I'm curious as to why we haven't seen more EGR cooling since it seems to be relatively mature based on use in diesel engines and naively, I don't think it would be as expensive or complex as the different systems designed to deal w/ higher engine out NOx in lean burn engines.

Rafael, you said:

"As with any lean burn concept, the real issue is emissions. If you lean down by using more fresh air, you have surplus oxygen in the exhaust gas so you have to use an expensive NOx aftertreatment system."

the article states:

"Very low to almost zero NOx under lean burn at AFR’s beyond 35:1"

so doesn't that imply they have addressed this problem?

"I'm curious as to why we haven't seen more EGR cooling since it seems to be relatively mature based on use in diesel engines and naively, I don't think it would be as expensive or complex as the different systems designed to deal w/ higher engine out NOx in lean burn engines."

yesplease,

Cooled EGR cannot be used in stoichiometric combustion at below certain charge density (load level) because it will inhibit flame propagation leading to roughness and engine flameout. Ergo, we see cooled EGR mostly on diesel engine at above certain load level. At low load, there is no need for EGR in diesel, as the combustion temp is already way cool.

Ah ha, what if in a gasoline SI engine, you this MUSIC scheme for part-load low enough to keep peak combustion temp cool enough to prevent any significant NOx formation above regulated limit, and bypass the 3-way catalytic converter altogether.
AND at higher load, run the engine at stoichiometric with a maximum amount of cooled EGR that would still support smooth running, while route the exhaust thru the conventional 3-way cat to avoid expensive NOx post combustion treatment?

A little bit more plumbing, but can save a lot of expenses on post combustion NOx treatment, and gasoline engine is still cheaper than diesel, even with DI.

It appears this technology would have the same trade-offs as gasoline HCCI. Certainly, the higher efficiency is welcome, but it still uses a very volatile fuel - gasoline.

In my opinion (I've worked in the air quality field for nearly 25 years, mostly as an air pollution meteorologist/air quality forecaster), lower NOx emissions at the expense of higher VOC emissions is NOT a good thing. We need to continue to reduce anthropogenic VOC emissions to as great of a degree as possible if the goal is truly cleaner ambient air.

This is why I tend to favor diesel engines, at least in the ICE realm, since they can use fuels that are virtually non-volatile, and are arguably the best platform for biofuels.

@Rafael.
It seems to be that you are an insider in European auto-industry. Maybe you could give me an answer to a question I just have got reading in different papers presented at engine-expo.com
Could it be that Hybrid technology in Europe is not promeoted due to strategical reasons (e.g. support of agricluture) but also due to the absecne of European exelence in electrical engineering?
It seems to be that in promoting Diesel, "old-technology" orientated companies are able to work as ever. Old structures, old habitus survies. Motto: "Bizzness" as usual?
If Europe would promote Hybridisation, the European "Grosswirtschaftsraum" would not benefit as much as he does under the current conditions. With Hybridisation Asian battery and electrical companies would benefit but no Franco-German company.
What do you think?

I like your report on the said topic. it is very much impressive

@ yesplease - not sure what you are driving at.

@ Gary Davies - the NOx production rate near the spark plug is as high as ever, but the concentration is diluted by the high AFR during the power stroke. Unfortunately, such extreme AFRs are only feasible at very lower power, e.g. when idling. At elevated power levels, AFRs need to be much lower. You then have to either deal with excess oxygen plus NOx aftertreatment, a complex EGR system or, throttling of the intake.

@ Mark - as I understand it, the spiral merely indicates the flow pattern of the gas in a cylindrical chamber with a tangential port.

@ Roger - the Ricardo approach involves mixing the cooled EGR with fresh air prior to compression in a turbocharger and subsequent intercooling. There are therefore multiple degrees of freedom for controlling the final temperature of the fresh charge as it enters the cylinder. This permits fine-tuning of the combustion rate and engine-out temperatures.

Ricardo claim - credibly, IMHO - that their system supports 20-30% EGR across the entire speed band of their engine. In particular, they do not need to enrich the mixture at high load and near rated power in order to protect the turbo and three-way catalyst.

@ michel - an absence of electrical engineering excellence? Bosch, Siemens VDO, Valeo, Hella, Continental etc. are all European companies with large market share in automotive electrical and electronic systems. No, there are IMHO four reasons for the general reluctance regarding hybrids:

(a) the Audi Duo flopped badly in the 1990s

(b) hybrids are no better than diesels in terms of fuel economy or performance. European emissions regs permit affordable diesels and, European car makers have a home advantage in that technology.

(c) Toyota has managed to monopolize hybrid technology in the public's perception. Even Honda is considered merely a distant second. Most others have encountered limited demand for their full hybrid offerings, partly because many are merely variants of existing SUVs rather than out-and-out fuel saver machines. Unlike Toyota, hybrid technology does little to burnish their brand credentials.

(d) Full hybrid systems remain very costly. Since European consumers already face much higher vehicle prices than their counterparts in the US, interest in full hybrids is muted. A few years ago, the German supply chain made a big push to upgrade the on-board gird voltage to 42V, but car makers decided against it due to cost and concerns about reliability.

