PARAMETRIC STUDIES AFFECTING LIGHT OFF TIME OF CATALYTIC CONVERTERS

Automobile Engineering

Control of harmful emissions during cold start of the engine has become a challenging task over the years due to the ever increasing stringent emission norms. Positioning of the catalytic converter closer to the exhaust manifold is an efficient way of achieving rapid light-off temperature. On the other hand, the resulting higher thermal loading under high- load engine operation may substantially cause thermal degradation and accelerate catalyst ageing. The objective of the present work is to reduce the light-off time of the catalyst and at the same time to reduce the thermal degradation and ageing of the catalyst to the minimum possible extent. In the present work two innovative approaches namely Parallel Catalytic Converter (CCP) System and Catalytic Converter in Series at Different Position (CCSP) have been adopted to reduce the light-off time of the catalyst. The tests were conducted on a 4 cylinder Spark Ignition Engine under cold start condition. It was established that considerable reduction in the light-off time was achieved by using CCSP. Further reduction in the light-off time was achieved by using pre catalysts (40%vol). It has been found that 13% reduction in CO light-off time was achieved with pre-catalyst (40%vol.) when compared to CCSP. Also 14% reduction in HC light-off time was achieved with pre-catalyst (40%vol.). It was also established that light-off time of CCSP can be brought down to 10 seconds using hot air injection.

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