Gasoline particulate emissions

sledstorm1

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I have been noticing that some of the newer direct injected gas motors have sooty tail pipes. Ford's ecoboost f150 are bad for this and I have also noticed it happening to new Hyundai sonatas. One sonata was so bad the bumper was stained above the exhaust outlets, it remined me of my old 05.5 brm jetta. Are gas vehicle allowed more particulate emissions then diesel's?
 

wxman

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...Are gas vehicle allowed more particulate emissions then diesel's?
No, but the particle emissions from gasoline engines tend to be much smaller than the particle emissions from diesels. PM emissions are currently regulated by mass in NA, and the extremely small particles from gasoline engines have almost no mass.

The particle number emissions from gassers are much higher than the particle number emissions from diesels with DPF, and in some common driving conditions, are as high or higher than diesel engines WITHOUT DPF.

In Europe, diesel cars now must meet a very strict particle number emission limit (6X10^11 particles per km), and DI gassers will have to meet a relaxed particle number limit of 6X10^12 particles/km starting in 2014, because DI gassers can't meet that limit at this point (and a significant number of MPFI gassers can't either)...





Source: Walter Piock, Guy Hoffmann, Axel Berndorfer, Patrick Salemi and Bernd Fusshoeller; “Strategies Towards Meeting Future Particulate Matter Emission Requirements in Homogeneous Gasoline Direct Injection Engines.” SAE International, 2011-01-1212
 
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wxman

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Excellent comparison of the gasoline 2012 Passat PZEV vs the Passat TDI. the study was based on real world testing too....
Thanks!

Those are total emissions in the well-to-wheels stage that I calculated using EPA emission factors. The second graphic serves to illustrate that even using Euro 5 exhaust emissions for the TDI, the overall WTW emissions are LOWER than the PZEV gasoline version because of the much higher well-to-pump (WTP) emissions of gasoline (and another reason why I think the U.S. should have just adopted the Euro exhaust emission standards for diesels).
 

sledstorm1

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So from this data, I am wondering how long it will take the epa to mandate particulate filter use on direct injected gasoline motors. When this happens it should level the playing field between gdi and diesels as far as production costs.
 

wxman

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Here's a graphical depiction of the particle size distributions of real-world gasoline (SI) and diesel particle emissions (taken from a CARB - *CARB* - document - Lev III PM Technical Support Document, “Development Of Particulate Matter Mass Standards For Future Light-Duty Vehicles.” Appendix P, page P65)...





The "Diesel Fleets" in the graphic are conventional diesels (no DPF). During "acceleration", the SI fleet average particle number exceeds the conventional diesel fleet almost across the entire particle size distribution field.

For reference, the following graphic demonstrates how effective DPF is compared to conventional diesel (even though the y-axis is in different units - particles/kg of fuel consumed in the first graphic; particles/cm^3 in the second graphic)...




(From Mayer et al,"Nanoparticle-Emission of EURO 4 and EURO 5 HDV Compared to EURO 3 With and Without DPF."; SAE 2007-01-1112)
 

Tin Man

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As an interesting reference, albeit from 2010, the US government looked at well to wheel total emissions of different engine types in vehicles: they don't even look at conventional internal combustion diesel to compare to but use diesel engines under the hybrid category.

There is such a bias in the US against diesels, this category isn't even looked at much of the time, it seems, even though the majority of large trucks and locomotives use it.

TM
 

robnitro

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No, but the particle emissions from gasoline engines tend to be much smaller than the particle emissions from diesels. PM emissions are currently regulated by mass in NA, and the extremely small particles from gasoline engines have almost no mass.
It is exactly the smaller particles that stay up in the air longer. That's why smog in the LA area is much higher on the weekends when less trucks and more cars are on the road.

The same smaller particles get deeper and more easily stuck in the lungs. That is what impairs lung function and gives a higher risk of cancer.

But as we all know, CARB doesn't want to know the truth. That's why they ignore the weekend effect.

As an interesting reference, albeit from 2010, the US government looked at well to wheel total emissions of different engine types in vehicles: they don't even look at conventional internal combustion diesel to compare to but use diesel engines under the hybrid category.

There is such a bias in the US against diesels, this category isn't even looked at much of the time, it seems, even though the majority of large trucks and locomotives use it.

