Diesels Aren't Dirty Anymore

Fine dust is also reduced (captured) and as far as I am aware, is fully burnt up in the filter monolith once it reaches proper working temperatures....the filter is basically a petrol catalytic converter without the heavy metals......the ceramic filter should never need cleaning....or replacement.

Almost. The material is usually the same (cordierite or silicon carbide are the most common), but the construction is slightly different. Most catalysts are flow through substrates - all the channels are open at both ends.

Filters, on the other hand tend to be wall flow substrates, with alternate channels blocked at one end and the others blocked at the opposite end, forcing the gas to pass through the material of the wall, leaving the soot trapped in the inlet channels.

sorry about quality, couldn't get the other one to load.

The soot needs a minimum temperature, higher than normal exhaust gas temperatures, to burn off. This reaction temperature can be lowered by catalyst action, whether a separate upstream catalyst or a catalyst coating on the filter. The reaction temperature can be reached, periodically, by running the engine rich, having post injection pulses or injecting fuel directly into the exhaust and igniting it.

Whether or not a filter needs cleaning depends on how the vehicle is used. If it gets a decent (10+ miles at say 40 -50 mph) run regularly, then it will regenerate. If it's only ever used to drive through town on short trips to go to the shop, then it is likely to become blocked. It's the difference between a long distance truck and a refuse vehicle; the CRT® will work well on the former, but not on the latter.

This is also part of the reason the MOT tester advises a decent run before the smoke test. The run burns up some/most of the soot deposited in the exhaust system, ensuring that it doesn't become dislodged during the test and give a false high. It's not quite the cheat that PlbMak thinks it is! It also ensures the engine's warm and less prone to damage from a free acceleration (but you two knew that anyway).

As to the fine particles, there's a bit of an odd phenomenon there. Contrary to popular belief, not all particles are equal, and not all particles are carbon. A very large number of particles are liquid condensates. They become liquid as the gases cool on leaving the tailpipe. Lots of work has been done on their dispersal characteristics.

In an untreated exhaust these would precipitate onto the surfaces of solid matter, making them bigger and sticky. In a treated exhaust, without the precipitation sites, they tend to nucleate of their own accord, forming a very large number or very very small particles. So the tailpipe gases from a filtered system actually contain more nano-particles that an untreated one, but 90+% less mass, and very little elemental carbon. These nano-particles get much further down into the lungs than the black smoky stuff you used to see (roughly, if you can see it, it can't get inside you); they have also been shown to pass through the blood/brain barrier.

Legislation will be changing for a total mass measurement to a particle count, in order to a) get a handle on the current situation and then b) do something about it. After all, you can't control what you can't measure and we are only just developing the technology top measure these things.

They run on the ultra-low-sulfur diesel fuel that became available in the United States in October of 2006.

Congratulation US, catching up with the Old World at last. Europe has been running on sub-50 ppm sulphur diesel fuel since the late 90s, and on sub-10 ppm for the last couple of years (Sweden are world leaders and are running on 0-2 ppm stuff, they've always been ahead of the pack). It's several years now since European sales of diesel cars exceeded those of petrol (gasoline) cars.

Here are the US EPA site's comments - US stepping from 500 ppm to 15 ppm.

The reason this is important (apart from the removal od SOx from the atmosphere) is that sub-50 ppm fuels allow the use of precious metals catalysts in the exhaust. Sulphur poisons the catalysts. Oxidation catalysts remove most of the unburnt hydrocarbons and oxidise CO to CO2 - which has health benefits, if not greenhouse benefits (far more difficult to gas yourself on a catalysed exhaust stream) and reduce particulate mass by about 10 - 15% , by oxidising the carbon to CO2 and oxidising some of the volatile condensates.

The big reduction in particulate mass comes from the use of filters and the best designs need no outside intervention. I don't know details of PasCar systems; I believe most of these use back pressure feedback to run the engine rich, briefly, or initiate a post-ignition fuel pulse in order that the exhaust gases ignite after leaving the cylinder, to raise the temperature of the exhaust stream and thus force a regeneration (burning off of collected soot) of the filter. The systems vary between manufacturer. I don't know of any retrofit systems available for PasCar (i.e. systems not designed by the manufacturer).

