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Title: Spatial and temporal modeling of sub- and supercritical thermal energy storage

Abstract

This paper describes a thermodynamic model that simulates the discharge cycle of a single-tank thermal energy storage (TES) system that can operate from the two-phase (liquid-vapor) to supercritical regimes for storage fluid temperatures typical of concentrating solar power plants. State-of-the-art TES design utilizes a two-tank system with molten nitrate salts; one major problem is the high capital cost of the salts (International Renewable Energy Agency, 2012). The alternate approach explored here opens up the use of low-cost fluids by considering operation at higher pressures associated with the two-phase and supercritical regimes. The main challenge to such a system is its high pressures and temperatures which necessitate a relatively high-cost containment vessel that represents a large fraction of the system capital cost. To mitigate this cost, the proposed design utilizes a single-tank TES system, effectively halving the required wall material. A single-tank approach also significantly reduces the complexity of the system in comparison to the two-tank systems, which require expensive pumps and external heat exchangers. A thermodynamic model is used to evaluate system performance; in particular it predicts the volume of tank wall material needed to encapsulate the storage fluid. The transient temperature of the tank is observed to remain hottestmore » at the storage tank exit, which is beneficial to system operation. It is also shown that there is an optimum storage fluid loading that generates a given turbine energy output while minimizing the required tank wall material. Overall, this study explores opportunities to further improve current solar thermal technologies. The proposed single-tank system shows promise for decreasing the cost of thermal energy storage. (C) 2014 Elsevier Ltd. All rights reserved.« less

Authors:
; ; ;
Publication Date:
Sponsoring Org.:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
OSTI Identifier:
1211100
DOE Contract Number:  
DE-AR0000140
Resource Type:
Journal Article
Journal Name:
Solar Energy
Additional Journal Information:
Journal Volume: 103; Journal ID: ISSN 0038-092X
Country of Publication:
United States
Language:
English

Citation Formats

Tse, LA, Ganapathi, GB, Wirz, RE, and Lavine, AS. Spatial and temporal modeling of sub- and supercritical thermal energy storage. United States: N. p., 2014. Web. doi:10.1016/j.solener.2014.02.040.
Tse, LA, Ganapathi, GB, Wirz, RE, & Lavine, AS. Spatial and temporal modeling of sub- and supercritical thermal energy storage. United States. https://doi.org/10.1016/j.solener.2014.02.040
Tse, LA, Ganapathi, GB, Wirz, RE, and Lavine, AS. 2014. "Spatial and temporal modeling of sub- and supercritical thermal energy storage". United States. https://doi.org/10.1016/j.solener.2014.02.040.
@article{osti_1211100,
title = {Spatial and temporal modeling of sub- and supercritical thermal energy storage},
author = {Tse, LA and Ganapathi, GB and Wirz, RE and Lavine, AS},
abstractNote = {This paper describes a thermodynamic model that simulates the discharge cycle of a single-tank thermal energy storage (TES) system that can operate from the two-phase (liquid-vapor) to supercritical regimes for storage fluid temperatures typical of concentrating solar power plants. State-of-the-art TES design utilizes a two-tank system with molten nitrate salts; one major problem is the high capital cost of the salts (International Renewable Energy Agency, 2012). The alternate approach explored here opens up the use of low-cost fluids by considering operation at higher pressures associated with the two-phase and supercritical regimes. The main challenge to such a system is its high pressures and temperatures which necessitate a relatively high-cost containment vessel that represents a large fraction of the system capital cost. To mitigate this cost, the proposed design utilizes a single-tank TES system, effectively halving the required wall material. A single-tank approach also significantly reduces the complexity of the system in comparison to the two-tank systems, which require expensive pumps and external heat exchangers. A thermodynamic model is used to evaluate system performance; in particular it predicts the volume of tank wall material needed to encapsulate the storage fluid. The transient temperature of the tank is observed to remain hottest at the storage tank exit, which is beneficial to system operation. It is also shown that there is an optimum storage fluid loading that generates a given turbine energy output while minimizing the required tank wall material. Overall, this study explores opportunities to further improve current solar thermal technologies. The proposed single-tank system shows promise for decreasing the cost of thermal energy storage. (C) 2014 Elsevier Ltd. All rights reserved.},
doi = {10.1016/j.solener.2014.02.040},
url = {https://www.osti.gov/biblio/1211100}, journal = {Solar Energy},
issn = {0038-092X},
number = ,
volume = 103,
place = {United States},
year = {Thu May 01 00:00:00 EDT 2014},
month = {Thu May 01 00:00:00 EDT 2014}
}