Modeling evaporative emissions from parked gasoline cars based on vehicle carbon canister experiments

A time-step model was constructed to estimate the amount of evaporative emissions from vehicular diurnal breathing loss (DBL) on the basis of fuel adsorption-desorption experiments for several carbon canisters attached to seven gasoline vehicles using a chassis dynamometer. Experimental results showed that the canister's total volatile organic compound (VOC) storage ability is proportional to the canister volume, and a canister's desorption ability strongly depends on the amount of VOC trapped in the canister and the air purge flow rate of each vehicle. These properties were formulated into equations by regression analysis and used with the material balance inside the canister to propose a model for estimating emissions after carbon canister breakthrough, which are a function of a vehicle's driving and parking frequency. The model was applied to DBL experimental results derived from our previous studies to confirm its validity. Better agreement between the model and the previous experimental results was obtained when appropriate parameters were set. The proposed model is expected to contribute to estimating the VOC emission inventory for gasoline vehicles.