Simulation numérique du transfert couple chaleur- humidité dans un milieu poreux application a la caractérisation thermique des bois tropicaux

Abstract

The measurement of the thermal properties of porous materials such as wood has a major disadvantage related to their behavior with respect to the humidity of the ambient air. The porous material chosen in this work is a species of heavy wood commonly called Bilinga whose scientific name is Nauclea diderrichii, it has a high density, it is used for the construction of frameworks, ground and fences. The chosen species has a good durability with respect for the different types of fungi. Bilinga can be used without preservatives and is difficult to deform during drying. The sample with variable water content is subjected to a heat flux identical to that caused by a parallel hot wire device. To better conduct our study, a coupled heat and mass transfer model is solved numerically by the explicit finite difference method, in transient 1D consideration, under MATLAB. The comparison between the curves obtained from the coupled transfer model and those obtained from the thermal quadrupole model allowed to analyze more precisely the influence of mass transfers on the thermal behavior of this material. The results show that for wood species with less than 11% water content, the fibres are occupied by bound water, the quadrupole model remains valid for the various measurements. Transfer processes evolve faster for low water content compared to high water content. For wood species with more than 35% water content, the saturation point of the fibres has been reached, so it becomes more difficult to make measurements; The water content has a significant influence on heat transfer and therefore cannot be overlooked in different transfer studies