Relation of Exhaust Gas Composition to Air-Fuel Ratio 360106
THE increasing use of the analyses of the exhaust gas from an operating engine to measure air-fuel ratio has made the exact relation between composition and mixture ratio of some importance. Complete analyses of the exhaust gas are slow and laborious, and a simple relation between air-fuel ratio and one or more constituents easily determined by chemical analysis, or by automatic measurement of some property of the exhaust gas, is to be preferred, provided a suitable relation or calibration is available. The data in the literature are not altogether consistent.
In the work reported in this paper, complete exhaust gas analyses for carbon dioxide, carbon monoxide, hydrogen, methane, and oxygen have been related to directly measured air-fuel ratios for three engines over a range of operating conditions and with varied air-measuring equipment. The data are consistent and they show that the exhaust gas composition is related to measured and also to computed air-fuel ratios with a deviation of about 3 per cent. The rapid determination of one or more constituents in the exhaust gas, or the measurement of some physical property, thus serves to estimate the air-fuel ratio rapidly and accurately. The results of such measurements are accordingly useful in the investigation of a variety of carburetion and fuel problems and in the rapid estimation of volumetric efficiency.