[DerAlte]

Originally Posted by vina

... monitor pressure both before and after the DPF - this way they get an idea of the pressure drop across the DPF ... (it may be accumulated ash) ...

The pressure drop part makes sense, though system cost will increase (and the reliability will decrease - nullifying any gains) due to the added component. And the motto of diesel system designers is 'a penny saved = a penny earned'. Even for the costlier Truck / Bus diesel engines.

Can't reconcile with the 'ash' part, though. Where does the 'ash' come from? In boilers in powdered-coal-fired thermal power stations, one gets 'fly ash' due to the hard-to-burn silicates in the coal. But in diesel? Even the soot (mostly pure carbon) - when it burns - burns cleanly without residue. And IF there is any residue, it will be much lighter than the soot (carbon gone after burning), and will get blown away by the exhaust flow.

[amit1234singla]

Vina - are you sure Ford 1.4L Duratorq engine comes with DPF. The reason I am asking is because Ford recommends the use of their WSS-M2C913-B rated oil in this engine and a quick google search revealed that this oil is for cars w/o DPF. Please search using "Shell Helix HX7 AF 5w-30". Also, I did not find any mention of DPF in Figo diesel's manual.

Cars equipped with DPF require the use of low SAPS engine oil rated C3 (ACEA).

I believe, in India, GM 2.0L (Cruze, not sure about Optra) and VAG CR TDI 2.0L (Laura, Yeti, Superb, Passat, Audi) engines are equipped with DPF. There would be more cars with DPF (specifically from BMW and Merc). But in general, I think DPF is usually required to meet BS-IV emission norms in larger engines. Smaller diesels generally meet the norms w/o DPF.

[vina]

Originally Posted by dhanushs

...

Given the large and complex number of factors influencing the amount of soot accumulated in the DPF, and the increasingly stringent regulatory framework within current systems must operate, it is quite surprising that pressure drop measurements form the backbone of most DPF soot load measurement systems. In addition to the factors outlined above, pressure drop across the DPF is itself also a function of exhaust conditions, namely flow and temperature, DPF type and configuration, as well as the distribution and amount of both soot and ash in the filter. Confounding the issue even further is that fact that many of the most common DPF materials currently in use exhibit a non-linear initial increase in pressure drop with soot load, due to the soot first accumulating in the filter pores (depth filtration) prior to forming a layer on the filter surface (cake filtration). Depending on the filter's operating history, the pressure drop response may exhibit a significant hysteresis as a result of the relative amounts of soot accumulated in the filter pores and cake layer. Several studies have attempted to quantify the variability and error in pressure-based DPF soot load measurements, reported in the range of + 50% of the measurement"

Source: http://www.ecd.bnl.gov/pubs/BNL-77814-2007-JA.pdf

Now you can imagine the accuracy of the pressure drop measurement.

Hi Dhanush

First of all thanks for the report - though I didn't understand much of it . By the way, did you really quote from this one (or did you give the wrong link by mistake) - I didn't find "formulations" "backbone" and many other words you have used anywhere in the report. Can you check and post the correct link?


Coming to your comments - while it may be surprising why a better method is not used for ash measurement than pressure-drop (in the light of all the problems mentioned above) it wouldn't be so surprising once you realize there may not be many better options and this one may act well enough. The method used by the authors of the report (spectrometry) is neither feasible for a running engine nor cheap.

For example lambda sensors are hugely non-linear (even wide-bandwidth ones) but still used - in fact the nonlinearity can be a boon for the system - look for sudden increase in pressure drop and initiate regeneration. Same is ture with hysteresis - once the pressure drop increases it will not go away (during regeneration) until after the filter is significantly clean. In fact in electronic design both (high non-linearity and hysteresis) are frequently used on purpose to get several desirable properties (noise immunity, filtering, memory ...)


Also, with calibration the variation can perhaps be reduced substantially (calibration is already used heavily e.g. every new injector comes with a calibration code - I learned about it first on TBHP ). e.g. Every DPF will probably have some pressure drop range which can be deemed "normal" for that DPF type/brand/size/etc. That can be told to the ECU to work with using some codes etc. in this case too (and/or the OEM may specify exactly which make/model of DPF to use)

Originally Posted by DerAlte

The pressure drop part makes sense, though system cost will increase (and the reliability will decrease - nullifying any gains) due to the added component. And the motto of diesel system designers is 'a penny saved = a penny earned'. Even for the costlier Truck / Bus diesel engines.

