Multi-dimensional CFD simulation of adsorption/desorption processes in carbon canister

The carbon canister is an important component of an automobile fuel system in controlling the evaporative emission of gasoline vapor. A careful study of the adsorption/desorption processes in a carbon canister can provide useful guidance in optimizing canister design. In the present work, multi-dimensional, time-accurate simulations of adsorption/desorption processes in carbon canisters have been conducted using Computation Fluid Dynamics (CFD) software FLUENT, with User Defined Functions (UDF) developed and added to the software.; Two-dimensional carbon dioxide adsorption/desorption within a simplified axisymmetric geometry was first simulated. Comparisons were made with reference results to verify the model, and variables such as adsorption amount, adsorbate mole fraction, fluid phase and carbon bed temperatures, velocity and breakthrough curve are analyzed. Three-dimensional production canister was then simulated for carbon dioxide adsorption, and three-dimensional characteristics were observed. The Langmuir isotherm and linear driving force model were used in the simulations.; As a surrogate for gasoline vapor, n-butane adsorption/desorption within a simple two-dimensional geometry was also studied using the Dubinin-Polanyi adsorption potential model and linear driving force model. Comparisons were made to similar reference results with good agreement noted.; Effects of different inlet adsorbate concentrations on adsorption and different initial carbon bed contamination conditions on desorption were studied in both the carbon dioxide and n-butane adsorption/desorption simulations. Meaningful conclusions were drawn and further work is suggested for future studies.