Heat Transport in Unsaturated Zone Thermal Energy Storage: Analysis with Two-Phase and Single-Phase Models

A. Niemi, Terhi Kling, M. Kangas, M. Ettala

    Research output: Contribution to journalArticleScientificpeer-review

    5 Citations (Scopus)

    Abstract

    We analyze a field experiment where ambient air is injected into the soil during the summer and extracted again during the winter. A multiphase model accounting for the conductive transport as well as the convective transport with the moving liquid and gas phases is used along with a more simplified single-phase model where the convective transport is due to the gas alone. The latter model also accounts for subzero wintertime temperatures. The multiphase model captures well both the seasonal variations and the actual test sequence, the main calibration being in the adjustment of medium permeabilities based on the observed pressure responses. The effect of the injection pump on the temperature and humidity of the injection air needs to be known accurately. Taking into account the humidity of the injection air explicitly instead of using humidity-corrected enthalpy values also has an effect. The effect of various humidity and specific enthalpy assumptions is of the order of 1–1.5°C, while ignoring the wintertime subzero temperatures has an effect of 1–2°C. These differences are of the same order of magnitude as the heterogeneity-introduced differences in field data. Using the simplified single-phase model typically appears to cause a difference of 1–2°C, but can yield an even higher deviation of the order of 3–4°C.
    Original languageEnglish
    Pages (from-to)67-88
    Number of pages26
    JournalTransport in Porous Media
    Volume51
    Issue number1
    DOIs
    Publication statusPublished - 2003
    MoE publication typeA1 Journal article-refereed

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    Thermal energy
    Energy storage
    Atmospheric humidity
    Enthalpy
    Air
    Gases
    Temperature
    Hot Temperature
    Pumps
    Calibration
    Soils
    Liquids
    Experiments

    Cite this

    @article{c896e2c2cc834f129cd38fa4928c6d58,
    title = "Heat Transport in Unsaturated Zone Thermal Energy Storage: Analysis with Two-Phase and Single-Phase Models",
    abstract = "We analyze a field experiment where ambient air is injected into the soil during the summer and extracted again during the winter. A multiphase model accounting for the conductive transport as well as the convective transport with the moving liquid and gas phases is used along with a more simplified single-phase model where the convective transport is due to the gas alone. The latter model also accounts for subzero wintertime temperatures. The multiphase model captures well both the seasonal variations and the actual test sequence, the main calibration being in the adjustment of medium permeabilities based on the observed pressure responses. The effect of the injection pump on the temperature and humidity of the injection air needs to be known accurately. Taking into account the humidity of the injection air explicitly instead of using humidity-corrected enthalpy values also has an effect. The effect of various humidity and specific enthalpy assumptions is of the order of 1–1.5°C, while ignoring the wintertime subzero temperatures has an effect of 1–2°C. These differences are of the same order of magnitude as the heterogeneity-introduced differences in field data. Using the simplified single-phase model typically appears to cause a difference of 1–2°C, but can yield an even higher deviation of the order of 3–4°C.",
    author = "A. Niemi and Terhi Kling and M. Kangas and M. Ettala",
    year = "2003",
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    language = "English",
    volume = "51",
    pages = "67--88",
    journal = "Transport in Porous Media",
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    Heat Transport in Unsaturated Zone Thermal Energy Storage : Analysis with Two-Phase and Single-Phase Models. / Niemi, A.; Kling, Terhi; Kangas, M.; Ettala, M.

    In: Transport in Porous Media, Vol. 51, No. 1, 2003, p. 67-88.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - Heat Transport in Unsaturated Zone Thermal Energy Storage

    T2 - Analysis with Two-Phase and Single-Phase Models

    AU - Niemi, A.

    AU - Kling, Terhi

    AU - Kangas, M.

    AU - Ettala, M.

    PY - 2003

    Y1 - 2003

    N2 - We analyze a field experiment where ambient air is injected into the soil during the summer and extracted again during the winter. A multiphase model accounting for the conductive transport as well as the convective transport with the moving liquid and gas phases is used along with a more simplified single-phase model where the convective transport is due to the gas alone. The latter model also accounts for subzero wintertime temperatures. The multiphase model captures well both the seasonal variations and the actual test sequence, the main calibration being in the adjustment of medium permeabilities based on the observed pressure responses. The effect of the injection pump on the temperature and humidity of the injection air needs to be known accurately. Taking into account the humidity of the injection air explicitly instead of using humidity-corrected enthalpy values also has an effect. The effect of various humidity and specific enthalpy assumptions is of the order of 1–1.5°C, while ignoring the wintertime subzero temperatures has an effect of 1–2°C. These differences are of the same order of magnitude as the heterogeneity-introduced differences in field data. Using the simplified single-phase model typically appears to cause a difference of 1–2°C, but can yield an even higher deviation of the order of 3–4°C.

    AB - We analyze a field experiment where ambient air is injected into the soil during the summer and extracted again during the winter. A multiphase model accounting for the conductive transport as well as the convective transport with the moving liquid and gas phases is used along with a more simplified single-phase model where the convective transport is due to the gas alone. The latter model also accounts for subzero wintertime temperatures. The multiphase model captures well both the seasonal variations and the actual test sequence, the main calibration being in the adjustment of medium permeabilities based on the observed pressure responses. The effect of the injection pump on the temperature and humidity of the injection air needs to be known accurately. Taking into account the humidity of the injection air explicitly instead of using humidity-corrected enthalpy values also has an effect. The effect of various humidity and specific enthalpy assumptions is of the order of 1–1.5°C, while ignoring the wintertime subzero temperatures has an effect of 1–2°C. These differences are of the same order of magnitude as the heterogeneity-introduced differences in field data. Using the simplified single-phase model typically appears to cause a difference of 1–2°C, but can yield an even higher deviation of the order of 3–4°C.

    U2 - 10.1023/A:1021280408281

    DO - 10.1023/A:1021280408281

    M3 - Article

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    JO - Transport in Porous Media

    JF - Transport in Porous Media

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