Can't reconcile with the 'ash' part, though. Where does the 'ash' come from? In boilers in powdered-coal-fired thermal power stations, one gets 'fly ash' due to the hard-to-burn silicates in the coal. But in diesel? Even the soot (mostly pure carbon) - when it burns - burns cleanly without residue. And IF there is any residue, it will be much lighter than the soot (carbon gone after burning), and will get blown away by the exhaust flow.

From what I read in several places (TDI forum etc.) two pressure sensors, one before and one after the DPF are used in all large diesel systems. It doesn't increase cost because the after-DPF pressure measurement is needed for the catcon/exhaust anyway (I don't know why - perhaps to see if the catcon or exhaust is blocked), and measuring the two drops leads to a drop measurement across the DPF automatically.

In any case you must measure the drop, nut just back-pressure. The latter has no meaning if you are interested ONLY in DPF. For example an exhaust blockage will show very high back pressure all the way to the engine even if the friendly dishonest service station (e.g. Skoda crooks replacing their customers' car parts with dupilcates) replaced your DPF with a pipe.


Ash comes due to impurities and sometimes due to those impurities reacting with material already present in the engine/filter. The amount of ash generated once soot is burnt is very small to begin with (that is why cleaning is mandated only after 150000 miles the first time - this is an EU and US spec).

Lighter ash will definitely get blown away usually, except in case of DPF exhaust is made to flow along the walls (alternate holes are plugged at inlet/outlet faces of the filter) - the ash eventually will form a paint like layer that will be very hard to blow away. For filter cleaning I don't know exactly what they do (use some cleaning fluid perhaps) but the commercial systems available all seem to have some baking chamber (may be to help the cleaner fluid react with the ash - I don't know).

[dhanushs]

Originally Posted by vina

...or did you give the wrong link by mistake...

Alas.. I did make a mistake, and the link is wrong.

THIS is the correct link.

[vina]

Originally Posted by dhanushs

Alas.. I did make a mistake, and the link is wrong.

THIS is the correct link.

I read the whole paper - the things you quoted were from the introduction of this paper - they are way exaggerated (and finally in the last paragraph list out calibration and modelling "for balance" I guess).

Similarly the conclusions do not even mention any possible problems, though guys who have ever worked with RF can tell you several obvious ones.

While the technology they are proposing is interesting, it requires huge amount of work to be feasible (when the authors say feasible it means the technology can actually do something - it doesn't mean you can actually ever use it - reliability, cost, manufacturability, ... are never considered in this kind of studies)

I read over a dozen research papers a week (part of my job) - I can tell you this - the data will be all correct (if the paper is peer reviewed), the conclusions must be taken with a pinch of salt, and the introduction sections are pretty much useless.

[vina]

Can anyone tell me how often does the DPF regenerate when new? I read somewhere that the process is avery 1000km roughly.

also how much would it usually cost to have one replaced?

[dhanushs]

Originally Posted by vina

Can anyone tell me how often does the DPF regenerate when new? I read somewhere that the process is avery 1000km roughly.

I think DPF regeneration interval depends on the pattern of driving, fuel quality etc. ie, if you are driving aggressively on the highways, exhaust reach temperatures at which passive regeneration is possible. Where as, if you drive only sedately, and in low rpms in city, exhaust temperatures would not suffice for regeneration and hence, only regeneration would be active.

So, I guess its difficult to come to a per kilometer conclusion.

Originally Posted by vina

also how much would it usually cost to have one replaced?

Now, do you really wanna hear it?. Well, in some international forums(Ford Forum etc..) I have read the cost to be around 1000 pounds. but then, the good news is that the average life is ~1,50,000 miles.

==========================================

Also, vina, what I'm interested in is, the effects of removal of DPF. DPF is said to be a shortcut for the manufacturers to make their cars Euro 5 compliant, without really adding any tech. Hence, DPF saps the overall efficiency. Removing DPF and one is said to gain 10-15% of power and FE. However, the MIL light would be on, and ECM would throw up tantrums. Is there a way to get past it?

[vina]

Originally Posted by dhanushs

I think DPF regeneration interval depends on the pattern of driving, fuel quality etc. ie, if you are driving aggressively on the highways, exhaust reach temperatures at which passive regeneration is possible. Where as, if you drive only sedately, and in low rpms in city, exhaust temperatures would not suffice for regeneration and hence, only regeneration would be active.

