Hydrocarbon Emission from Combustion of Mixtures of Natural Gas and Hydrogen Containing Producer Gas in a SI Engine

摘要

Engine experiments have been conducted on a gas-fueled SI engine. The engine was fueled with natural gas and mixtures of natural gas and hydrogen-containing producer gas in order to examine the effect of addition of producer gas on the combustion process and the engine-out emissions. The experiments showed that addition of producer gas decreased the UHC emission at conditions leaner than λ = 1.40. The CO emission was increased by addition of producer gas. This was mainly caused by unburned fuel CO from the producer gas. No effect of producer gas on the NOx emission was detected. Formaldehyde, which is suspected to cause odor problems from natural gas-fired-engine-based power plants, was measured using FTIR. The investigation showed that the formaldehyde emission was decreased significantly by addition of producer gas to natural gas. The in-cylinder HC concentration at the vicinity of the spark plug and the UHC concentration in the exhaust port near the valve was measured using Fast Response FID (FFID). The manifold FFID measurements showed that the reduction in the total engine-out UHC emission by addition of producer gas is mainly caused by a reduction in cyclic variations and only to a minor extent by a general lower UHC level. It was found that the lower cyclic variation in the UHC emission for the mixed fuel was caused by an enhancement of the post oxidation processes.