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A novel approach to thermal storage of direct steam generation solar power systems through two-step heat discharge

Li, Jing; Gao, Guangtao; Kutlu, Cagri; Liu, Keliang; Pei, Gang; Su, Yuehong; Ji, Jie; Riffat, Saffa

Authors

Guangtao Gao

Cagri Kutlu

Keliang Liu

Gang Pei

Yuehong Su

Jie Ji

Saffa Riffat



Abstract

© 2018 Elsevier Ltd Steam accumulators are the only commercial solution for heat storage of direct steam generation (DSG) solar thermal power plants. Current accumulators have low storage capacity as the turbine suffers from inefficient off-design operation during heat discharge, thereby restricting the development of DSG technology. This work presents a novel approach to solving this problem by using two-stage accumulators and steam-organic Rankine cycles (RC-ORC). The system involves unique two-step heat discharge. Heat is initially released via water vaporization in a high temperature accumulator (HTA) to drive the RC-ORC, leading to an HTA temperature drop of approximately 30 °C. Water at a reduced temperature then flows from the HTA to a low temperature accumulator through a heat exchanger and the heat is used only to drive the ORC. Water temperature further drops by 130–190 °C. The fundamentals of the system are illustrated. A comparison with the conventional DSG system is conducted at a nominal power of 10 MW with an accumulator volume of 2500 m3. Thermodynamic performance of the system is investigated. The equivalent payback period (EPP) regarding the use of the second step heat discharge is estimated. Results indicate that the second step heat discharge can increase the storage capacity by 460%, with an EPP of less than 5 years in most cases. Overall, the proposed solution improves the cost-effectiveness of the DSG system.

Citation

Li, J., Gao, G., Kutlu, C., Liu, K., Pei, G., Su, Y., …Riffat, S. (2019). A novel approach to thermal storage of direct steam generation solar power systems through two-step heat discharge. Applied energy, 236, 81-100. https://doi.org/10.1016/j.apenergy.2018.11.084

Journal Article Type Article
Acceptance Date Nov 23, 2018
Online Publication Date Nov 28, 2018
Publication Date Feb 15, 2019
Deposit Date Mar 5, 2021
Publicly Available Date Mar 29, 2024
Journal Applied Energy
Print ISSN 0306-2619
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 236
Pages 81-100
DOI https://doi.org/10.1016/j.apenergy.2018.11.084
Keywords Two-step heat discharge; Two-stage accumulators; Two-stage steam-organic Rankine cycles; Direct steam generation; Wet steam turbine; Equivalent payback period
Public URL https://hull-repository.worktribe.com/output/3602484
Related Public URLs https://nottingham-repository.worktribe.com/output/1357445/a-novel-approach-to-thermal-storage-of-direct-steam-generation-solar-power-systems-through-two-step-heat-discharge

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