However, there is currently a lot of momentum towards the widespread application of micro- and very mild hybrids. BMW calls this Efficient Dynamics and is including it in virtually every new model and model refresh. Citroen has offered a start-stop feature for longer but not on every model. Others, notably M-B, Audi, VW and Opel are following suit, mostly because of the EU's looming CO2 regulations. Look for similar features in their model ranges over the coming 12-24 months. The other major European brands won't be far behind. Electric hybrids are coming in Europe, but they will be less ambitious, cheaper and more ubiquitous than the flashy full hybrids favored in the US.

Also, remember that every turbocharged engine - including every one of the ~8.5 million diesel LDVs sold in Europe this year - is technically a hybrid, just not an *electric* hybrid. After all, what is a TC if not a very small singe-stage gas turbine with pneumatic power delivery?

Of all the ICE innovations, this is the most promising and can be applied right away without significant increase in cost.

The combustion chamber is long and helical but does not necessarily be helical. It is mentioned about the advantage of tangential outlet. The injector is sprayed at the start of compression stage, pushing the mixture all the way to the dead end of the chamber where the spark plug is. The mixture is pushed inward by the further motion of the compression cycle. The fuel ratio is varied by varying the the duration of fuel injection.

@ Gary Davies – I’m approaching this from a U.S. perspective. Since all highway diesel vehicles sold in the U.S. since January 2007 (including all large over-the-road trucks) have been equipped with particulate filters (DPF), diesel PM emissions with respect to new vehicles are really no longer an issue, if they ever were.

All speciated ambient PM monitoring data that I’ve seen show that EC (elemental carbon – diesel PM averages about 75% EC) typically makes up only about 10% - 15% of the ambient PM2.5 mass, and there are a lot of sources of EC other than diesel engines (gasoline exhaust PM is about 25% EC by mass, electric generation plants, wildfires, etc.). OC (organic carbon) typically makes up the largest percentage of ambient PM2.5 mass.

Which bring up another issue regarding anthropogenic VOCs – the production of secondary organic aerosols (SOA). VOCs oxidize in the atmosphere to increasingly low vapor pressure products which in turn increasingly partition to the particle phase by homogeneous nucleation (nanoparticles) or condensation on other ambient particles (heterogeneous nucleation - mostly ultrafine PM). These SOA form primarily from gas-phase hydrocarbons with carbon number greater than or equal to six. Since gasoline is largely made up of hydrocarbons with a carbon number greater than or equal to six (I think, someone please correct me if I’m wrong), evaporative gasoline emissions are potentially responsible for significant contribution to the ambient PM2.5 inventory.

SOA yields of 5% - 10% have been estimated for reactive VOCs (ROG) like gasoline, with aromatics on the high end of that scale. According to the USEPA, in 2002 there were over one million tons of evaporative gasoline vapor emissions in the U.S. from the distribution, refueling, and storage of gasoline, meaning that at least 50,000 tons of organic PM2.5 (as SOA) potentially were produced in 2002. For comparison, there were 99,000 tons of direct PM2.5 mass emissions from highway diesel vehicles in 2002 according to the same USEPA report, but that is expected to be reduced to about 10,000 tons/year by 2030 just from emission controls on highway diesel engines currently in place, according to the USEPA, meaning that SOA from gasoline evaporative emissions will potentially be a much larger source of ambient PM2.5 than highway diesel engines by then (and that’s not including the direct PM emissions from gasoline vehicles, which will continue to climb unless particulate filters are required on them too sometime in the future).

Granted, there is a cost penalty associated with these clean diesel engines, but they now have less of an environmental impact than even the latest equivalent versions of gasoline engines based on consideration of all associated emissions (again in my opinion).

"Indirect combustion chambers are less efficient than direct injection due to thermal and pressure loses, more in this case with a refrigerated spiral path.
¿Do the gains from lean burn and unthrottle compensate those loses?.
¿Is it possible to have an scheme of unthrottled GDI?"

The answer to your two questions are stated in the article: "The MUSIC engine has demonstrated part-load efficiency equal to diesel...", or ~20% gain over conventional stoichiometric-combustion engine." Apparently the efficiency loss in the indirect combustion chamber is minor in comparison to the efficiency gain.

@Carl,
Have ye no faith in EPA and CARB? Apparently, they had all your concerns figured out already, IMHO. Annual car inspection involve a test of the gas tank cap for leakage. All cars have system for preventing evaporative gasoline emission into the air. Summer gasoline batch has much less vapor pressure than winter batch. The fuel filling spigot at the gas station has a system for absorbing the evaporative emission resulting from gasoline filling.

@ Carl

My sources in the US new truck industry tell me that the new clean diesel trucks are not selling. It is believed that many fleet operators will rebuild their chassis rather than buy new. 2007 is possibly the worst sales year ever.

@ Michel -

BMW actually avoids using the term hybrid in connection with its Efficient Dynamics package, because so many people have their own pet definition of it. Valeo does call stop-start functionality a micro-hybrid, so I suppose you can play the definitions game until you're blue in the face.

The BMW system does indeed not directly boost engine torque. It does, however, remove parasitic loads from the engine, so a few extra hp make it to where the rubber meets the road. It also recuperates energy during coasting and braking.