Browse Publications Technical Papers 2004-01-0640
2004-03-08

Air -Fuel Ratio Calculation for a Natural Gas Fuelled Spark Ignition Engine 2004-01-0640

Air-fuel ratio (AFR) is a crucial parameter for combustion controls in internal combustion engines. An incorrect AFR metering for reciprocating internal combustion engine causes high toxic gases emissions formulation, serious fuel consumption problems and unbearable combustion noise and combustion deterioration. Traditionally, the AFR is obtained by direct measurement of intake air and the fuel either injected into the combustion chamber or pre-mixed at the carburetor. However, the accurate AFR obtained from direct measurement is difficult due to measuring equipments resolution prone to errors.
This paper describes a method for accurate determination of air-fuel ratio based on exhaust emission gas analysis as an additional tool used to be validated the conventional direct air fuel flow rates measurement. This method explains all the possible parameters that may affect the accuracy of air-fuel ratio measurement which includes the instrument error, ambient conditions, the assumed water-gas shift reaction constant, the humidity of the atmospheric air and the inclusion of nitrogen in the air-fuel ratio model.
Results show that four essential exhaust gas emission concentrations, namely carbon monoxide (CO), carbon dioxide (CO2), oxygen (O2) and unburn hydrocarbons (HCs) are adequate for obtaining an accurate air-fuel ratio. The fuel type and the range of parameters that may affect the accuracy of air-fuel ratio are properly defined. This paper will also present experimental results of a bi-fuel natural gas spark ignition engine to be compared with computational results. The results of this investigation will be used to develop a new dedicated natural gas engine.

SAE MOBILUS

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

Access SAE MOBILUS »

Preview Document Add to Cart
Members save up to 17% 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

Analysis of Combustion Parameters and Their Relation to Operating Variables and Exhaust Emissions in an Upgraded Multivalve Bi-Fuel CNG SI Engine

2004-01-0983

View Details

TECHNICAL PAPER

Effect of Boost Pressure on Engine Performance and Exhaust Emissions in Direct-Injection Compressed Natural Gas (CNG-DI) Spark Ignition Engine.

2009-32-0135

View Details

TECHNICAL PAPER

Experimental Test of a New Compressed Natural Gas Engine with Direct Injection

2009-01-1967

View Details

X