The Effects of Fuel Volatility and Structure on Hc Emissions From Piston Wetting in Disi Engines

Document Number: 2001-01-1205

Date Published: March 2001

Author(s):
Yiqun Huang - Univ. of Texas at Austin
Ronald D. Matthews - Univ. of Texas at Austin
Janet L. Ellzey - Univ. of Texas at Austin

Abstract:
Piston wetting can be isolated from the other sources of HC emissions from DISI engines by operating the engine predominantly on a gaseous fuel and using an injector probe to impact a small amount of liquid fuel on the piston top. This results in a marked increase in HC emissions. All of our prior tests with the injector probe used California Phase 2 reformulated gasoline as the liquid fuel. In the present study, a variety of pure liquid hydrocarbon fuels are used to examine the influence of fuel volatility and structure. Additionally, the exhaust hydrocarbons are speciated to differentiate between the emissions resulting from the gaseous fuel and those resulting from the liquid fuel. It is shown that the HC emissions correspond to the Leidenfrost effect: fuels with very low boiling points yield high HCs and those with a boiling point near or above the piston temperature produce much lower HCs. As expected, there is a significant effect of fuel structure for fuels that have the same boiling point. For fuels with the same boiling point, the primary effect of structure appears to be its effect on unburned fuel emissions.

Product Status: In Stock

Included in: PT-91

See other papers presented at SAE 2001 World Congress, March 2001, Detroit, MI, USA, Session: Direct Injection SI Engine Technology (Part D&E)

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