TM
Funny, looking at that number, it is not really a diesel hybrid, but a diesel alone that easily gets that number. I suppose they put it under hybrid to hide that the diesel engine alone is cleaner than gas. There is definately some shady stuff going on!

I'm not confident about the ethanol numbers. Perhaps on CO2 it scores lower, but then- there is much less energy per gallon of ethanol.

What is also interesting is the plug in electric battery car gets similar ratings to diesel. Despite that, the electric cars are overhyped as the solution to our problems. Just like CARB ignoring the weekend effect.
 
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Tin Man

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It is exactly the smaller particles that stay up in the air longer. That's why smog in the LA area is much higher on the weekends when less trucks and more cars are on the road.

The same smaller particles get deeper and more easily stuck in the lungs. That is what impairs lung function and gives a higher risk of cancer.

But as we all know, CARB doesn't want to know the truth. That's why they ignore the weekend effect.



Funny, looking at that number, it is not really a diesel hybrid, but a diesel alone that easily gets that number. I suppose they put it under hybrid to hide that the diesel engine alone is cleaner than gas. There is definately some shady stuff going on!

I'm not confident about the ethanol numbers. Perhaps on CO2 it scores lower, but then- there is much less energy per gallon of ethanol.

What is also interesting is the plug in electric battery car gets similar ratings to diesel. Despite that, the electric cars are overhyped as the solution to our problems. Just like CARB ignoring the weekend effect.
Yes, exactly.

Don't forget, the large particles that make diesel smoke black fall to the ground and are decomposed organically, not usually making it to the lungs anyway.

TM
 

wxman

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Preliminary Particle Emissions from Gas-Hybrid Vehicles

A few studies have recently looked at real-world particle emissions from hybrids compared to conventional gasoline vehicles. One study looked at the hybrid and conventional versions of the Toyota Camry. The results may be surprising to some...

...Across 5 replicate real-world runs, the average total cumulative particle number (3 to 3000 nm particle diameter) emission rates measured for the hybrid vehicle were two times higher than that of the conventional vehicle, despite the hybrid vehicle's internal combustion engine (ICE) being off 16 to 57% of the run duration....
Robinson, Mitchell K., Holmen, Britt A., "On-Board, Real World Second-by-Second Particle Number Emissions from a 2010 Hybrid and Comparable Conventional Vehicle."


This should be considered "preliminary" since the paper has not yet been published and thus has not been peer-reviewed (as far as I know). Nevertheless, it doesn't appear that hybrids are any better (actually worse in this study) than conventional gasoline vehicles with respect to particle emissions, even when running with the ICE off part of the time.
 

wxman

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Another very recent study on gasoline particle emissions...

...In the case of diesels, the limit value necessitates the installation of very efficient wall particulate filters which have been shown to be equally or even more efficient in capturing sub-23 nm particles [41]. It is not clear however whether particulate filters will be required to control the particle emissions of gasoline vehicles. Port Fuel Injection (PFI) vehicles are generally found to emit below the diesel limit following the regulatory procedure [8], but were reported to exceed this threshold when a CPC with a lower cut-off size is employed [42]. Direct Injection Gasolines (G-DIs) were found to exceed the diesel limit by as much as one and a half orders of magnitude [8]....
Athanasios Mamakos; Urbano Manfredi, "Physical Characterization of Exhaust Particle Emissions from Late Technology Gasoline Vehicles." European Commission, Joint Research Centre, Institute for Energy and Transport, 2012 (Page 46)
 

Tin Man

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GoFaster

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That a hybrid vehicle has higher emissions than a standard version of the same vehicle, I don't find surprising. The closed-loop EFI works well and the catalyst stays lit up as long as the engine is running. Stopping the engine and starting it results in a few engine revolutions in open loop until the EFI sorts itself out again, and if the engine off period is long enough, the catalyst temperature may drop too low to light up immediately on restart.

There is no free lunch.
 

wxman

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I must confess that I was at least a little surprised that the hybrids have higher particle emissions than their conventional counterparts, the same maybe, but did not expect higher.