What I do know about are commercial vehicle exhausts. Here a different system is often used, where a combination of an oxicat and a filter are used. The cat changes the composition of the exhaust gases in such a way that the reaction temperature of the soot is lowered into the normal exhaust gas temperature range and so it is burnt off continuously, resulting in a more or less constant back pressure trace. These systems have been proven to remove 99% of particulate matter by mass.

Other bits of the article:

The E320 BLUETEC boasts 40 percent better fuel mileage than a comparable gasoline-powered model, and its EPA city/highway rating of 27/37 mpg means it can cruise more than 700 miles on a single tank of fuel, said Patrik Borenius, manager of advanced product planning for Mercedes.

No-one in Europe would touch a brand new car with such a high fuel consumption. My six year old Skoda Octavia does over 52 - 54 mpg on mixed driving (drops off to about 48 on long journeys at 85 mph!). Most of us couldn't afford to run a 37 mpg car.

"And right now, with all the concern about the environment, and fuel prices up over $3 a gallon again, and oil at around $100 a barrel, we are clearly hearing from our customers that they want something cleaner and more fuel-efficient."

I'd love to pay $3 a gallon. Currently we're paying £1.06 per litre - that's $9.56 a gallon. I can't remember when we paid $3/gal (33p/litre), about 1990 I think.

"But today's clean-diesel engines are as clean as gasoline-powered engines," says Chrysler's Altermatt. "The standards have really improved, and that's partly due to the input from the government, in terms of implementing stricter emissions standards. But we've developed diesels in a responsible manner."

They have to be as clean, by law. ALL vehicles have to meet the emissions legislation - the only differences are based on vehicle weight, not engine type (unless it's gas (LPG) powered!).

For the commercials, the following regs apply:

We're currently inside the red box, next year we have to get to the green box. As you can see, since 1996, the Particulate Mass emitted by HGVs has reduced by 92%; NOx levels are currently half of what they were. As is the case with most engineering "opportunities for improvement", the reduction of NOx from an engine is usually accompanied by an increase in PM and vice versa. A lot of research and technology has gone into developing engines and engine+aftertreatment arrangements which can reduce both of these simultaneously.

"And in addition to now meeting those higher standards, these engines often provide the customer with engine performance that is the equivalent of gas engines, and sometimes better. And in many cases, the vehicles powered by diesel engines are more fun to drive, because they have better low-end response."

Oh yes. Much more fun. I had a 1994 Peugeot 405 1.9 litre TDI diesel estate. It was so much fun leaving boy racers standing at lights - not only outgunned by a diesel, but by a woman driver. Sweet.

When Volvo decided to enter the World Touring Car Championships (1996 I think), they did so with their large (740 size) diesel estates, they stormed the entire series. So much so that the rules were changed so that this style of car was outlawed; the petrol boys didn't like it at all! I heard that the biggest problem the drivers had was adjusting to the lower engine note (diesels top out about 5-6000 rpm where a petrol would be 12 -15000rpm). Apparently, when first test driving the Volvos, they punted a number into the scenery because they didn't realise they were still doing 100+ mph coming into a corner. They had to recalibrate their ear-foot co-ordination!

Annual emission reductions will be equivalent to removing the pollution from more than 90 percent of today's trucks and buses, when the current heavy-duty vehicle fleet has been completely replaced in 2030, says the organization.

Which is where the retrofitters come in. The European LEZs (Low Emissions Zones) require that all vehicles, of whatever age, meet a certain emissions standard. This is usually less stringent than that required for new vehicles, starting at Euro III minimum and phasing up to Euro IV over a few years. There are a number of companies offering exhaust aftertreatments that can take a Euro II or Euro III vehicle and reduce its emissions to Euro IV or even, in the case of SCRT(R), to Euro V levels. The LEZs either offer incentives to fit the systems or reduce road tax/entry tax to vehicles that meet the limits. So the fleet emissions will be reduced far more quickly that the fleet turnover rate.

In April, the E320 BLUETEC was named the "2007 World Green Car" at the 2007 New York International Auto Show.
Is that "International" as in "World Series"?

The Large Vehicles regulations have always lagged behind the PasCar regulations, but that gap is now closing. The Off-Road (Construction & Agricultural) Sector is still some way behind, but plans are in place to bring these up to the On-road standard in the next 5 or so years. It will be a quicker pace than for the on-roads because much of the technology exists, and is in series production, thus making it more economic for the smaller quantities in this sector. There is still some work to be done, however, to be able to use these technologies is the very different operating conditions found off-road.