1972-02-01

Exhaust Hydrocarbon Emissions from Gasoline Engines - Surface Phenomena 720255

A detailed understanding of the surface phenomena associated with exhaust hydrocarbon (HC) emissions is required to be certain that all avenues of emission control, internal to the combustion chamber, have been exploited. This paper presents information obtained on a single-cylinder research engine, which supports the following hypotheses: there exists a critical piston top land-to-bore clearance above which HC emissions decrease sharply; the presence of an oxidatively active catalytic surface in the combustion chamber increases HC emissions; using a clean engine operating on a fuel containing 5% lubricating oil, HC emissions increase within minutes to a level comparable to that obtained with equilibrium deposits; the first parcel of gas to leave the exhaust valve contains an order of magnitude lower concentration of HCs than does the total mixed exhaust; and a cylinder bore tapered outward towards the top eliminates oil-droplet formation in a motored engine.
In order to predict exhaust HC emissions from the top land volume, an equation is derived which accounts for the effects of piston and bore expansion, blowby, and cylinder-pressure ratio. This equation is applied to literature data obtained on the decrease of HC emissions with an increase in engine speed.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Members save up to 18% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:
TECHNICAL PAPER

Combustion Chamber Deposits: Fuel and Lubricant Effects on Exhaust Hydrocarbon Emissions Measured by Fast FID Analyzer

2000-01-2024

View Details

TECHNICAL PAPER

Audit of Fuel Utilisation During the Warm-Up of SI Engines

971656

View Details

TECHNICAL PAPER

High Bandwidth Heat Transfer and Optical Measurements in an Instrumented Spark Ignition Internal Combustion Engine

2002-01-0747

View Details

X