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Actually I think he wd be pleased to have stimulated an interesting discussion.
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at the end of the day it was californi.a that started this emmissions nonsense that made manufacturers go down the catalytic route are they not doing the same at the moment?,a lot of long haired hippies that are one of the richest regions in the world that live in a valley drive the biggest guzzlers then complain when they get smog
I am not an LJK knocker but i dont see him as a super guru either,sorry guys.
catalyst =..............(Greek: καταλύτης, catalytēs) is a substance that decreases the activation energy of a chemical reaction (see also catalysis) without itself being changed at the end of the chemical reaction.
or in my days when i did chemistry it speeds up a process.
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NOI, but a lot of what is spouted above is nonsense.
First off, three-way cats (TWCs) are nothing to do with reducing Greenhouse gasses - they are there to reduce three toxic emissions (NOx, HC and CO).
Oxidation techniques are OK for reducing HC and CO, but you are then left with NOx (acid rain, asthma etc etc). EGR reduces combustion temp and therefore NOx, but can only be used under certain operating conditions. The TWC is a good solution in that it promotes an oxidation-reduction reaction and if the mixture can be maintained at stochiometric (via uP contoller directed by the signal from the lambda sensor) then, with appropriate convertor capacity (to smooth mixture fluctuations from the 'bang bang' nature of the controller) you get almost 'perfect' emissions (i.e. H20 and C02) from the tailpipe. Moreover the catalyst has a long life and can fairly easily be recycled. Drivability is also very good.
Years back I worked on a prototype lean-burn system fitted to an Escort. Basically it used the second-derivative of crankshaft speed to determine changes in piston acceleration and hence give a measure of combustion quality. The system would then lean-off till it reached a misfire threshold (say a few %). Unfortunately the drivability of these lean burn systems was very poor and NOx emissions were quite high.
TWC's have been a very successful technology and were undoubtedly the best solution at the time. A modern vehicle has about 1% the emissions of a 35 year old 'uncontrolled' car.
Various other technologies are continuously being worked on (lots of SAE publications) to bring emissions down still further - but current petrol engine emissions are so low that it is difficult to make significant improvement at sensible cost, hence the increased interest in evaporative emissions and self-monitoring of the emission control system (i.e. second EGO after the cat etc).
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i dont see himas a super guru either,sorry guys.
om, this is not a domain where supergurus roam.
a) cars despite their strategic centrality to the world economic 'system' are small beer.
b) supergurus? Dontcha just mistrust'em?
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In the early 90s Rover demonstrated how a non cat lean burn Metro 16v K-Series GTi could be tuned to produce less CO, CO2 and NoX than a cat equipped equivalent car, one of the TV progs, Top Gear IIRC (or perhaps Tomorrows World), took both cars for a run over a fixed route and agreed that the lean burn car was better to drive, more economical and cleaner, the government didn't listen.
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In the early 90s Rover demonstrated how a non cat lean burn Metro 16v K-Series GTi could be tuned to produce less CO, CO2 and NoX than a cat equipped equivalent car, one of the TV progs, Top Gear IIRC (or perhaps Tomorrows World), took both cars for a run over a fixed route and agreed that the lean burn car was better to drive, more economical and cleaner, the government didn't listen.
The K-series was originally designed with the option to operate lean burn and had the facility (in the early head castings) for the required pressure sensors. A lot of money was spent on lean-burn (not just by Rover) and no engine was ever produced which (under properly controlled conditions) could meet the required low emissions spec. "The Government" was therefore wise to ignore the demo on Top Gear.
In the early 1990's Toyota developed a neat 'hybrid learn burn' technology using a wide-range lambda sensor ('UEGO') which gave a fairly linear output from about 12:1 to about 22:1, combined with 'swirl valves' in the inlet passages this enabling lean cruising - this was used in the Carina E.
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and no engine was everproduced which (under properly controlled conditions) could meet the required low emissions spec. "The Government" was therefore wise to ignore the demo on Top Gear.
IIRC the Rover lean burn demo was endorsed by various associations and trade bodies (the likes of MIRA, SMMT and perhaps Cranfield) as being cleaner than catalyst however the required emissions had been written for cat equipped cars and had been written in stone.
The amount of petrol, and therefore carbon (in today's carbon trading terms), that would have been saved if all petrol cars over the last 15 years had been lean burn and not cat is almost incalculable.
Furthermore a catalytic converter has a fairly large carbon footprint at the point of manufacture.
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