Formation mechanisms of combustion chamber deposits

Combustion chamber deposits are found in virtually all internal combustion engines after a few hundred hours of operation. Deposits form on cylinder, piston, and head surfaces that are in contact with fuel-air mixture during the engine cycle. The effects of deposits include increased engine-out NOx emissions, octane requirement increase, and changes in flame speed and thermal efficiency. A framework is developed for examining the physical and chemical processes that contribute to the formation of combustion chamber deposits. First, a hypothesis for the general mechanism of deposit formation is developed from a review of previous work on this issue. The key features of this mechanism are formation of deposit precursor species from fuel and air as the flame quenches at the engine wall, diffusive and convective transport of these species to the wall, and condensation or adsorption at the wall surface. The experimental system and methodology developed in this work are meant to provide insight into the interactions between these processes, and in particular to study the chemical mechanisms that contribute to the formation of deposit precursor species. A cooled low pressure flat flame burner is used to produce steady-state propane-air flames doped with toluene, a known deposit forming species.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2001

Author dc:creator

• O'Brien, Christopher J. (Christopher John)

Advisor dc:contributor.advisor

• Simone Hochgreb.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/17505

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/17505