(Off the wall rather than stupid question) IET exhaust fumes

[whole diary]

[Adrian]

Has anybody else noticed this, or am I the only one?

Whenever I stand on a platform alongside an IET^▸ (Intercity Express Train), I feel I'm being smothered in diesel exhaust.  For some reason the fumes seem to come off the roof horizontally, whereas from all other DMUs^▸ (Diesel Multiple Unit) and locomotives the exhaust goes upwards.

Finally got around to posting something after lurking on this forum for the last couple of years 

[martyjon]

Has anybody else noticed this, or am I the only one?

Whenever I stand on a platform alongside an IET^▸ (Intercity Express Train), I feel I'm being smothered in diesel exhaust.  For some reason the fumes seem to come off the roof horizontally, whereas from all other DMUs^▸ (Diesel Multiple Unit) and locomotives the exhaust goes upwards.

Finally got around to posting something after lurking on this forum for the last couple of years 

Welcome to the forum Adrian, I am sure the moderators will extend their greetings to you also.

[IndustryInsider]

Welcome to the forum.  I can’t say I’ve noticed the phenomenon you describe though.

[stuving]

Indeed, Adrian, welcome. Your post reminded me that I had never worked out exactly where the engine exhausts were in IET^▸ (Intercity Express Train) cars with engines. So I have gone back and had another look, and I can see what must be one right on one of the corners. I have a picture I can post, but I don't think it will be visible to everyone (and not to Adrian, unfortunately) - if anyone can find a published picture from above to link to, that would be very helpful.

I did find something about the makers of the pipe, Eminox, who are based in Lincolnshire. They say this about it:

Eminox was set the challenge of developing a bespoke exhaust system to transfer gas from the after treatment system located underfloor next to the engine, through the car body to the rear, and ensure safe discharge from the top of the train. The system had to fit a narrow space envelope with a complex routing though the structure.

The solution incorporates 16 metres of pipework from Ø5.5” to Ø8” (140 x 200mm) and which is manufactured entirely from stainless steel. The design incorporated insulated pipes, convolutes, bellows and mounting brackets.

I must say I'd not noticed the effect you describe, and in any case the exhaust of these engines is required to be a lot cleaner than previous ones (and compared to an HST^▸ (High Speed Train) ...). The exhaust processing to meet NRMM IIIB is not actually called BlueTEC by MTU^▸ (Motor Traction Unit), nor is Daimler credited, but it does involve "SCR system, exhaust muffler with catalyst, ADBlue injection with supplying and metering unit" which sounds like BlueTEC. SCR is a selective catalytic reduction, and Adblue is mostly urea - can you detect that in the exhaust? As I said, I'd not noticed the exhaust so I couldn't say.

[Adrian]

Interesting.  I think I'd expected that the 'cleaner' exhaust from an IET^▸ (Intercity Express Train) would mean there would be less smell than from older diesels.  However, given the treatment process you describe, perhaps the converse is true?  I'll pay attention to what it smells of - whether there's a hint of urea - next time I'm standing alongside one.

[Fourbee]

From the photo the exhaust stack on a class 166, say, seems higher, but it may just be the perspective.

I was sitting on the pull-down seat in the vestibule of a rammed 159 the other day and there seemed to be a strong smell in there; may have been someone's contribution to the lavatory, but seemed exhausty.

[stuving]

This is the only picture I can find that looks down, and even then it's an awkward perspective (and it's an 800, mine was an 802, as you can see).

(This is a Hitachi picture, but there is a clearer view on this blown up version of the middle of it, which has somenoe's copyright claim on it.)

One of the exhaust outlets is visible on the front corner of the second nearest carriage, the other two are on the far corners of the two behind it and not visible (not clearly anyway). I think you can see that there is no obvious source of an air stream that would push the exhaust off sideways, the chiller unit being the main thing that might be one. Of course how the air flows in a particular station, with a load of big fans pushing air upwards, is another matter.

One thing I have noticed is that, even when on electric, the sheer number of big cooling fans in the assorted machinery crammed into the shallow lockers under the floor makes it almost as noisy as on diesel power when accelerating out of a station.