Multiscale Modeling of Drying as a Powerful Extension of the Macroscopic Approach: Application to Solid Wood and Biomass Processing

Abstract

This article is devoted to multiscale approaches of heat and mass transfer in porous media, with particular reference to drying. The macroscopic formulation of coupled heat and mass transfer has been widely used in the past two decades to model and simulate the drying of one single piece of product, including in the case of internal vaporization. However, more often than expected, the macroscopic approach fails. Several examples are proposed here, in which these limitations are addressed by accounting for several scales simultaneously.

Different formulations are briefly presented to allow two spatial scales to be considered concurrently. Then, some simulations of multiscale transfer configurations are proposed:

	drying of a heterogeneous porous medium,
	drying of a stack of timber,
	convective drying of a thick bed of particles, and
	storage of a bed of particles.

Keywords:

• Biomass
• Computational model
• Concurrent coupling
• Drying
• Dual scale
• Porous media
• Wood

ACKNOWLEDGMENTS

As part of the “Pôle Fibres”, this work was partly supported by the “Région Lorraine” and the European Community (FEDER). It was also supported by the French National Research Agency through the ANR projects Torbigap and TransBatiBois.

Notes

This article is an extended and improved content of the keynote lectures presented at the joint conference AFSIA/EFCE (WP drying) organized for the jubilee of Michel Roques (Biarritz, France, May 2007) and at the 16th International Drying Symposium (Hyderabad, India, November 2008).