Xiao, X, Jia, H, Wen, D orcid.org/0000-0003-3492-7982 et al. (2 more authors) (2023) Experimental investigation of a latent heat thermal energy storage unit encapsulated with molten salt/metal foam composite seeded with nanoparticles. Energy and Built Environment, 4 (1). pp. 74-85. ISSN 2666-1233
Abstract
Molten salt has been widely used in latent heat thermal energy storage (LHTES) system, which can be incorporated into hybrid photovoltaic/thermal solar system to accommodate the built environment. Solar salt (60 wt.% NaNO₃ and 40 wt.% KNO₃) was employed as the phase change materials (PCMs) in this study, and both aluminum oxide (Al₂O₃) nanopowder and metal foam were used to improve the properties of pure solar salt. The synthesis of the salt/metal foam composites seeded with Al₂O₃ nanopowder were performed with the two-step and impregnation methods, and the composite PCMs were characterized morphologically and thermally. Then pure solar salt, the salt/2 wt.% Al₂O₃ nanopowder and salt/copper foam composite seeded with 2 wt.% Al₂O₃ nanopowder were encapsulated in a pilot test rig, respectively, where a heater of 380.0 W was located in the center of the LHTES unit. The charging and discharging processes of the LHTES unit were conducted extensively, whereas the heating temperatures were controlled at 240 °C, 260 °C and 280 °C respectively. Temperature evolutions at radial, angular and axial positions were recorded, and the time-durations and volumetric mean powers during the charging and discharging processes were obtained and calculated subsequently. The results show that physical bonding between Al₂O₃ nanopowder and nitrate molecule has been formed from the morphological pictures together with XRD and FTIR curves. Slight changes are found between the melting/freezing phase change temperatures of the salt/metal foam composites seeded with Al₂O₃ nanopowder and those of pure solar salt, and the specific heats of the salt/Al₂O₃nanopowder composite slightly increase with the addition of Al₂O₃ nanopowder. The time-duration of the charging process for the salt/copper foam composite seeded with Al₂O₃ nanopowder at the heating temperature of 240 °C can be reduced by about 74.0%, compared to that of pure solar salt, indicating that the heat transfer characteristics of the LHTES unit encapsulated with the salt/copper foam composite seeded with Al₂O₃ nanopowder can be enhanced significantly. Consequently, the mean volumetric powers of the charging process were distinctly enhanced, e.g., the volumetric mean power of heat storage can reach 110.76 kW/m³, compared to 31.94 kW/m³ of pure solar salt. However, the additive has little effect on the volumetric mean power of heat retrieval because of the domination of natural air cooling.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2021 Southwest Jiatong University. Publishing services by Elsevier B.V. on behalf of KeAi Communication Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
Keywords: | Solar salt; Aluminium oxide nanopowder; Metal foam; Heat transfer characteristics |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemical & Process Engineering (Leeds) |
Funding Information: | Funder Grant number EU - European Union GA 706788 |
Depositing User: | Symplectic Publications |
Date Deposited: | 16 Feb 2022 15:56 |
Last Modified: | 25 Jun 2023 22:54 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.enbenv.2021.08.003 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:183621 |