# Spectrally resolved calculation of thermal radiation penetration into liquid n-heptane in pool fires

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**Spectrally resolved calculation of thermal radiation penetration into liquid n-heptane in pool fires.** / Isojärvi, Teemu; Bordbar, Hadi; Hostikka, Simo.

Research output: Contribution to journal › Article › Scientific › peer-review

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*International Journal of Heat and Mass Transfer*, vol. 127, pp. 1101-1109. https://doi.org/10.1016/j.ijheatmasstransfer.2018.08.108

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*International Journal of Heat and Mass Transfer*,

*127*, 1101-1109. https://doi.org/10.1016/j.ijheatmasstransfer.2018.08.108

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TY - JOUR

T1 - Spectrally resolved calculation of thermal radiation penetration into liquid n-heptane in pool fires

AU - Isojärvi, Teemu

AU - Bordbar, Hadi

AU - Hostikka, Simo

PY - 2018/12/1

Y1 - 2018/12/1

N2 - The radiative heat transfer in a volatile hydrocarbon pool fire was investigated by obtaining the transmittance of infrared radiation through fuel (n-heptane) layers of different depths. The incident radiation spectrum was assumed to be either the same as a spectrum obtained experimentally for a 2 meter pool fire, or to be a Planck distribution corresponding to the approximate flame temperature. The transmittances were calculated by integrating either the single-ray Lambert-Beer formula, the two-flux method or the analytical plane-parallel monochromatic/gray solution of the radiative transfer equationover wavelength, using the liquid spectral absorption coefficients found in literature. The obtained results are validated against earlier measurements, and the possibility of calculating them with significantly less computation time by using a k-distribution method was investigated. The results managed to replicate the measured heat flux values in the liquid with a fractional error of only about 5% being attainable even with a 3-point quadrature method. The use of the k-distribution, more known and used in gas phase thermal radiation calculations, significantly speeds up the calculations. It was found out that in thecalculation of total transmitted fractions of radiation, the flame spectrum can be approximated with a Planck distribution of an appropriate temperature.

AB - The radiative heat transfer in a volatile hydrocarbon pool fire was investigated by obtaining the transmittance of infrared radiation through fuel (n-heptane) layers of different depths. The incident radiation spectrum was assumed to be either the same as a spectrum obtained experimentally for a 2 meter pool fire, or to be a Planck distribution corresponding to the approximate flame temperature. The transmittances were calculated by integrating either the single-ray Lambert-Beer formula, the two-flux method or the analytical plane-parallel monochromatic/gray solution of the radiative transfer equationover wavelength, using the liquid spectral absorption coefficients found in literature. The obtained results are validated against earlier measurements, and the possibility of calculating them with significantly less computation time by using a k-distribution method was investigated. The results managed to replicate the measured heat flux values in the liquid with a fractional error of only about 5% being attainable even with a 3-point quadrature method. The use of the k-distribution, more known and used in gas phase thermal radiation calculations, significantly speeds up the calculations. It was found out that in thecalculation of total transmitted fractions of radiation, the flame spectrum can be approximated with a Planck distribution of an appropriate temperature.

KW - spectral radiation

KW - k-distribution

KW - liquid n-heptane

KW - pool fire

KW - numerical modeling

UR - http://www.scopus.com/inward/record.url?scp=85052503783&partnerID=8YFLogxK

U2 - 10.1016/j.ijheatmasstransfer.2018.08.108

DO - 10.1016/j.ijheatmasstransfer.2018.08.108

M3 - Article

VL - 127

SP - 1101

EP - 1109

JO - International Journal of Heat and Mass Transfer

JF - International Journal of Heat and Mass Transfer

SN - 0017-9310

ER -

ID: 27372789