Background

As renewable fuel mandates are enacted in North America and as fuel economy standards become more demanding, there is a need to better understand the synergies between the proposed fuels that meet cleaner domestic renewable energy production goals and the technologies that allow better fuel economy to ensure that the interactions between these solutions do not produce undesirable effects. As an example, the use of ethanol in gasoline has increased dramatically in a number of countries, such as in the United States, where ethanol use has expanded six-fold since the year 2000. Market growth is expected to continue for at least the next decade.

Globally, vehicle manufacturers are pursuing a number of ways to improve engine efficiency. Two notable strategies include downsizing engines and using direct injection (DI) with turbocharged spark ignition (SI) engines. Emissions of particulate matter (PM) are not currently a problem in gasoline engines, but PM emissions regulations are becoming more stringent. Plus, the particle number concentrations in DISI engines have been shown to be greater than that for port fuel-injected gasoline engines and greater than that for compression-ignition engines with diesel particulate filters.

Purpose and Objectives

Because of such factors as the increasing use of ethanol, the growing number of DISI engines available from vehicle manufacturers, and the impact on the design and effectiveness of aftertreatment systems, there is a need to understand particulate formation resulting from the interactions of ethanol-gasoline blends in DISI engines. Initial research has shown that low-level ethanol blends reduce PM formation; however, further confirmation is needed. Particulate formation is basically unknown in the cases of butanol blends. This subtask to Annex XXXV is designed to shed light on these issues.

Project Scope

The project involves comparing direct injection of ethanol-blended fuels to direct injection of gasoline-injected fuels. It is proposed to perform steady-state engine dynamometer tests with a common gasoline DI engine and compare emissions, power, and fuel economy. It is suspected that ethanol may have a larger advantage for brake-specific power because of the high octane of the fuel and increased in-cylinder cooling of the intake air charge.

Studying transient operation and simulated drive cycles is not considered practical for the scope of this project because of the complexity and effort involved in engine calibration. Total hydrocarbons will be measured via a flame ionization detection method in lieu of speciated hydrocarbon measurements to limit the overall program cost. Dual-fuel operation with split injection is not considered part of the scope of the project. An optional, but desired, component would be to use the same engine converted to port fuel injection to perform the same tests.

Activities to Date

The U.S. portion of the project builds on an existing project at Argonne National Laboratory (Argonne) using a General Motors 2.2-liter, inline 4-cylinder, 16-valve DISI engine and involving the following test matrix:

• Engine conditions

– Idling speed

– 2,000 rotations per minute (rpm) and three different engine loads (25%, 50%, 75%)

• Fuels

– Baseline certification fuel

– E10

– E85

– BU16

• Particulate measurement

– Size and number

– Morphology: Primary and aggregate particle size, Fractal geometry

Particulate matter mass, size distribution, and morphology (aerodynamic diameter, fractal geometry, etc.) are being measured and correlated to engine speed, load, and fuel.

Continuing Activities

The results from the Argonne project will be compared to results from other laboratories.

Environment Canada – Emissions Research and Measurement Section will conduct chassis dynamometer tests on a model year 2011 light-duty vehicle with a 2.4-liter DISI engine meeting Tier 2 Bin 5 North American Emissions standards. Tests will be performed with baseline certification fuel and E10. Transient tests along with steady states will be conducted. The transient emissions results will be used as baseline tests that can be replicated in European test cells with European models. The steady-state tests will be used to compare the differences in gaseous and particulate emission rates between the baseline fuel and E10, with the emission changes noted with the engine tests performed at Argonne.

For calendar year 2012, Environment Canada will investigate the option of emissions testing of a 2.4-liter DISI engine with ethanol blends.

Results

Work on this subtask is just getting under way. Engine test results should become available over the course of this calendar year..