Abstract
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 the producer gas on the combustion process and the engine-out emissions. The in-cylinder HC concentration at the vicinity of the spark plug and the UHC concentration in the exhaust port near the exhaust valve was measured using FFID. The experiments showed that addition of producer gas had reducing effect on the UHC emission at conditions leaner than λ=1.40. 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.