So, I guess its difficult to come to a per kilometer conclusion.


Now, do you really wanna hear it?. Well, in some international forums(Ford Forum etc..) I have read the cost to be around 1000 pounds. but then, the good news is that the average life is ~1,50,000 miles.

==========================================

Also, vina, what I'm interested in is, the effects of removal of DPF. DPF is said to be a shortcut for the manufacturers to make their cars Euro 5 compliant, without really adding any tech. Hence, DPF saps the overall efficiency. Removing DPF and one is said to gain 10-15% of power and FE. However, the MIL light would be on, and ECM would throw up tantrums. Is there a way to get past it?

thanks, but if the article I read says 1000km then I would guess the regeneration should not happen no matter what you do at less than 100km


Wouldn't getting rid of the DPF also result in the soot then reaching the CatCon and destroying that? I'm not sure what can be done to get rid of MIL short of jimmying the sensors and/or the ECU

[Games Goblin]

Guys, I have a 2006 Skoda Laura 1.9 PD-TDI DSG. When decoding my VIN, the following shows up in engine info

1.9 PD-TDI 8V turbo, (DPF*) diesel 77 kW (105 PS) @ 4000 rev., 250 Nm @ 1900 rev., SOHC, EU3*-EU4

DPF is marked with * and it denotes that DPF is for EU4 vehicles, while mine is EU3

[dhanushs]

Originally Posted by vina

Wouldn't getting rid of the DPF also result in the soot then reaching the CatCon and destroying that?

Umm... I think in vehicles with DPF, there is no catcon, instead its the DOC (Diesel Oxidation Catalyst). And it is placed before the DPF.

[athalaga]

Hello Everyone,
I have been in the DPF area since 11 years both in the US and now in India. I can take any technical queries regarding all after treatment devices wrt to diesel engines.

[dot]

Originally Posted by athalaga

Hello Everyone,
I have been in the DPF area since 11 years both in the US and now in India. I can take any technical queries regarding all after treatment devices wrt to diesel engines.

What do you think of the acicular mullite technology that is being considered for new gen DPFs.

[athalaga]

Originally Posted by dot

What do you think of the acicular mullite technology that is being considered for new gen DPFs.

Ha...You work for DOW? I have worked on Mullite earlier in an research organisation.
I think it is more suitable for next gen GPF's rather than DPFs. Personal Opinion though.

[FlatOut]

Originally Posted by vina

I found this Diesel particulate filter - Wikipedia, the free encyclopedia on the wikipedia but there doesn't seem to be much on team bhp (did search with different keywords - mods please merge with the relevant thread if I missed it).

HEre are my questions:

1. Do all diesel cars have DPF?
2. What are the maintenance requirements for DPF?
3. How will it effect driving if some fault develops in DPF (blockage etc.) - basically as an average driver how can you figure out there is a problem, when to suspect a problem?
4. Can it be replaced/cleaned/maintained in a DIY?
5. anything else ...

To answer the 5th question, people in Britain are beginning to turn their backs on diesel cars because of their tremendous complexity today. The massive benefit of a diesel not very long ago was the relative simplicity compared with a petrol engine - no ignition circuits and all the associated components, no electronics, no fuel evaporation (and less danger of explosion in an accident), less engine wear over time, better economy and so on. The spark ignition engine has become more efficient and is now simpler, a complete change with how it used to be.

With the arrival of Euro4 emission regulations - and subsequent regs - the diesel engine has morphed into a hornet's nest of complexity and expense. The battery, starter motor and many other parts were always more expensive (and heavier) and a diesel required more frequent oil changes - but this was outweighed by the benefits. Today, the petrol engine makes a lot more sense unless you are regularly towing heavy trailers or are making your own fuel for a fraction of the cost of pump diesel.

[StarScream]

Originally Posted by athalaga

Hello Everyone,
I have been in the DPF area since 11 years both in the US and now in India. I can take any technical queries regarding all after treatment devices wrt to diesel engines.

Thank you. Is it true that some diesel cars in India come with DPFs? I thought the answer is no because the DPF will clog in no time with our fuel quality. And DPFs also need ultra-low sulfur diesel, which is not available in India at present. Or have I got that wrong and there is no connection between ULSD and DPFs?