Search Results

The use of methanol as an automotive fuel can be expected to become significant in North America during the 1990's. Methanol fuel will be sold as 85%/15% MeOH/gasoline mixture. Limited availability of methanol fuel in some parts of North America will require methanol vehicles to be dynamically adaptable to fuel compositions ranging from 85% methanol to 100% gasoline. One approach to meeting such a requirement is a sensor that is mounted somewhere in the vehicle's fuel handling system that determines the concentration of methanol in the fuel flowing to the engine. The output of the sensor is supplied to the computer controlled engine management system that sets engine operating parameters. A sensor based on near infrared absorbance is the subject of this paper.

A proportional sampler for vehicle feedgas and tailpipe emissions has been developed that extracts a small, constant fraction of the total exhaust flow during rapid transient changes in engine speed. Heated sampling lines are used to extract samples either before or after the catalytic converter. Instantaneous exhaust mass flow is measured by subtracting the CVS dilution air volume from the total CVS volume. This parameter is used to maintain a constant dilution ratio and proportional sample. The exhaust sample is diluted with high-purity air or nitrogen and is delivered into Tedlar sample bags. These transient test cycle weighted feedgas samples can be collected for subsequent analysis of hydrocarbons and oxygenated hydrocarbon species. This “mini-diluter” offers significant advantages over the conventional CVS system. The concentration of the samples are higher than those collected from the current CVS system because the dilution ratio can be optimized depending on the fuel.