The effect of a homogeneous combustion catalyst on exhaust emissions from a single cylinder diesel engine

This paper reports a series of experimental investigations into the effect of an Fe-based homogeneous combustion catalyst on the emission characteristics from a four-stroke single cylinder diesel engine. The catalyst contained ferrous picrate as the active ingredient in a composite organic solvent mixture which could be homogeneously dissolved into a commercial diesel fuel at ultra low dosage ratios. The engine tests were conducted at four different engine loads and at two steady speeds of 2800 rpm and 3200 rpm, respectively. Engine exhaust emissions of CO, unburnt hydrocarbons (UHCs) and NOx were measured using an AVL gas analyser and the particulate emissions were evaluated in terms of smoke opacity using a Bosch smoke meter. The results showed that, in addition to the benefit of improved fuel efficiency, the homogeneous combustion catalyst significantly reduced the emissions of particulate matter, CO and UHC from diesel engines. Compared with the reference diesel, up to 3.7% reduction in the brake specific fuel consumption was achieved when the diesel fuel was treated with the catalyst. The use of the catalyst also led to significant reductions in the particulate matter, CO and UHC emissions, with the maximum reductions being 39.5%, 21.1% and 13.1%, respectively. The NOx emissions, however, increased slightly, by ca. 6%, which was consistent with the improved combustion performance as reasonably expected.