Emission characteristics of natural gas as an automotive fuel.
Nat Comb Fuels & Lubricants Powerplant & Truck Mtgs St Louis Missouri, SAE Paper 710833, 1971 Oct; :1-7
A study of natural gas as a low-pollution automotive fuel was conducted using a single-cylinder engine, a multicylinder engine, and six vehicles. Results showed that the light-load, lean-limit misfire region of natural gas begins at an air-fuel ratio between 140-150 percent of stoichiometric. Changes in ignition timing significantly influences emissions of nitrogen oxides and hydrocarbons but had little effect on carbon monoxide emission. Lower emissions can be achieved (by adjustment) with current design engines, but with heavy penalty to engine performance. Emissions from vehicles fueled with natural gas are virtually unaffected by temperature change within the range 20 deg - 100 deg f. Natural gas exhaust is estimated to be 22-25 percent as reactive as gasoline exhaust.
Nat. Comb. Fuels & Lubricants, Powerplant & Truck Mtgs., St. Louis, MO, SAE Paper 710833