Experimental adsorption and desorption characterization of a gasoline-fueled vehicle carbon canister for European application filled with n-butane and nitrogen mixtures

Abstract

The evaporative emission control system (EVAP system) is the most commonly used strategy to limit the unburned petrol vapor emissions from a gasoline-fueled vehicle fuel tank, in order to comply with the international regulations on Volatile Organic Compounds (VOCs) emission. A carbon canister is used to collect and store the gasoline vapors generated in the tank, then it is purged by the engine intake manifold depression and the vapors are burned in the engine along with the fresh charge. In this activity, a 1.0 L carbon canister for European gasoline vehicles, provided by FCA, has been used for an experimental analysis, in order to characterize its adsorption and desorption behavior. A standard mixture of n-butane and nitrogen (40 g/h of n-butane, 50% vol. with nitrogen) has been used for loading the canister to breakthrough (2 g); canister purging has been performed with 3000 bed volumes of nitrogen flux at 25 L/min. Tests have been performed in FCA laboratories, at the Pomigliano Technical Center. Canister mass gain has been measured during the tests and after each test with a precision weight scale. Internal temperatures have also been measured by K-type thermocouples placed inside the carbon bed; due to the adsorption process, bed temperatures can reach 70 °C. After several tests, results on mass gain show an “aging” trend of the activated carbons.