Large-cell model of radiation heat transfer in multiphase flows typical for fuel–coolant interaction

International Journal of Heat and Mass Transfer

2016

A solution for the complete problem of attenuation of fire radiation by water mist is presented. This solution is based on simplified approaches for the spectral radiative properties of water droplets, the radiative transfer in the absorbing and scattering mist, and transient heat transfer taking into account partial evaporation of water mist. A computational study of the conventional model problem indicates the role of the main parameters and enables one to formulate some recommendations to optimize possible engineering solutions. The method developed is also applied to more realistic case study of a real fire. It is suggested to decrease the size of supplied water droplets with the distance from the irradiated surface of the mist layer. The advantage of this engineering solution is confirmed by numerical calculations. Potential possibility of microwave monitoring of water mist parameters is analyzed on the basis of Mie theory calculations.

Section: Radiative Transfer Modelmentioning

confidence: 86%

Section: Spectral Properties Of Water Dropletsmentioning

confidence: 99%

A simplified model for the shielding of fire thermal radiation by water mists

International Journal of Heat and Mass Transfer

2016

“…It is assumed that there is no radiative transfer between the neighboring layers. As a result, the radiation model is z -direction is similar to the Large-Cell Model suggested in (Dombrovsky, 2007) and employed in papers (Dombrovsky, 2009;Dombrovsky et al, 2009). …”

Section: Radiative Transfer Modelmentioning

confidence: 87%

Shielding of Fire Radiation With the Use of Multi-Layered Water Mist Curtains: Preliminary Estimates

2016

Comput Thermal Scien

Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Publisher's statement:Published version : http://www.dl.begellhouse.com/journals/648192910890cd0e,1e6659ad3a62cac6,38f69f0e2 e9039e0.html A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription.For more information, please contact the WRAP Team at: wrap@warwick.ac.uk SHIELDING OF FIRE RADIATION WITH THE USE OF MULTI-LAYERED WATER MIST CURTAINS: PRELIMINARY ESTIMATES

“…It should be recalled that monodisperse approximation is inapplicable for thermal radiation calculations in the case of a strong difference in behaviour of particles of different size. The known examples are: the thermal radiation of particles in plasma spraying [33][34][35][36], the radiation from two-phase combustion products in exhaust plumes of aluminized-propellant rocket engines [37,38], and the radiative cooling of core melt droplets in nuclear fuel-coolant interaction [39,40]. Fortunately, the subsequent calculations showed that it is not the case for the problem under consideration and the monodisperse approximation is really applicable.…”

Section: Infrared Properties Of Water Dropletsmentioning

confidence: 99%

An infrared scattering by evaporating droplets at the initial stage of a pool fire suppression by water sprays

Infrared Physics & Technology

2018

h i g h l i g h t sAn initial stage of a pool fire suppression is considered. The motion, heating, and evaporation of water droplets are calculated. Focusing of evaporating water droplets in local regions is obtained. A strong infrared scattering by small water droplets is analyzed. The spectral region of a significant infrared scattering is determined. a r t i c l e i n f o b s t r a c tThe computational analysis of downward motion and evaporation of water droplets used to suppress a typical transient pool fire shows local regions of a high volume fraction of relatively small droplets. These droplets are comparable in size with the infrared wavelength in the range of intense flame radiation. The estimated scattering of the radiation by these droplets is considerable throughout the entire spectrum except for a narrow region in the vicinity of the main absorption peak of water where the anomalous refraction takes place. The calculations of infrared radiation field in the model pool fire indicate the strong effect of scattering which can be observed experimentally to validate the fire computational model.