Two wheelers, as a means of transportation, are a quandary to India's environment. The frugal use of gasoline on these vehicles provides economical transportation with low CO2 emissions. Unfortunately, the same engines tend to pollute the environment with high levels of unburned hydrocarbons (HC) and carbon monoxide (CO) emissions. To meet India's new environmental legislation, it will require an integration of catalytic elements within the exhaust system along with some engine modifications to achieve the most cost-effective solution.
This paper will outline the current India two wheeler regulatory requirements along with the catalyst conditions and requirements for meeting the standards. Using an array of modeling tools, laboratory, dynamometer and vehicle testing, emission devices are developed for this purpose. When employing emission control devices on the vehicle, there are trade-off between engine tuning for fuel economy or power that must be taken into account when applying the catalytic elements into the exhaust. It will be shown how the examination of vehicle data under transient conditions can aid a catalyst designer to address warm-up and thermal stability characteristics within the catalytic washcoated elements. Also, an investigation of the engine-out chemistry to the catalyst under dynamic conditions provides useful insight into oxygen availability for reaction with the HC and CO pollutants. To help mitigate for oxygen deficiencies within the exhaust, oxygen storage components (OSC) can be employed to minimize the rich transient HC spikes seen during shift or high acceleration conditions. Thus, the employment of a cost effective emission system requires that engine and catalyst engineers work closely together to define the detailed requirements of the system.
The efficacy of an Engelhard catalyst comes from a unique “segregated washcoat design” that permits the coating architecture to be tailored to the specific application [1]. This results in judicious usage of expensive precious metals to meet performance and durability legislative requirements. These coatings applied to traditional ceramic monoliths showed good durability on a 2-stroke application [2].
Having the ability to uniquely anchor catalytic coatings on most metal surfaces provides a level of flexibility to improve system performance while reducing cost. Flex-coating technology proves an adherent catalytic coating on a number of metal surfaces that are normally found in today's existing muffler or exhaust line designs. Examples of different catalyzed articles that can be used alone or in combination for two wheeler applications will be shown.