure dropping, the entropy generation grows resulting in more exergy destruction. The maximum value of the total entropy generation is 84.520 J·kg−1·K−1, corresponding exergy destruction is 25.187 kJ·kg−1 and exergy destruction ratio is 4.43%.

Journal Article Type Article
Publication Date Sep 15, 2019
Journal Energy Conversion and Management
Print ISSN 0196-8904
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 196
Pages 1089-1104
Institution Citation Ding, H., Li, Y., Lakzian, E., Wen, C., & Wang, C. (2019). Entropy generation and exergy destruction in condensing steam flow through turbine blade with surface roughness. Energy Conversion and Management, 196, 1089-1104. doi:10.1016/j.enconman.2019.06.066
DOI https://doi.org/10.1016/j.enconman.2019.06.066
Keywords Fuel Technology; Renewable Energy, Sustainability and the Environment; Energy Engineering and Power Technology; Nuclear Energy and Engineering
Publisher URL https://www.sciencedirect.com/science/article/pii/S019689041930737X

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