Influence of Catalysis on Combustion in Spark Ignition Engine

Problems of ignition and flame development in combustion chambers of internal combustion engines supplied with lean, homogeneous, fuel-air mixture are of fundamental importance. One of the effective methods, which can improve flame initiation, is catalytic assistance of ignition and combustion. To be able to use catalysts efficiently in combustion processes in engines, it is necessary to know in detail their catalytic properties. The microcalorimetric method used before to determine characteristic temperatures of catalytic reactions was able to determine catalytic performance very roughly, because measurements were carried out at constant pressure and temperature of the analyzed mixtures. It was impossible, under such conditions, to evaluate precisely the influence of the catalysts on the progress of the combustion processes inside of the combustion chamber.

In the present work properties of the catalyst are examined in conditions very similar to those in the engine. Experiments with catalytic assistance of ignition and combustion were carried out in a rapid compression machine. The combustion area in the cylinder was divided into two parts: the main combustion chamber and prechamber. A catalyst with a developed surface was placed in the prechamber. The temperature of the catalyst was controlled by means of a special electronic device. A torch ignition from the prechamber created a swirl in the main chamber. The influence of the catalyst temperature on ignition and combustion of a propane-air mixture was extensively examined in special sets of experiments. Pressure records and history of flame propagation registered by a high speed video camera showed some advantages of catalytic the assistance of ignition and combustion.