Show simple item record

dc.contributor.advisorWai K. Cheng.en_US
dc.contributor.authorLang, Kevin R., 1980-en_US
dc.contributor.otherMassachusetts Institute of Technology. Dept. of Mechanical Engineering.en_US
dc.date.accessioned2008-03-26T20:37:16Z
dc.date.available2008-03-26T20:37:16Z
dc.date.copyright2006en_US
dc.date.issued2006en_US
dc.identifier.urihttp://hdl.handle.net/1721.1/36191
dc.descriptionThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.en_US
dc.descriptionIncludes bibliographical references (p. 163-165).en_US
dc.description.abstractAn experimental study was performed to investigate strategies for reducing cold start hydrocarbon (HC) emissions from port fuel injected (PFI) spark ignition (SI) engines with better use of existing hardware and control systems. Engine experiments and computer simulations were used for three major phases of the project: the effect of variable valve timing on first cycle mixture preparation, the interaction between fuel injection and valve events, and the development of a flow reactor exhaust manifold for fast catalyst light-off. For the first cycle of cranking, delaying the intake valve opening (IVO) creates a pressure difference across the valve, resulting in strong but brief shear flow to facilitate atomization; delayed IVO also produces a cooler charge due to the expansion process before IVO. It was observed that the in-cylinder equivalence ratio increased with delayed IVO, primarily by displacing the lean portion of the stratified cylinder charge back into the port. However, HC emissions for the first cranking cycle increased with delayed IVO. With closed valve injection, injection timing has no significant impact on mixture preparation or emissions. With open valve injection, however, HC emissions scale with both valve lift and mass flow because of increased cylinder wall wetting.en_US
dc.description.abstract(cont.) By timing split injection such that the second injection event hits the overlap back flow, a small mixture preparation and emissions benefit was achieved. Earlier IVO results in a longer back flow period, however the impact on mixture preparation is small. The observed reduction in HC emissions resulted from a higher residual gas fraction due to early IVO, which yielded later combustion phasing, which in turn yielded increased post-flame oxidation. Under steady-state cold coolant conditions, operation of a 4-cylinder engine with three cylinders running rich and the fourth used to pump air into the exhaust manifold resulted in near total oxidation of CO and HC at sufficiently retarded spark timing. Exhaust gas temperatures and enthalpy flow rates were significantly higher than for the conventional engine configuration at fast idle. Using this strategy to perform real cold starts proved challenging without the additional hardware needed for sufficient control over air flow to the engine.en_US
dc.description.statementofresponsibilityby Kevin R. Lang.en_US
dc.format.extent172 p.en_US
dc.language.isoengen_US
dc.publisherMassachusetts Institute of Technologyen_US
dc.rightsM.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.en_US
dc.rights.urihttp://dspace.mit.edu/handle/1721.1/7582en_US
dc.subjectMechanical Engineering.en_US
dc.titleReducing cold start hydrocarbon emissions from port fuel injected spark ignition engines with improved management of hardware & controlsen_US
dc.title.alternativeReducing cold start HC emissions from PFI SI engines with improved management of hardware & controlsen_US
dc.typeThesisen_US
dc.description.degreePh.D.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Mechanical Engineeringen_US
dc.identifier.oclc75960407en_US


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record