摘要

The drying of sewage sludge is a current environmental problem, not sufficiently described in the literature. Hence, the aim of this work is a numerical study of heat and mass transfer under solar drying of residual sludge. This sludge is assimilated to a porous medium and exposed to a forced convection laminar flow within a horizontal channel. The processes of transfer in the channel and in the porous medium are respectively described by the classical equations of forced convection and of the Darcy–Brinkman–Forchheimer model. The implicit finite difference method is used to discretize the governing differential equation system. The algebraic systems obtained are solved using the Gauss, Thomas, and Gauss–Seidel algorithms. To determine the drying rate, we associate a drying kinetics model. We particularly studied the effects of solar radiation intensity and ambient air temperature on the space–time evolution of temperature, velocity, and mass traction at the ambient air–porous medium interface. Moreover, the evolutions of Nusselt and Sherwood numbers are represented to characterize the processes of transfer at the sludge surface. This work is completed by a drying kinetics study. Indeed, we represent the space–time evolution of the drying rate and water content.