Search Results

The methyl ester of soybean oil, known as biodiesel, is receiving increasing attention as an alternative fuel for diesel engines. Biodiesel is a nontoxic, biodegradable, and renewable fuel with the potential to reduce engine exhaust emissions. However, previous results have shown that biodiesel-fueled engines produce a higher fraction of soluble organic material (SOF) in their exhaust particulate matter than when petroleum-based diesel fuel is used even when the total particulate emissions are lowered. Most researchers have also observed that unburned hydrocarbon (HC) emissions decrease with biodiesel. In this project, the formation of SOF in exhaust particulates under different measurement conditions and the possibility of deposition of HC vapor in the sampling lines of the HFID detector were studied experimentally and theoretically when the diesel engine was fueled with biodiesel.

A computer model has been developed to predict diesel engine particulate emission during transients in speed and torque. The computer model consists of a quasi-steady-state engine combustion model, a dynamic engine model, and a dynamic turbocharger model. The model uses information developed from steady-state tests to predict the transient particulate emissions. The computer model accurately predicts engine airflow rate, turbocharger speed, and instantaneous engine equivalence ratio. The fuel consumption given by the model is within 3% of the experimental measurement over the EPA transient cycle. The brake-specific particulate emission during the transient cycle is also accurately predicted by the model. The predicted particulate emission is within 5% of the averaged experimental data over the EPA transient cycle.

The methyl esters of soybean oil, known as biodiesel, are receiving increasing attention as renewable fuels for diesel engines. Biodiesel has a high cetane number, and offers the potential of emission reduction. The properties of biodiesel vary depending on its composition, and this may affect engine performance and emissions. In this project, biodiesel fuels were prepared from feedstocks with modified compositions including the methyl esters of a low palmitic soybean oil, a partially transesterified soybean oil, a synthetic blend of saturated esters, and a commonly used methyl soyate. These esters were blended with No. 2 diesel fuel in 20% and 50% concentrations. The blended fuels were then tested in a diesel engine to investigate the effect of biodiesel composition on performance, combustion characteristics, and emissions.

A single cylinder TACOM-LABECO open chamber diesel engine with a special research head, which incorporates an American Bosch Electronic Fuel Injection System, was used to study the effects of air swirl, injection pressure and nozzle geometry on exhaust particulates, NOx emissions, ignition delay, heat release and local heat flux measured at two positions on the head. Air swirl was varied from 0.8 to 4.5 swirl ratio by use of a shrouded intake valve. Peak injection pressure was varied from 35-114 MPa. Five different nozzle geometries were tested. All data were taken at a fixed engine operating condition of 2000 rpm and 0.5 equivalence ratio with an inlet pressure of 1.5 atm and nominal inlet temperature of 340°K.