The need for a catalytic converter within the exhaust system of automotive engines in order to meet emission regulations and the associated costs of its design and testing have meant that a computational model is highly desirable. A number of models have been developed with increasing completeness and versatility. Each model has used approximations and simplifications to reduce the computation time and to enable their use as a design tool to be viable. The present project utilises a commercial Computational Fluid Dynamics (CFD) code STAR-CD to model the initial stages of a catalytic converter in a motor vehicle starting from cold. The ultimate aim is to be able to use the model to improve the efficiency of a catalytic converter by reducing the time taken for light-off. A detailed single channel study is utilised to provide the geometric versatility of the model and to assess the feasibility of using a thin film approach (with heat transfer coefficient as a function of distance down the monolith) which can be utilised in a full equivalent continuum model. The results of this unique study show that the heat transfer from the gas to the monolith can be reliably quantified for a given geometry under common input variables. For typical ceramic substrate monoliths the heat transfer towards the rear of the channels was given by a Nusselt number of approximately 3.5 with elevated heat transfer in the developing region near the channel entrance. Sinusoidal metallic substrate monoliths had a fully developed heat transfer of 2.4.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:364484 |
| Date | January 2001 |
| Creators | Day, Edward George Wedgewood |
| Publisher | Coventry University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://curve.coventry.ac.uk/open/items/65450a22-045e-2e1a-b454-d56eb923c39d/1 |
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