Six-seater three-wheelers have gained popularity among the commuters especially for their point to point low fares and better frequency compared to Municipal buses. However, pressure is mounting from all the quarters to ban these vehicles or to drive them out of the municipal limits. These vehicles with maximum loading capacity of 550 kg employ diesel engines which emit high soot & particulate matter or 2-stroke petrol engines which emit carbon monoxide as high as 13 g/km and hydrocarbon as high as 8 g/km, alarmingly high above the 1996 emission norms of 6.75 g/km CO and 5.40 g/km HC. Also the noise levels were higher. Considering the above threat, the authors had taken up the challenge to investigate and curb the pollution by employing high durability metallic catalytic converters.
It was obvious that with conversion efficiency required above 60% for a 2-stroke engine which has high chances of misfiring, a heavy exothermic catalytic reaction in the converter could damage not only the substrate but also the thin carbon steel exhaust system. To overcome these problems, experimental investigations were conducted with respect to Air/Fuel intake system, engine conditions, silencer design, silencer material, converter material and converter location including its inlet & outlet cones.
The paper highlights the final configuration, which not only meets the noise & emission norms but also satisfies the converter durability of 6000 kms within permissible performance deterioration. A road endurance trial has been designed to simulate real-life conditions on Indian roads.