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Do Diesel particulate filters really work?
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Gloomendoom wrote: »My car has a DPF and the inside of the tailpipes are spotless. I don't think it makes much smoke, if any at all.
This. No longer do modern diesels do what the pre-DPF ones do and have a black patch on the rear bumper around the exhaust.How does the PDF get hot enough to ignite the deisel fuel to clear the DPF?
Remember diesel engines have no spark plugs to ignite the fuel. Diesel manages to be ignited by the temperature increasing in the cylinder as the air/fuel mix heats up as it is compressed so it isn't beyond the realms of belief to think that they couldn't ignite diesel fed into a component that is right next to the red hot turbo being fed by red hot gases that have just been thrown out of the cylinder.This is a system account and does not represent a real person. To contact the Forum Team email forumteam@moneysavingexpert.com0 -
sevenhills wrote: »How does the PDF get hot enough to ignite the deisel fuel to clear the DPF? I assume the DPF is linked to the exhaust, once the deisel is burnt in the engine, it surely cannot reignite in the DPF/exhaust?
Read this.
https://dspace.lboro.ac.uk/dspace-jspui/bitstream/2134/4837/1/law.pdf
It should make everything clear.0 -
Gloomendoom wrote: »Read this.
https://dspace.lboro.ac.uk/dspace-jspui/bitstream/2134/4837/1/law.pdf
It should make everything clear.
Ah this cleared it up! Simples!
(1−Q)rScPSAqTS qtB=∑ i R ˙ ∞∞∞ i Hi+ha[TG−TS] on the particle surface and particle shrinks in size as oxidation proceeds. One the other hand, a unity reaction order means that the reaction rate is +kSAq2TS qz2B
:rotfl::rotfl:Mr Generous - Landlord for more than 10 years. Generous? - Possibly but sarcastic more likely.0 -
sevenhills wrote: »These filters are just that, a filter. So any soot going into it will just clog up the filter, eventually.
That does not happen, because when doing motorway driving, they reach a certain temperature and preform a regeneration, meaning the heat up and expel all the soot. So all the soot that was stored, is pumped back out again, making the DPF pointless.
I always assumed it worked that way to just keep it all in during urban driving, so 1000's of vehicles in slow moving city centres don't spew out harmful particles where there are 1000's of pedestrians about, and then expel it mainly on motorways where it is more rural and open, and higher speeds mean its spread over a wide distance and can disperse easier..0 -
misterbarlow wrote: »I always assumed it worked that way to just keep it all in during urban driving, so 1000's of vehicles in slow moving city centres don't spew out harmful particles where there are 1000's of pedestrians about, and then expel it mainly on motorways where it is more rural and open, and higher speeds mean its spread over a wide distance and can disperse easier..
Slight flaw in that, there are several Motorways that run through fairly densly populated areas.
Plenty of dual carriageways also where a DPF could regen.Censorship Reigns Supreme in Troll City...0 -
forgotmyname wrote: »Slight flaw in that, there are several Motorways that run through fairly densly populated areas.
Plenty of dual carriageways also where a DPF could regen.
Well in general I meant. Obviously there are exceptions...0 -
misterbarlow wrote: »Well in general I meant. Obviously there are exceptions...
It doesn't really matter as that isn't how they work.0 -
Out of idle curiosity I monitor my van dpf statistics. Soot, ash and stuff. If it gets close to the higher end of limits I'm looking forward to having a go at a forced regen.
Things will get very hot apparently and parking in an open area is recommended!
An oil/filter change afterwards might not be a bad idea?
I've poked around underneath for a dummy run dpf change, looks easy enough.Funnily, i've been pondering a small Caddy sized van to facilitate a side project i'm going to work on. I havent seen much movement yet, but in theory markets like pickups and vans are likely to be hit by the upcoming downturn.Would be interesting to hear if anyone has direct experience?Why? So you can argue with them?0 -
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Lots. Soot & ash in grams. Loads of percentages of stuff.....? Differential pressures of more things....? Distance and time since last service regen. Temperature of x & y......etc.sevenhills wrote: »What do the sensors tell you?
I only look at the ash content really.....40g is limp territory, 60g is fubarred I think?Funnily, i've been pondering a small Caddy sized van to facilitate a side project i'm going to work on. I havent seen much movement yet, but in theory markets like pickups and vans are likely to be hit by the upcoming downturn.Would be interesting to hear if anyone has direct experience?Why? So you can argue with them?0
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