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Design of steam condensation temperature for an innovative solar thermal power generation system using cascade Rankine cycle and two-stage accumulators

Gao, Guangtao; Li, Jing; Li, Pengcheng; Cao, Jingyu; Pei, Gang; Dabwan, Yousef N.; Su, Yuehong

Design of steam condensation temperature for an innovative solar thermal power generation system using cascade Rankine cycle and two-stage accumulators Thumbnail


Authors

Guangtao Gao

Jing Li

Pengcheng Li

Jingyu Cao

Gang Pei

Yousef N. Dabwan

YUEHONG SU YUEHONG.SU@NOTTINGHAM.AC.UK
Professor of Thermal Science and Building Technology



Abstract

An innovative solar thermal power generation system using cascade steam-organic Rankine cycle (SORC) and two-stage accumulators has recently been proposed. This system offers a significantly higher heat storage capacity than conventional direct steam generation (DSG) solar power plants. The steam condensation temperature (𝑇2) in the proposed system is a crucial parameter because it affects the SORC efficiency (πœ‚π‘†π‘‚π‘…πΆ) in normal operations and the power conversion of the bottoming organic Rankine cycle (ORC) in the unique heat discharge process. The present study develops a methodology for the design of 𝑇2 with respect to a new indicator, that is, the equivalent heat-to-power efficiency (πœ‚π‘’π‘ž). πœ‚π‘’π‘ž is a compromise between the efficiencies in different operation modes. The effects of main steam temperature (𝑇1), Baumann factor (a), mass of storage water (𝑀𝑀), and ORC working fluid on 𝑇2 are investigated. Results show thatπœ‚π‘’π‘ž is a better indicator than πœ‚π‘†π‘‚π‘…πΆ. The optimum steam condensation temperature (𝑇2,π‘œπ‘π‘‘) that corresponds to the maximum πœ‚π‘’π‘ž (πœ‚π‘’π‘ž,π‘šπ‘Žπ‘₯) is generally higher than that based on the maximum πœ‚π‘†π‘‚π‘…πΆ. 𝑇2,π‘œπ‘π‘‘ reduces as 𝑇1, a, and 𝑀𝑀 decrease.πœ‚π‘’π‘ž,π‘šπ‘Žπ‘₯ rises with the increment of 𝑇1 and the decrement of a and𝑀𝑀. Pentane is a more preferable ORC fluid than benzene and R245fa. The 𝑇2,π‘œπ‘π‘‘ and πœ‚π‘’π‘ž,π‘šπ‘Žπ‘₯ of pentane are, respectively, 139-190 Β°C and 20.93%-24.24%,provided that 𝑇1 ranges between 250Β°C and 270Β°C, a varies from 0.5 to 1.5,and 𝑀𝑀 changes from 500 ton to 1500 ton.

Journal Article Type Article
Acceptance Date Jan 11, 2019
Online Publication Date Feb 5, 2019
Publication Date Mar 15, 2019
Deposit Date Feb 13, 2019
Publicly Available Date Feb 13, 2019
Journal Energy Conversion and Management
Print ISSN 0196-8904
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 184
Pages 389-401
DOI https://doi.org/10.1016/j.enconman.2019.01.067
Keywords Fuel Technology; Renewable Energy, Sustainability and the Environment; Energy Engineering and Power Technology; Nuclear Energy and Engineering
Public URL https://nottingham-repository.worktribe.com/output/1545750
Publisher URL https://www.sciencedirect.com/science/article/pii/S0196890419301190

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