The Hindu Business Line : Question & Auto

I read with interest about new generation diesel engine technologies. I would like more clarity about Honda’s much-talked-about new diesel engine technology which, when introduced in its 2009 cars, will be more environment-friendly than similar gasoline engine vehicles. Will Honda’s cars in India be launched with this engine?

Rajinder Chadha

Honda was a late starter in the field of diesel automotive engines for application in passenger cars. European car manufacturers have had to go through with a step-by-step advancement in diesel engine injection and exhaust technologies over the past several decades during which both performance and improving refinement levels have been the core focuses. Now the focus includes not only improving refinement and performance levels but lowering emissions too.

But, despite its delayed entry, Honda has leapfrogged the technology progression that these companies have had to go through by breaking into the big league with an extremely environment friendly new diesel engine technology called i-CTDi that was first unveiled at the Geneva Motor Show of 2003.

The 2.2-litre diesel engine featuring this technology is currently offered in the European Spec Accord and CR-V. But even this lean-burn, low-emission engine is not good enough to meet the US’ stringent emission norms.

The US’ Tier II Bin5 emission norm for diesel passenger cars can be met by diesel engines that use special post-treatment catalytic converters where a special equipment injects liquid ammonia or urea into the exhaust’s chamber just before the end pipe. This leads to the conversion of nitrogen oxides (NOx) into harmless nitrogen.

But, this system, which is currently in use in Honda’s own iCTD-i engine and Mercedes Benz’s BLUETEC engines, has a limitation as far as the US market regulator is concerned. The ammonia tank needs to be refilled at regular intervals and the whole emission technology hinges on the tank having adequate liquid ammonia.

With its new i-DTEC engine and the self-generating catalytic converter, Honda has managed to bypass the requirement for an ammonia tank. In addition to the refinements to the iCTD-i engine’s combustion chamber configuration and fuel injection system with a 2000-bar common rail injection system, the main changes in the new i-DTEC engine revolves around the new catalytic converter system.

The new i-DTEC catalytic converter utilises a two-layer structure — one layer adsorbs NO{-x} from the exhaust gas and converts a portion of it into ammonia, while the other layer adsorbs the resulting ammonia, and uses it later in a reaction that converts the remaining NOx in the exhaust into nitrogen. Ammonia is a highly effective reagent for reducing NOx into nitrogen in an oxygen-rich, lean-burn atmosphere.

This ability to generate and store ammonia within the catalytic converter has enabled Honda to create a compact, lightweight NOx reduction system for diesel engines. The system also features enhanced NOx reduction performance at 200-300ºC, the main temperature range of diesel engines. Further, the car user need not refill an ammonia tank during regular intervals, failing which the emissions target will not be met.

The new i-DTEC engine is likely to be launched by Honda in its 2009 models. This is also a technology platform that the company is hoping will enable it to successfully break into the diesel passenger vehicles market in the US.

There is no roadmap for launching cars with this engine technology in India. However, there is a strong likelihood that Honda will consider cars with this engine for an India launch after they are debuted in the American market.

After all, the Indian market for diesel passenger vehicles in growing dramatically every year. With the prospect of this engine and technology being as emission-friendly, if not better, as gasoline engines, there can be no arguments about its carbon footprint either.

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