TY - JOUR
T1 - Optimal porosity distribution of fibrous insulation
AU - Du, Ning
AU - Fan, Jintu
AU - Wu, Huijun
AU - Sun, Weiwei
PY - 2009/9
Y1 - 2009/9
N2 - The porosity of fibrous materials is an important factor to their insulating performance. This paper considers the optimal porosity distribution of non-uniform fibrous porous medias for thermal insulation. Heat flow through the fibrous porous media is described by a coupled conduction-radiation heat transfer model which is numerically solved by using Finite Volume Method, and the optimal porosity distribution corresponding to the minimum total heat transfer is derived by applying a BFGS quasi-Newton optimization procedure. Variable analysis shows that the optimal porosity distribution is typically piecewise in conductive heat transfer dominated porous medium. For practical reasons, the change of porosity distribution across the thickness of the fibrous porous media may need to be continuous. To derive such a continuous optimal porosity distribution, a small penalty item should be introduced into the objective function. The study shows that, a continuous optimal porosity distribution generally has relatively high porosity at both boundaries and relatively low porosity in the centre region. The optimal distribution depends on many factors such as fibre radius, fibre emissivity, temperature difference, and overall mean porosity. © 2009 Elsevier Ltd. All rights reserved.
AB - The porosity of fibrous materials is an important factor to their insulating performance. This paper considers the optimal porosity distribution of non-uniform fibrous porous medias for thermal insulation. Heat flow through the fibrous porous media is described by a coupled conduction-radiation heat transfer model which is numerically solved by using Finite Volume Method, and the optimal porosity distribution corresponding to the minimum total heat transfer is derived by applying a BFGS quasi-Newton optimization procedure. Variable analysis shows that the optimal porosity distribution is typically piecewise in conductive heat transfer dominated porous medium. For practical reasons, the change of porosity distribution across the thickness of the fibrous porous media may need to be continuous. To derive such a continuous optimal porosity distribution, a small penalty item should be introduced into the objective function. The study shows that, a continuous optimal porosity distribution generally has relatively high porosity at both boundaries and relatively low porosity in the centre region. The optimal distribution depends on many factors such as fibre radius, fibre emissivity, temperature difference, and overall mean porosity. © 2009 Elsevier Ltd. All rights reserved.
KW - Conduction
KW - Insulation
KW - Optimization
KW - Porosity
KW - Porous media
KW - Radiation
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U2 - 10.1016/j.ijheatmasstransfer.2009.03.067
DO - 10.1016/j.ijheatmasstransfer.2009.03.067
M3 - RGC 21 - Publication in refereed journal
SN - 0017-9310
VL - 52
SP - 4350
EP - 4357
JO - International Journal of Heat and Mass Transfer
JF - International Journal of Heat and Mass Transfer
IS - 19-20
ER -