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An experimental study was performed to investigate diesel particulate filter (DPF) performance during filtration with the use of real-time measurement equipment. Three operating conditions of a single-cylinder 2.3-liter D.I. heavy-duty diesel engine were selected to generate distinct types of diesel particulate matter (PM) in terms of chemical composition, concentration, and size distribution. Four substrates, with a range of geometric and physical parameters, were studied to observe the effect on filtration characteristics. Real-time filtration performance indicators such as pressure drop and filtration efficiency were investigated using real-time PM size distribution and a mass analyzer. Types of filtration efficiency included: mass-based, number-based, and fractional (based on particle diameter). In addition, time integrated measurements were taken with a Rupprecht & Patashnick Tapered Element Oscillating Microbalance (TEOM), Teflon and quartz filters.

Three distinct types of diesel particulate matter (PM) are generated in selected engine operating conditions of a single-cylinder heavy-duty diesel engine. The three types of PM are trapped using typical Cordierite diesel particulate filters (DPF) with different washcoat formulations and a commercial Silicon-Carbide DPF. Two systems, an external electric furnace and an in-situ burner, were used for regeneration. Furnace regeneration experiments allow the collected PM to be classified into two categories depending on oxidation mechanism: PM that is affected by the catalyst and PM that is oxidized by a purely thermal mechanism. The two PM categories prove to contribute differently to pressure drop and transient filtration efficiency during in-situ regeneration.

The natural gas vehicle has high potential as an Environmentally Enhanced Vehicle (EEV). In order to achieve low-emissions, a precise gaseous injection system coupled with optimized feedback control is necessary for the natural gas engines. An advanced natural gas vehicle, such as the Honda Civic GX, can meet the Super-Ultra-Low-Emission Vehicle (SULEV) emission standard in California and also meet the future European & Japanese emission standards. The low-emission natural gas vehicle emits very low off-cycle emissions, air toxic emissions and has zero-fuel evaporative emissions. The use of natural gas-based fuels achieves CO2 emission reductions relative to use of petroleum-based fuels. Low-emission NGVs are attractive for use in urban and metropolitan city centers to reduce smog.

A dedicated compressed natural gas (CNG) vehicle, based on the Civic 1.6 liter gasoline vehicle, has been developed. In order to optimize the engine for natural gas, the compression ratio, valve train system and exhaust system have been modified. Engine durability for operating on natural gas reaches high standards by selecting each engine component for the CNG application. A gaseous injector and integrated 2-stage pressure regulator were developed for precise fuel metering control. Consequently, high performance and exhaust emissions at “1/10th of ULEV” are achieved.

A Flexible Fuel Vehicle (FFV) has been developed to accommodate the use of both gasoline and M85 in the same engine. The methanol content of fuel is detected by a capacitor type alcohol sensor. The power and torque of the engine increase 8% if the M85 is used. One number colder spark plug is sufficient for the FFV engine to tolerate pre-ignition with M85. FFV engine oil shows improved wear characteristics under severe operating conditions. Chrome-plated piston rings should be used for methanol engines. Valve and valve seat wear, durability of fuel injectors have been considerably improved for methanol engines. The exhaust emissions from a FFV can be maintained at a low level. Further reduction of exhaust emissions is possible if the durability of fuel injectors is fully proven. Most aldehyde and methanol emissions are emitted before the catalysts light off. OMHCE emissions are lower and NMOG emissions (before the reactivity adjustment) are higher for a M85-fueled FFV.

Pre-ignition phenomena of methanol fuel (M85) and unleaded premium gasoline were studied with use of the post-ignition technique. The combustion pressure as well as a signal from the pre-ignition detector were analyzed. It was found that methanol fuel is more susceptible to pre-ignition compared to gasoline fuel. Large cycle-by-cycle variations are present with combustion by surface ignition at the time of pre-ignition. This was caused by wide variations in the 0% mass fraction burned point. Since ionization signals from the pre-ignition detector prior to spark ignition indicate the 0% mass fraction burned point by surface ignition, prediction of pre-ignition is possible with use of the post-ignition technique. Platinum tipped spark plugs were found to be highly susceptible to pre-ignition with methanol fuel.