Conversion to a safer life
"IT IS an intricate, frontline area of research in engineering", says H B Mathur, professor of mechanical engineering at the Indian Institute of Technology, Delhi. A combination of catalyst, catalyst support and metallic casing forms the catalytic convertor.
The convertor developed by NERRI, Nagpur, is attached near the exhaust manifold of the internal combustion engine. The catalyst is coated on monolithic ceramic supports. The convertor includes a plenum disc (a perforated disc between the exhaust and the converter that allows air ventilation) and is insulated by a ceramic blanket to prevent heat loss. The disc has "through channels" which allow uniform flow of exhaust through the reactor.
The exhaust travels through the honeycomb channels, comes into contact with the catalyst (in this case, base metal catalysts), oxidising carbon monoxide (co) and hydrocarbons, and converting them into carbon dioxide and water vapour. While ordinarily co is converted to carbon dioxide at temperatures above 700oC, using the catalyst brings down the required temperature to as little as 300oC. But as the free flow of exhaust is obstructed, engine power can be adversely affected, says Mathur.
A computerised programme based on engine size, fuel type, and the composition of the catalyst has to be prepared for "optimum conversion efficiency", he adds. Besides, optimum convertor utility also depends on external factors such as proper maintenance of the vehicle, running it at stipulated speeds and using good quality fuel.