Absolutly great ! It is very nice to get something ironed out due to the
whole bevy of people out there who know good stuff. I am now a Thermal
Afterburn guru !!!!
At 03:19 PM 10/18/2003 -0400, Kai M. Radicke wrote:
> > This subject needs expert analysis. I just cannot believe that the air
> > pump results in an after burn as this would mean very hot exhaust
> > pipes and presumably a noticeable belching out of flames.
>
>Barrie, it does, the process is called Thermal Afterburning and I'll just
>now quote right from the Bosch Auto Handbook (pg 521):
>
><begin quote>
>
>Thermal Afterburning
>
>Before today's catalytic treatment of exhaust emissions became standard,
>initial attempts to reduce emissions utilized thermal afterburning. The
>method employs a specific residence time at high temperatures for burning
>the exhaust-gas components which failed to combust during normal combustion
>in the engine cylinders. In the rich range, the process must be supported
>with supplementary air injection (secondary air) in lean-burn engines, the
>residual oxygen in the exhaust gas supports the afterburning process.
>
>In the past, mechanical pumps driven by belts directly from the engine were
>used for secondary-air injection. Since such air injection is only required
>during the engine's warm-up period, these pumps are switched using
>electro-magnet couplings. Lower-priced blower pumps powered by electric
>motors are quickly superseding the former mechanical versions.
>
>Due to its lack of potential, particularly in maintaining low NOx <me:
>collective oxides of Nitrogen> limits, thermal afterburning alone is
>currently considered to be of little significance. It can be used, however,
>to reduce emissions of HC and CO during the operating phase in which the
>catalytic converter has not yet reaches its operating temperature. Because
>it greatly reduces the time taken for the catalytic converter to reach its
>operating temperature, thermal afterburning with air injection during the
>engine warm-up phase in combination with catalytic aftertreatment will play
>a major role in achieving compliance with more stringent emission limits in
>the future.
>
><end quote>
>
>Quoted from the 5th Edition, last updated in 2000.
>
>Kai
Regards
Barrie
Barrie Robinson
barrier@bconnex.net
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