Exhaust traps & emissions

[Steveminor]

Also look at the amount of pollutants per person (capacity) & buses are much more environmentally friendly than most cars on the road.

[barry619]

Anyone know the technology behind these traps you'll know they only burn off diesel particles if the engine has been running fast (at speed, motor way driving whatever) for a while (1hr or around).

DPFs burn the soot off either when the engine is run 'hard' and the exhaust gas temperature is high, or by use of an injector within the exhaust. This injects diesel which is burnt inside the exhaust to generate sufficient heat and is know as 'active regeneration'. Active regeneration is not favoured in buses as it leads to a huge amount of heat coming out of the exhaust pipe - not a good scenario in city centres and other urban areas. The economics of using diesel for anything other than powering the bus are also dubious at best, although I believe an active regen is much rarer than it was originally suggested they would be.

Soot is meant to be burned off, but ash also accumulates in the filter. This cannot be burned off and once there is so much of it in there, the filter needs to be cleaned. The presence of DPFs in Euro 6 buses is one of the reasons why engines have been downsized so much; they must work a lot harder than a 10- or 11-litre unit would, and so generate more heat to help the DPF work correctly. The exhaust size is also proportional to the engine size.

A blocked (even partially) DPF is not a good thing as it creates backpressure within the exhaust, worsening fuel efficiency. One full of soot is even worse, as it can potentially catch fire when the engine finally is run hard and destroy the filter at substantial cost.

The retrofit systems to bring older buses up to Euro 6 from Eminox, a Swiss company and one or two others use a DPF but also install an Ad-Blue dosing unit into the exhaust to deal with NOx. I haven't seen the others up close, but the Swiss installation is very slick.

[Liverpool Street]

Thank you for you that @barry619 - it all seems very dodgy for an oldschooler like me
      I'd rather the EU leave us well enough alone and I am dubious that global warming isn't a money making scheme by said governing body.

I'm not denying that global warming occurs naturally; maybe they're pushing it a bit harder then how bad it actually is.

Do you legit think the world would let itself get done over

[Stuharris 6360]

Thank you for you that @barry619 - it all seems very dodgy for an oldschooler like me
      I'd rather the EU leave us well enough alone and I am dubious that global warming isn't a money making scheme by said governing body.

I'm not denying that global warming occurs naturally; maybe they're pushing it a bit harder then how bad it actually is.

Do you legit think the world would let itself get done over

I certainly think it's a money making scheme for bus manufacturers @Liverpool Street , what's to say when a lot of operators are using Euro VI engines, that a EuroVII one won't be developed!

[Liverpool Street]

I certainly think it's a money making scheme for bus manufacturers @Liverpool Street , what's to say when a lot of operators are using Euro VI engines, that a EuroVII one won't be developed!

Does seem a bit dodgy but alas, that's the world now a days
   Saying that remember Rover developing cars with built in faults which weren't covered under warranty.
And then there is those other manufacturers who made things too good and people wouldn't sell thier cars because they're solid!!

You can't win. But still, they keep moving the boundaries, can't cars be diverted away from the city centre instead? Oh wait... Car parks...........

[Stuharris 6360]

Does seem a bit dodgy but alas, that's the world now a days
   Saying that remember Rover developing cars with built in faults which weren't covered under warranty.
And then there is those other manufacturers who made things too good and people wouldn't sell thier cars because they're solid!!

You can't win. But still, they keep moving the boundaries, can't cars be diverted away from the city centre instead? Oh wait... Car parks...........

And then there is Volkswagon, although I am sure that if the truth is known, there are other manufacturers out there who have done the same.

[Liverpool Street]

And then there is Volkswagon, although I am sure that if the truth is known, there are other manufacturers out there who have done the same.

Sort of ironic in VW's position. They fitted these exhaust traps to get cheaper yearly tax and such, and yet when they went for MOT it was software which fixed the result anyway, surely that means that the DPF meant nothing
... @Stuharris 6360

[Stuharris 6360]

Sort of ironic in VW's position. They fitted these exhaust traps to get cheaper yearly tax and such, and yet when they went for MOT it was software which fixed the result anyway, surely that means that the DPF meant nothing
... @Stuharris 6360

You never know @Liverpool Street, maybe these trap things are just a red herring and the buses software is just altered to make it seem that emissions are lower, these days nothing would surprise me.

