A Simple Physical Model for High Power Enrichment Emissions

Abstract

A model was developed to predict CO emissions from conventional automobiles during high-power operations. This effort is aimed at improving regulatory modeling through the use of parameterized physical modeling, with minimal parameterization. The emissions studied here are associated with command enrichment of the mixture at high power. An approximate mathematical formula for the rates of CO emissions relative to fuel consumption is established as a function of air-fuel ratio. The CO emissions are modeled by combining a fuel consumption model with a description of a vehicle's enrichment behavior. The methodology for the latter is based on steady state measurements of 29 vehicles at the Environmental Protection Agency Laboratory in Ann Arbor, Michigan, and measurement of ten cars on a hard acceleration cycle by the California Air Resources Board. The research intended to find an approximate description of a vehicle's command enrichment with a minimum number of parameters. In particular, a single parameter representing the strength of enrichment was found to give fairly good results.