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To give an example: Twin-dosing of urea reduces NOx by approximately 80% on passenger cars.
@The Lurking Jerk & Michael Some parts of this concept are already in production on passenger cars. I suppose this answers most of your questions/concerns.
Then, the efficiency should be higher than 45% since this can be achieved in a rather conventional diesel engine running on ethanol. Moreover, a practical hydrogen fuel cell seems to be limited to about 60%. This should also be compared to a level of up to 55%, which seems feasible with an advanced diesel cycle and compound turbine in a not so distant future. Options, or extensions to turbo compounding, could be a rankine bottoming cycle, dissociation of ethanol, or a more advanced combustion cycle (e.g. something like HCCI). A fuel cell has "cool" exhaust and no option for recovering waste energy. It is not as if a fuel cell, per definition, would be superior. Moreover, it is not easy to aim at a moving target. Nevertheless, the use of alcohol fuels in fuel cells would overcome the problems in the distribution and storage of hydrogen. This is, more or less, a show-stopper today.
@SJC_1 Yeah, but only if efficiency is high (preferably approaching 96%); not around 30%. I see no information about efficiency (?). The case for the direct methanol fuel cell is similar. Interesting, but not feasible at current efficiency levels.
All right, here we have better info: https://www.motortrend.com/news/duramax-ddsf-cylinder-deactivation-chevy-silverado-gmc-sierra/
I found this quote after a quick search: "There are many similarities,” Bailey said. “Whether it’s a gasoline, spark-ignited engine or compression-ignited engine, you have to modify the valvetrain. So we need the capability to deactivate cylinders on an individual basis." https://www.freightwaves.com/news/cummins-testing-cylinder-skipping-to-reduce-nox-emissions
@sd I am almost 100% sure that they must control the valves. Otherwise, a significant increase in exhaust temperature (and FC reduction) would not be possible. Perhaps someone who has looked at the paper could comment. If it would have been so easy as just to modulate injection, we would have seen this long ago. This technology should have a bigger potential on LD engines.
Gasoline vs. diesel (with similar transmissions): Power: 150 PS vs. 150 PS FC: 4.7 – 4.9 l/100 km for gasoline and 3.6-3.9 for diesel CO2: 117-132 g/km for gasoline and 96-101 g/km for diesel Now we can see why most focus in engine development is on gasoline today. There is some homework to do in this field...
It is nice to see that suppliers have taken on this challenge but I would say "too little and too late" to have any significant impact.
The e-cat has been around for quite some time but has only been in limited production in some case over the years. Perhaps this could lead to a breakthrough.
You can only sell a limited number of cars to "green addicts". https://insideevs.com/news/402234/carlos-tavares-selling-evs-to-green-addicts/
I think there are two main take-home messages from this study: 1) There are many other sources of particle emissions than the tailpipes and 2) This field should be studied in much more detail before conclusions are made. For sure, we already knew about that there were such gaps in the knowledge.
Volvo says 7 g/km in WLTP. This is far less than 7%. If baseline is 200 g/km (?), it would be only 3.5%. Then they also say: “…up to 15% fuel savings” but that is most likely under ideal conditions and it would be far lower under “normal” real-world driving conditions. Still, if the general powertrain development gives approximately 0,5% per year in improvement, it would still be a substantial gain. @Alain Car manufacturers will make a fortune on customers like you. Early adopters always pay a lot for their curiosity.
I just saw a note that Toyota has stopped selling new Prius cars in Sweden. Not any interested customers, as it seems.
@Brian I would say that a 3-liter engine actually provides too much power for this kind of vehicle. Moreover, state-of-the-art for a new twin-turbo 2-liter engine is around 250 hp and with some additional electrical power, you could come pretty close to the performance of a 6-cylinder engine. Regarding NOx emissions, I would guess that this concept should be able to get >90% reduction of NOx in comparison to the Euro 6d (final) RDE limit. Actually, some BMW cars have already showed even lower levels in on-road emissions tests.
When you talk about piston engines and aircraft, consider this concept: A combination of a diesel engine, as the Napier Nomad concept but more up-to-date, and further development of the propfan could work. It would be more fuel-efficient than current jet engines and offset the higher engine weight by the carrying less fuel. However, problems such as, e.g., noise and the relatively low cost of jet fuel today are probably prohibitive. The point is that a piston engine propelled aircraft could perhaps be brought up to modern standards, without too much sacrifice of speed and altitude in the flight. Problems might lie in lack of know-how by jet engine manufacturers for both mentioned technologies and the willingness to allocate resources for such a project. Recall that Junkers Jumo 205-208 was an aircraft diesel engine superior in many aspects to aircraft gasoline engines during WWII. Similar concepts have been proposed in recent time, but instead, I would like to highlight the advancements of Achates, as an example for technology based on a similar concept. Germany lost WWI and much know-how was lost, jet engines came along, cheap jet fuel was available, and Napier did not have the resources to develop their concept further. https://en.wikipedia.org/wiki/Napier_Nomad https://en.wikipedia.org/wiki/Propfan http://achatespower.com/
Better wording. might be to just say that LNG is negative for the climate. There is generally too much focus on tailpipe emissions (or perhaps we should say “stack” emissions in this case…). Methane slip is an issue for all use of methane.
Yes, mahonj, I agree. Tragic. I hinted about this many years ago. GDI should only be allowed in combination with GPF, or, in legislative terms, similar tough emission limits for PN should have been applied for gasoline cars, as for diesel cars, long ago. In the EU, we now have such regulations. In theory, you could meet the PN limits without GPF, for example, by using double injection (GDI+MPI). However, the margins are small and high emissions will be seen in off-cycle and on-road testing under real driving conditions. It appears that most manufacturers will adopt GPF for the EU market. The Prius engine does not use GDI. However, MPI engines also have their own problems, e.g. with cold start at low ambient temperatures or at full load. The only realistic solution to obtain a “clean” MPI under all driving conditions would be to use GPF here as well. Sadly, our legislators have left a loophole here. Recall that the US EPA does not have a PN limit and will not apply such limits in the foreseeable future.
EU has adopted WLTP test procedure, but the USA will of course not do that but rather stick to the FTP-75 procedure that originates from 1975. Protectionism!
Well, many engines have had air swirl in the cylinder long before I was born. In fact, the trend has actually been to reduce swirl for many reasons. After a short glance, I cannot really comprehend how this invention could be used to improve engines, i.e. without introducing such serious drawbacks in other fields so that the net gain would become negligible.
Thanks, Mahonj! Just speculation this time, I have not read the paper...