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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.

The accuracy of low-level emission measurements has become increasingly important, due to the development and implementation of SULEV and PZEV vehicles. One technique to test the low-level measurement performance of a CVS is to inject a known mass of a trace gas, such as propane, into the sample system and verify that substantially all of the mass injected is recovered, typically within 2% of the total injected mass. A Vehicle Exhaust Emission Simulator has been used to inject precise amounts of trace gases with a known accuracy in the range of 0.5% to 1.0%. Recoveries for propane, carbon monoxide, and carbon dioxide are typically 98% or higher, while recoveries for nitrogen oxide are sometimes as low as 95% to 96%. In other words, as much as 5% of the injected nitrogen oxide mass is not recovered by the CVS. This represents an unexpected loss of 3% to 4% of the injected nitrogen oxide.

The application of Selective Catalytic Reduction (SCR) to control nitric oxides (NOx) in diesel engines (2010, Tier 2, Bin5) introduced significant amounts of Ammonia (NH3) and Urea to the NOx exhaust gas analyzers and sampling systems. Under some test conditions, reactions in the sampling system precipitate a white powder, which can accumulate to block sample lines, rendering the exhaust emission sampling inoperable. NOx gas analyzers used for exhaust measurement are also susceptible to precipitation within the sample path and detector components. The contamination requires immediate maintenance for powder removal to restore baseline performance. The results of experiments to eliminate the powder are presented. Analysis of the powder identifies it as ammonium nitrate (NH4NO3) and ammonium sulfate ((NH4)2SO4), which is consistent with the white crystalline precipitate.

Diesel fuel may be blended with ethanol as a bio-fuel extender. However, ethanol is not miscible with diesel fuel, so an emulsifier must be added to a diesel-ethanol blend to prevent the ethanol fraction from separating in a fuel tank. This diesel-ethanol blending and storage problem can be avoided by installing a separate ethanol fuel tank, fuel pump, and ethanol fuel injector that operate in parallel with the standard diesel fuel injection system. A Medium Duty diesel truck has been modified for blending ethanol with the standard diesel fuel consumed by the engine. The ethanol is injected into the intake air so that diesel and ethanol aerosols are blended in the engine cylinder. The ethanol injection is synchronized with the diesel fuel injection, where the proportion of ethanol to diesel fuel is constant. Vehicle tests include EPA FTP procedures on a chassis test cell dynamometer.

A 2.5-liter light-duty diesel van certified to Euro 4 emission standards was tested in a chassis dynamometer test cell, which included a modal FTIR exhaust gas analyzer with the capability of measuring 22 separate gas species. The engine was equipped with a cooled Exhaust Gas Recirculation (EGR) system, which controls the nitrogen oxide emissions (NOx) to less than the 390 mg/km limit required by Euro 4 regulations. The vehicle was tested by dynamometer with the New European Drive Cycle (NEDC) sequence, and found to exceed the 390 mg/km NOx limit. The FTIR was applied as a diagnostic tool for the engine EGR function. The FTIR monitored N₂O, NO, NO₂, and NH₃ over the NEDC test cycles. The linear-control EGR valve failed abruptly during a subsequent test, and the relative concentration of the reduced and oxidized nitrogen species showed significant changes.

A test cell was developed for evaluating a 6-speed automatic transmission. The target vehicle had an internal combustion 5.4L gasoline V8 engine. An electric dynamometer was used to closely simulate the engine characteristics. This included generating mean torque from the ECU engine map, with a transient capability of 10,000 rpm/second. Engine inertia was simulated with a transient capability of 20,000 rpm/second, and torque pulsation was simulated individually for each piston, with a transient capability of 50,000 rpm/second. Quantitative results are presented for the correlation between the engine driven and the dynamometer driven transmission performance over more than 60 test cycles. Concerns about using the virtual engine in validation testing are discussed, and related to the high frequency transient performance required from the electric dynamometer. Qualitative differences between the fueled engine and electric driven testing are presented.