Development of inverse methods for determining thermophysical and radiative properties of high-temperature fibrous materials

Matthews, L. K.; Viskanta, R.; Incropera, F. P.

doi:10.1016/0017-9310(84)90022-x

Cited by 30 publications

(5 citation statements)

References 7 publications

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“…For conduction only, the evaluated heat fluxes changed less than 0.2% for a refinement from 32 3 cells to 92 3 cells. The refinement of the mesh for the coupled heat transfer is computationally more expensive.…”

Section: Spatial Discretizationmentioning

confidence: 96%

“…Details of volume averaging theory applied to problems relevant in heat and mass transfer are described in [1]. Effective properties can be determined experimentally [2,3] or through simulations. As the effective properties significantly depend on the geometry of the porous media, accurate computational approaches directly incorporate the exact morphology using, for example, computed tomography of the materials of interest [4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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Numerical quantification of coupling effects for radiation-conduction heat transfer in participating macroporous media: Investigation of a model geometry

Perraudin

Haussener

2017

International Journal of Heat and Mass Transfer

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a b s t r a c tRadiative-conductive heat transfer in porous media is usually investigated by decoupling the heat transfer modes and solving the volume-averaged continuum equations using effective transport properties. However, both modes are naturally coupled and coupling effects might significantly affect the results. We aim at providing quantitative understanding of the coupling effects occurring in a model geometry. This is an important first step towards improving the accuracy of heat transfer predictions in engineering applications.We developed a numerical method using a structured mesh, cell centered finite volumes and Monte Carlo ray tracing techniques in order to simulate the 3-dimensional and unsteady coupled radiativeconductive heat transfer in semitransparent macroporous media. We have optimized the numerical method with regards to memory and computational requirements leading to optimal performance and allowing to perform a parameter variation study for various steady state cases.We conducted a parameter study considering different optical and thermal material properties and boundary conditions in order to quantify the coupling effect between conduction and radiation, and to demonstrate its dependencies. In terms of thermal properties, it was found that the ratio of bulk thermal conductivities is governing the coupling effect. A distinct peak at a given conductivity ratio was found. The influence of optical properties is discussed in details. It was found that a significant coupling effect exists, reaching up to 15% of the total thermal heat flux.The verified modeling framework in conjunction with our non-dimensionalization offers a tool to investigate the importance of radiation-conduction coupling in a quantitative manner. It is an important step towards understanding the detailed mechanisms of radiation and conduction coupling and provides engineering guidelines on the importance of these effects.

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Section: Spatial Discretizationmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Numerical quantification of coupling effects for radiation-conduction heat transfer in participating macroporous media: Investigation of a model geometry

Perraudin

Haussener

2017

International Journal of Heat and Mass Transfer

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“…Nevertheless only a limited amount of work is available on the inverse problem in this field [1,2,3].…”

Section: Introductionmentioning

confidence: 99%

Flash experiment on a semitransparent material: interest of a reduced model

Lazard

Silva

Maillet

et al. 2001

Inverse Problems in Engineering

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The subject deals with a reduced model of the conductiveradiative transient transfer in a participating medium. The accuracy of the analytical solution based on the well-known two-flux approximation and expressed with global radiative coefficients is tested in the case of sharp thermal excitation by a heat pulse on the front face of anisotropically scattering media. A very good agreement is achieved compared with numerical and analytical simulations involving high forward scattering, linear anisotropic scattering or Rayleigh scattering. This reduced model is then used in the inverse approach in order to determine the intrinsic diffusivity of semitransparent media. INTRODUCTIONThe increasing use of glasses, insulated foams, polymers in new technological products forced gradually the heat transfer community to take an interest in the study of combined radiative and conductive transfer in semitransparent media. Nevertheless only a limited amount of work is available on the inverse problem in this field [1,2,3].Concerning the thermal diffusivity measurement, a lot of authors tried to extend the use of the flash method, first developed for opaque materials [4], to semitransparent media [5]. In those participating media, the measured diffusivity is an apparent one. It takes both conductive and radiative transfers into account. In order to obtain the phonic diffusivity, which is an intrinsic parameter, it is necessary to build a model including both radiative and conductive effects. As a consequence, the number of parameters increases. The aim of this study does not consist in evaluating all the parameters: it will be utopian with only one information namely the evolution of the rear face temperature. We rather try to show that a reduced model is able to reproduce the thermal behavior of absorbing, emitting and anisotropically scattering in a realistic way. More specifically, it allows to reach the phonic diffusivity which is a significant parameter for the engineering calculations.

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“…Radiative properties of fibrous media used as thermal insulation, mostly low-density media, have long been investigated through both theoretical modeling [ [9,82,88,89]. These authors mostly used numerical solutions of the RTE by the discrete ordinates method combined with inverse approaches based on the Gauss linearization method to determine each of the unknown parameters.…”

Section: Examples Of Dispersed Media and Property Determination Anisomentioning

confidence: 99%

Thermal Radiative Properties of Complex Media: Theoretical Prediction Versus Experimental Identification

Sacadura

2011

Heat Transfer Engineering

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In many engineering applications and natural phenomena, thermal radiation interacts with complex media composed of dispersed phases that may be of different type: solid/solid, solid/gas, or liquid/gas. Most of them are semitransparent media that emit, absorb, and scatter thermal radiation. Heat transfer by combined radiation with conduction or convection in such media is a problem of high practical importance, mostly in situations where radiation is a dominant mode. Improvement of thermal performance of such materials or of the manufacturing processes that involve these media requires the availability of efficient methods (i) for radiative transfer modeling, and (ii) to predict and to experimentally determine the thermophysical properties intended to feed the models. This paper is focused on radiative properties assessment. After a brief overview of the materials and properties of interest, the emphasis is put on methodology of property investigation combining both theoretical prediction and experimental identification. Examples related to different particulate media are presented, showing recent advances and needs for further investigation.

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Development of inverse methods for determining thermophysical and radiative properties of high-temperature fibrous materials

Cited by 30 publications

References 7 publications

Numerical quantification of coupling effects for radiation-conduction heat transfer in participating macroporous media: Investigation of a model geometry

Numerical quantification of coupling effects for radiation-conduction heat transfer in participating macroporous media: Investigation of a model geometry

Flash experiment on a semitransparent material: interest of a reduced model

Thermal Radiative Properties of Complex Media: Theoretical Prediction Versus Experimental Identification

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