As the leading source of air pollution in large urban centres, the automobile is at the source of health problems such as coughing, sore throats, headaches and eye irritation. It also serves as an aggravating factor in asthma and respiratory illnesses. Aside from toxic emission gases which are reduced by catalytic converters, pollution also stems from the evaporation of fuel in the tank and the fuel circuit. There is a targeted means of capturing these emissions and recycling them into the injection system: the canister. Placed in the centre of the device, activated carbons are the determining factor in the efficiency of the canister, on the condition that their density, adsorption capacity, and mechanical setting are precisely adjusted.
Reducing atmospheric emissions
Issues:
Targeted compounds:
Volatile organic compounds
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Hydrocarbons
Reducing the CO2 emissions
Solutions :
Used for more than twenty years in the United States, the canister is now mandatory on all new European automobiles. It involves a system designed to trap fuel vapours in order to cycle them back to the engine.
It is comprised of a filter containing activated carbon, which adsorbs the fuel vapours that escape from the tank, particularly when the motor is stopped. When triggered by an onboard electronic control system, a gase flow desorbs the vapours. Heavily loaded with hydrocarbons, this gase flow is then recycled into the engine's air injection system, thus reducing loss through evaporation by about 90%. The performance of activated carbons used in this case is measured by the difference between the adsorption volume and the desorption volumes (BWC: Butane Working Capacity).
PICA has been a pioneer in this field. Since its first sales on the American market in 1973, it has followed a progression of constant improvements aiming mainly to reduce the loss of capacity in activated carbons, to accept larger and larger adsorption volumes, and to adapt to new types of canister.
Activated carbons currently offered by PICA for this purpose are wood-based. They are characterized by a high adsorbent power and very light weight in relation to other carbons available on the market. The choice of activated carbon made by PICA also minimizes the quantity of fuel remaining in the canister after the purge.