[Liverpool Street]

You never know @Liverpool Street, maybe these trap things are just a red herring and the buses software is just altered to make it seem that emissions are lower, these days nothing would surprise me.

I honestly wouldn't put it past them @Stuharris 6360 .

Literally it seems everything can be done on computers these days regarding performance and emissions ..

Only thing is just if they get caught then it'll cause issues.

Even so I don't see why buses aren't excluded somewhat from stringent measures like these, they are mighty machines but surely a larger, less laboured engine is better than a strangulated smaller unit with a massive turbo and endless filters which use tricks to burn off soot and all that ..

I'm still old school when it comes to this really . I'd like to see the true, real day to day difference to MPG between older less laboured , say , garderner unit to these computered slave 6 liter turbo things .

Didn't you have the actual figures @Tony as I'd like to know how much 1 or 2 mpg means in company spendature in real terms ..

[Stu]

I certainly think it's a money making scheme for bus manufacturers @Liverpool Street , what's to say when a lot of operators are using Euro VI engines, that a EuroVII one won't be developed!

It's not a money making scheme for bus manufacturers as they don't set the standards; Euro 4, Euro 5 etc are all European emissions standards, regulated and defined by the EU.
https://en.wikipedia.org/wiki/European_emission_standards

[barry619]

Thank you for you that @barry619 - it all seems very dodgy for an oldschooler like me
      I'd rather the EU leave us well enough alone and I am dubious that global warming isn't a money making scheme by said governing body.

It's important to remember that the Euro scheme (all the way to Euro 6) is not aimed at global warming. CO₂ production is directly relative to the amount of fuel burnt, and the various Euro emission legislation does not have any connection with a bus' CO₂ emissions. Rather, it is concerned with NOx and particulate matter, and the nastiness of NOx (oxides of nitrogen) in particular should not be underestimated. It is a killer, make no mistake about it, and diesel engines are the main culprit. This is one of the reasons why gas power is seeing a minor resurgence; gas doesn't produce NOx at all, and it is expected that when the winners of the government's latest funding round for low-emission buses are announced next year that gas will do well.

The other benefit of gas is that thanks to some well-oiled funding arrangements with the likes of the Gas Bus Alliance, it stands up commercially - unlike hybrids and full electric...

It has been suggested that there will be no Euro 7. Rather, there will be more emphasis on the bus' CO₂ emissions and a 'labelling' system will be introduced a la tyres. Of course, nobody knows for sure, but one of the large engine manufacturers takes the view that this will happen.

I certainly think it's a money making scheme for bus manufacturers...

It absolutely is not a money making scheme for bus and coach manufacturers and you could not be more wrong in thinking that.

They have had to invest millions in redesigning vehicles, testing them and homologating them for Euro 6. It's not just engines which have had to be substantially upgraded/redesigned altogether; as Euro 6 needs to run hotter, cooling systems have had to be beefed up, space has had to be found for the chemical plants which masquerade as exhausts, the legally mandated on-board diagnostics have had to be accommodated... the list goes on. Of course, all those costs are passed on to the buyer, but to think that the likes of ADL, Wrights, Volvo and the various other builders are making more money out of Euro 6 is pie in the sky.

[2900]

Excellent thread, good debate, welcomed relief from such crap on other threads.

[Cheese]

Excellent thread, good debate, welcomed relief from such crap on other threads.

Couldn't have put it better myself. Some excellent information from @barry619 about how the whole Euro engine debate works, proper facts, not just the usual uninformed rubbish.

[barry619]

Yer welcome @Cheese.

[barry619]

Looks like I may be right in my prediction of gas doing well when the forthcoming LEB fund announcements are made. If Nottingham City Transport gets what it wants it will take 82 Enviro400 Scania gas 'deckers over three years...

https://www.nctx.co.uk/2015/11/nottingham-city-transport-bids-for-government-funding-for-25-5m-project-to-introduce-82-gas-double-deckers-to-the-city/