Abstract:

To reveal the flow structure, mass transfer and solid surface morphology in the solid dissolution process by considering unsteady natural convection, a two-dimensional mathematical model of solid-liquid dissolution process was established based on theories of dissolution kinetics and mass transfer. The finite element software COMSOL was used to investigate the effect of Rayleigh number on the flow, mass transfer and solid surface morphology. The results showed that the method might well capture the interface motion and position caused by dissolution, and obtain the propagations of flow structure and mass transfer. At a low Rayleigh number(10⁴), viscose force is generally more dominant than buoyancy force and diffusion is the principal mode of mass transfer whereas at a higher Rayleigh number, convection is the dominant mass transfer mechanism. As a result, natural convection significantly enhanced mass transfer, and led to nonlinear dissolution. The solid surface morphology depended not only on Rayleigh number but also time.