Modelling a molten salt thermal energy system: A validation study

Jari Lappalainen, Elina Hakkarainen, Teemu Sihvonen, Margarita M. Rodríguez-García, Ville Alopaeus

    Research output: Contribution to journalArticleResearchpeer-review

    • 1 Citations

    Abstract

    Thermal energy storage (TES) plays a crucial role improving the efficiency of solar power utilization. Molten salt (MS) has gained a strong position as a thermal fluid in applications where solar power is stored and used overnight to provide dispatchable energy production. Novel process and operating concepts are being developed for TES systems that require reliable engineering tools. System-wide dynamic simulation provides a virtual test bench and analysis tool for assisting in process and control design and operational issues. Proper characterization of the thermal fluids in simulation tools is critical for successful simulation studies. In this paper, we report the experimental and modelling work related to counter-current heat exchange and free drainage test runs in CIEMAT's multi-purpose MS test loop at Plataforma Solar de Almería in Spain. We present a general method to define MS and non-condensable gas within a homogeneous pressure-flow solver. We present modelling of an indirect MS TES system connected to a thermal oil loop through TEMA type heat exchangers, model calibration with half of the experimental data, and finally, validation simulations against rest of the data. All these experimental data are previously unpublished. The model predicts the system behaviour with good agreement regarding temperatures, pressures, flow rates and liquid levels. The simulations suggest that the heat exchangers’ shell sides suffer from trapped non-condensable gas which significantly affects heat transfer, heat loss to ambient air and hydrodynamic losses. Our results contribute to thermal-hydraulic, system-wide modelling and simulation of MS processes. Furthermore, the results have practical implications for MS TES facilities with respect to system design, analysis and operation.
    LanguageEnglish
    Pages126-145
    Number of pages20
    JournalApplied Energy
    Volume233-234
    DOIs
    Publication statusPublished - Jan 2019
    MoE publication typeNot Eligible

    Fingerprint

    Thermal energy
    Molten materials
    Salts
    salt
    Energy storage
    modeling
    simulation
    energy
    solar power
    Solar energy
    Heat exchangers
    Fluids
    fluid
    countercurrent
    Heat losses
    Gases
    gas
    ambient air
    Drainage
    heat transfer

    Keywords

    • Concentrated solar power
    • Dynamic simulation
    • Heat exchanger
    • Molten salt
    • Thermal energy storage
    • Thermal hydraulics

    OKM Publication Types

    • A1 Refereed journal article

    OKM Open Access Status

    • 0 Not Open Access

    ASJC Scopus subject areas

    • Building and Construction
    • Energy(all)
    • Mechanical Engineering
    • Management, Monitoring, Policy and Law

    Cite this

    Lappalainen, Jari ; Hakkarainen, Elina ; Sihvonen, Teemu ; Rodríguez-García, Margarita M. ; Alopaeus, Ville. / Modelling a molten salt thermal energy system : A validation study. In: Applied Energy. 2019 ; Vol. 233-234. pp. 126-145.
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    abstract = "Thermal energy storage (TES) plays a crucial role improving the efficiency of solar power utilization. Molten salt (MS) has gained a strong position as a thermal fluid in applications where solar power is stored and used overnight to provide dispatchable energy production. Novel process and operating concepts are being developed for TES systems that require reliable engineering tools. System-wide dynamic simulation provides a virtual test bench and analysis tool for assisting in process and control design and operational issues. Proper characterization of the thermal fluids in simulation tools is critical for successful simulation studies. In this paper, we report the experimental and modelling work related to counter-current heat exchange and free drainage test runs in CIEMAT's multi-purpose MS test loop at Plataforma Solar de Almer{\'i}a in Spain. We present a general method to define MS and non-condensable gas within a homogeneous pressure-flow solver. We present modelling of an indirect MS TES system connected to a thermal oil loop through TEMA type heat exchangers, model calibration with half of the experimental data, and finally, validation simulations against rest of the data. All these experimental data are previously unpublished. The model predicts the system behaviour with good agreement regarding temperatures, pressures, flow rates and liquid levels. The simulations suggest that the heat exchangers’ shell sides suffer from trapped non-condensable gas which significantly affects heat transfer, heat loss to ambient air and hydrodynamic losses. Our results contribute to thermal-hydraulic, system-wide modelling and simulation of MS processes. Furthermore, the results have practical implications for MS TES facilities with respect to system design, analysis and operation.",
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    Modelling a molten salt thermal energy system : A validation study. / Lappalainen, Jari; Hakkarainen, Elina; Sihvonen, Teemu; Rodríguez-García, Margarita M.; Alopaeus, Ville.

    In: Applied Energy, Vol. 233-234, 01.2019, p. 126-145.

    Research output: Contribution to journalArticleResearchpeer-review

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    AU - Lappalainen, Jari

    AU - Hakkarainen, Elina

    AU - Sihvonen, Teemu

    AU - Rodríguez-García, Margarita M.

    AU - Alopaeus, Ville

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    KW - Dynamic simulation

    KW - Heat exchanger

    KW - Molten salt

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    KW - Thermal hydraulics

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    JF - Applied Energy

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