Impact Of Alternative Fuels On Heavy-Duty Diesel Engine Performance And Emissions

Motivation:
With the implementation of extremely stringent environmental regulations and dwindling petroleum supplies worldwide, there is tremendous interest in the use of Alternative fuels such as Fischer-Tropsch (synthetic) and Biofuel, which are non-petroleum based. The use of these fuels on current engines requires a complete understanding of the impact of fuel composition parameters such as density, cetane number, sulphur and aromatic content on combustion performance, fuel economy and emissions when used in combination with current engine emission reduction technologies such as exhaust gas recirculation (EGR) and variable geometry turbocharging (VGT).

Biodiesel and Fischer-Tropsch diesel fuel are attractive due their low sulphur content which favors lower particulate emissions and increases the life of catalysts. The Army (TARDEC) is particularly interested in using Fischer-Tropsch synthetic fuel, since it contains no sulfur and low aromatics and hence has the potential of being a "reformable" fuel to be used in fuel cells. It also has the benefit of having both lower NOx and PM emissions and can come from natural resources within the US, reducing the US dependence on foreign oil.

Goals of the work:

Effect of Biodiesel, Fischer-Tropsch and Ultra low sulphur diesel on engine performance and emissions, particularly NOx and PM. Impact of EGR, VGT and fuel injection timing on exhaust emissions and guidelines for strategies tailored for alternative fuels.

Impact of fuel composition and EGR on carbon soot in PM.

Impact Of Alternative Fuels On Medium- and Heavy-Duty Diesel Engine Performance and Emissions

Researchers:
Dennis Assanis
Zoran Filipi
Ashwin Salvi

Sponsor:
Automotive Research Center (US Army TACOM)

Methodology:
The Navistar V8 6L diesel engine will be operated at various operating conditions to study the effect of EGR with VGT and fuel injection timing on diesel engine characteristics like combustion, pollutant formation, visual signature and performance. The engine operating conditions would be repeated with EGR and different fuel injection timings for Fischer-Tropsch, Biodiesel and Ultra low sulphur diesel fuels. The effects on engine performance and emissions would be established by analyzing pressure and heat release curves for ignition delay and rate of combustion. Of particular interest would be the impact on NOx, PM and fuel economy.

Another aspect that would be looked into is PM composition involving a study of the relative contribution of carbon soot and hydrocarbons in diesel PM. This would be accomplished by a simple chemical analysis of the sample filters obtained from a recently commissioned mini dilution tunnel using Soxhlet extraction method. There is scope for studying the PM composition further by analyzing the extracted hydrocarbons and PAHs in a Gas Chromatograph or Mass Spectrometer.