NOx emission from a spark ignition engine using 30% iso-butanol-gasoline blend:: Part 2 -: Ignition timing

The effect of varying ignition timing on NOx emission, exhaust temperature, knock occurrence and thermal efficiency in a spark ignition engine has been experimentally investigated. A Hydra single-cylinder, spark-ignition, fuel-injection engine was used with a 30% Iso-butanol-gasoline blend as fuel. The ignition timing was varied, NOx emission and knocking phenomena were studied at different fuel-air equivalence ratios. Results show that retarding ignition timing causes the exhaust temperature to increase. For a lean mixture, advancing ignition timing has a great effect on the increase of the level of NOx, while for a rich mixture advancing ignition timing has a minimal effect. Experimental results show that advancing ignition timing causes the peak of NOx emission to be shifted towards the lean fuel-air equivalence ratio. Preheating inlet air increases the knock intensity and causes the knock to occur at less advanced ignition timing. Retarding ignition timing causes the engine thermal efficiency to decrease. (C) 1998 Elsevier Science Ltd. All rights reserved.