Effects of triglyceride gasoline blends on combustion and emissions in a common rail direct injection diesel engine

Abstract

This study presents the combustion and emission results using a blend of unrefined triglycerides (straight vegetable oils) and regular unleaded gasoline in a compression ignition engine typically used in farming machinery. Most farm equipment is powered by diesel engines. A sizable cost of producing a crop on a farm can be attributed to fuel—diesel in such cases. Farmers and researchers have been interested in the use of alternative fuels, especially triglycerides, which could potentially bring down the fuel cost portion of the farm input costs. One of the major drawbacks of using unrefined triglycerides is poor cold flow properties due to high density and viscosity. To overcome this, the triglycerides can be blended with gasoline to lower the density and viscosity. This blend has been used in existing diesel engines without the need for any modification to the engine or its control system. The experiments were conducted on a 4.5-L Tier 3 engine. The fuel used was a blend of unrefined canola triglyceride and regular unleaded gasoline (10% by volume). Measurements include mass fraction burned combustion pressure, fuel consumption and pollutant emissions. The fuel consumption of TGB10 was lower than most straight vegetable oils found in the literature, but higher than diesel. The peak pressure of TGB10 was slightly higher than diesel and occurred earlier than diesel. The brake-specific NOx was lower than diesel at lower and no load points. Particulate matter emissions of TGB10 were higher than diesel at rated speed. Total hydrocarbon emissions were generally higher than diesel. CO emissions were lower than diesel except at low or no load points where they were significantly higher.