Toyota explicitly stated in a press release in 2010 that its Lexus CT 200h had "almost no NOx or particulate emissions" and it "generates significantly less NOx and particulate emissions than an equivalent diesel engine vehicle" (http://pressroom.lexus.com/article_display.cfm?article_id=2082). I was skeptical of the significantly-less-particle-emissions-than-an-equivalent-diesel claim (assuming they were referring to new-technology diesels engines) since diesel with DPF emits PN similar to HEPA-filtered background air even according to CARB except during regeneration, but I expected hybrid version to have less particle emissions, or at least no more, than conventional gassers.

Here are a few more references regarding PN emissions from hybrids...


...As explored earlier in this study, a large variation in frequency and duration of engine-off events occur (Robinson, 2010), and the resulting spiking of total particulate emissions resulting from the engine “restart” events leads to potential hot-spot locations where excessive emissions are observed....
Matt Conger, Britt A Holmen, "Impact of Road Facility Attributes, Congestion and Temperature upon Changes in Particulate Emission Rates Resulting From Hybrid Engine Re-start Events." American Association for Aerosol Research 30th Annual Conference, 2011, http://aaarabstracts.com/2011/viewabstract.php?paper=489


...Overall, PN concentrations, at the run level, were significantly higher under hybrid ICE-on operation compared to the conventional operation....
Matt Conger, Britt A Holmen, "Real-World Engine Cold Start and “Restart” Particle Number Emissions from a 2010 Hybrid and Comparable Conventional Vehicle." 2011, http://www.uvm.edu/~transctr/research/grad/12-4570.pdf


The link to the reference in Post #14 is http://amonline.trb.org/12k8g9/3


It should be pointed out that the PN emissions of the hybrids tested were still low (in the low 10^11 particles/km range which means that it would meet the diesel PN limit in Europe (6X10^11 particles/km)), but they aren't really "near zero" nor "significantly less than equivalent diesel engine vehicles".

On a related note...I wonder what the PN emissions of GDI with start/stop technology would be?
 
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wanabe

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In case it hasn't been posted, just as an FYI:
I noticed in my Internet travels that diesel does really well in this 2007 California study: http://www.energy.ca.gov/2007publications/CEC-600-2007-002/CEC-600-2007-002-D.PDF page 193 Figure 7-3
Wonder how much better the new "clean diesels" with the new DPF's and urea injections would look - probably fantastic!

This is a Well To Tank chart where the tank is the one in the ground at the retail station. It shows that Diesel has a head start in the total Well To Wheels computation but has nothing to do with the vehicles themselves.
 

Tin Man

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This is a Well To Tank chart where the tank is the one in the ground at the retail station. It shows that Diesel has a head start in the total Well To Wheels computation but has nothing to do with the vehicles themselves.
Uh, not really. How does a tank in the ground produce NOx and CO emissions?

TM
 

wanabe

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Uh, not really. How does a tank in the ground produce NOx and CO emissions?
TM
The tank is an end point just like the wheels in a well-to-wheels comparison.
The chart claims to be showing the emissions generated in getting the petroleum out of the well, transporting it to the refinery, refining it, transporting it to the station, etc. A well-to-wheels chart would add emissions generated getting it from the station's tank into the vehicle and using it to provide power to the wheels.
 

Tin Man

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The tank is an end point just like the wheels in a well-to-wheels comparison.
The chart claims to be showing the emissions generated in getting the petroleum out of the well, transporting it to the refinery, refining it, transporting it to the station, etc. A well-to-wheels chart would add emissions generated getting it from the station's tank into the vehicle and using it to provide power to the wheels.
That is precisely what this does/including the NOx and CO which can only be produced by the vehicles..

TM
 

Phantomofheat

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Back to the original statement about the soot in the direct gas injection. I fully believe that the issue is due to the programming of the car running on old school thought for scotch and timing. To correct the issue they need to advance spark timing to give longer burn time reducing hyrdocarbons emissions and soot. The other way to do it is inject the fuel a little sooner and leaner ~15.5 (emissions are very close to 14.7:1).

It is a balancing act depending on load and required power ~13.2:1 max power with timing advanced and 15.5:1 with timing set to reduce EGT.

I had/have my last two cars 98 bonneville and 03 grandprix running 50* advance timing at low loads constant speeds with slightly increased EGR and a larger Decel window. If I had wideband O2 I would have leaned out the fueling and could have pushed both over 30mpg hw making stock more than twice the hp and 75ft lbs more .

Sorry for the tangent at the end I just miss tuning the PCM.
 
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