NUMERICAL MODELING OF THE DESUBLIMATION OF CO2

Abstract

. Desublimation of CO 2 from a point source through direct contact with a cryogenic liquid is a promising approach to capture carbon. This study presents the results of a 3D numerical model of the desublimation process of CO 2 onto a solid surface. Due to its high triple point pressure (~5.2 bar), CO 2 converts to solid directly from the gas phase (i.e., desublimates) if cooled sufficiently at around atmospheric pressure. Desublimation phenomena on the surface has been modeled using a user-defined function (UDF) based on the diffusion boundary layer model implemented in CONVERGE. Preliminary work on the development of a 3D CO 2 desublimation model is presented here with two different test cases: one with a single isothermal, solid, spherical surface; and the other with multiple solid isothermal spheres stacked vertically. The results show that the rate of desublimation is dependent on the number of spheres in the domain, the concentration of the point source, and the temperature of the spherical surface. The resulting decrease in the local molar concentration of CO 2 between the surface of the static sphere and the immediate gas phase in the domain suggests desublimation. This was supported by the temperature difference at the same points in the domain. The numerical formulation of the desublimation model is validated analytically through the solid-vapor equations of state and the energy, mass, and species balance. The developed model will be used in future assessment of the desublimation-based cryogenic carbon capture system, post-experimental validation