An Investigation into the Influence of LPG (Autogas) Composition on the Exhaust Emissions and Fuel Consumption of 3 Bi-Fuelled Renault Vehicles 961170

Studies using a bi-fuelled (autogas/gasoline) Renault Laguna vehicle meeting °the 1996 European exhaust emission legislation has demonstrated that over the European test cycle at 25°C the LPG operated vehicle provides substantial benefits of reduced emissions compared to unleaded reference gasoline. At lower test temperatures (i.e. 5°C) even larger reduction in emissions have been observed. Lower CO (up to 95% at -5°C and 65% at 25°C), HC (90% at -5°C and 40% at 25°C) emissions and lower ozone HC reactivity have been observed and could all offer significant environmental air-quality benefits for LPG.Various autogas mixtures have been tested including 70/30, 30/70 and 49/30/21 (% mass propane / butane / propene). Results show that NOx emissions for this vehicle appear dependent on autogas composition. The two gas mixtures containing only 30% butane gave about 50% more NOx at +25°C than the 70% butane autogas mixture. At -5°C the gas containing 21% propene gives higher NOx emissions (by ∼30%) than the two gases without unsaturated components. These trends were similar over the ECE 1+2, 3+4 and EUDC phases of the European drive cycle. At -5°C all the gas mixtures show a NOx reduction compared to the reference gasoline. Benzene and 1,3 butadiene emissions (2 of the US EPA air-toxics) were also very low (