Search Results

The effects of fuel formulation changes on vehicles meeting European Stage 1 (91/441/EEC) and Stage II (94/12/EC) emission limits have been investigated. Vehicles in the Euro Stage II fleet were advanced specification versions of the vehicle models in the Euro Stage I fleet. However, the basic engine blocks and capacity were the same. The observed improvements in emissions were attributed to changes, such as position of the catalyst and lambda sensor, improved fuel delivery systems, and to improvements in engine control strategy. These engine modifications resulted in reduced catalyst light-off times and improved AFR control. Emissions improvements, over the modified European test cycle, as a result of these changes were approximately 50% for CO and NOx and 30% for THC. A fuel matrix was designed in order to study the effect of six fuel parameters on exhaust emissions from the two levels of vehicle technology.

The effects of aromatics and mid-range volatility (E100) were investigated in a fleet of sixteen prototype European gasoline vehicles calibrated to meet the 1996 European emissions limits. A 3x3 fuel matrix was blended with independently varying aromatics and E100, other fuel properties being held constant. The test fleet was chosen with a wide variation in emissions, and vehicles fitted with close-coupled catalysts gave lowest emissions. There was also a wide variation in vehicle response to fuel properties. High HC emissions on some vehicles for fuels with low E100 (35% v/v) were attributed to driveability problems caused by these fuels. Reducing aromatics reduced composite cycle fleet average emissions of Carbon Monoxide (CO), Total Hydrocarbons (THC) and Carbon Dioxide (CO2) but increased Oxides of Nitrogen (NOx). Increasing volatility reduced HC emissions, increased NOx, had no effect on Carbon Dioxide and showed minimum CO at 50% v/v aromatics.

In an effort to reduce CO2 emissions, governments are increasingly mandating the use of various levels of biofuels. While this is strongly supported in principle within the energy and transportation industries, the impact of these mandates on the transport stock’s CO2 emissions and overall operating efficiency has yet to be fully explored. This paper provides information on studies to assess biodiesel influences and effects on engine performance, driveability, emissions and fuel consumption on state-of-the-art Euro IV compliant Toyota Avensis D4-D vehicles with DPNR aftertreatment systems. Two fuel matrices (Phases 1 & 2) were designed to look at the impact of fuel composition on vehicle operation using a wide range of critical parameters such as cetane number, density, distillation and biofuel (FAME) level and type, which can be found within the current global range of Diesel fuel qualities.