Diesel locos at high altitudes.

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Diesel locos at high altitudes.

Postby ben_issacs on 07 Apr 2018, 08:47

Folks,
I'm well out of touch with Chinese diesel-engined locos, and would be interested to know what special arrangements, if any, are applied to the locos on the line to Tibet, to allow them to operate efficiently at high altitudes.
Internal combustion engines are air breathing, like humans, and so don't work so well at high altitudes.
Are the engines standard designs de-rated, which was often done for the South American mountain lines?
Regards,
Bill,
Melbourne.
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Re: Diesel locos at high altitudes.

Postby roco on 08 Apr 2018, 14:48

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Re: Diesel locos at high altitudes.

Postby ben_issacs on 09 Apr 2018, 00:24

Roco,
Ta, much for that useful info. and the two web sites.
Didn't realise that the Chinese were using North American locos there.
What would Chairman Mao say to this?
But the GE website doesn't say what the actual engine horsepower output is at 5,000m altitude.
I wonder if the Chinese railways would have to recruit crews from the local, acclimatised population for that run?
Many of the railway workers on the high altitude South American lines were from the local Indian tribes, who were well used to working at such altitudes.
When we went over Condor summit in Bolivia, some 4,000 plus m, in 1975, we did it without the need for oxygen, but we had come up from Lima at sea level in stages and so were acclimatised, but one still had to move slowly or one soon got badly puffed out.
Regards,
Bill,
Melbourne.
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Re: Diesel locos at high altitudes.

Postby roco on 09 Apr 2018, 11:45

The chinese have more amerikan engines running on their tracks . In 1984-1986 the dilivered over 400 dieselengine GE 36-7 ( ND5 ) and in 2005-2006 78 pieces NJ2 .
Well I like to know it too . It can be a normal diesel that sucks less oxigen than on the lower level . Perhaps they injekt less diesel into the engine . Or they must have more turbochargers for that purpose .
Perhaps someone of GE can tell it .

wkr Jos
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Re: Diesel locos at high altitudes.

Postby ben_issacs on 10 Apr 2018, 00:24

Roco,
Yes, with diesel engine operation at high altitudes, one can reduce the amount of diesel fuel injected in proportion to the lesser amount of air taken in due to the lower pressure.
This is called 'de-rating', and has been the usual method used in South America for many years.
This, of course, reduces the horsepower output of the engine.
Another alternative is to alter the turbocharger to kick more air in.
This can be done by either with a larger turbocharger running at the same speed as the original unit, or a speeded up original sized unit.
Both of these schemes require alteration to the original design, which may have been done with the Tibet locos.
Interestingly, steam locos are not affected by the low air pressures to the same extent, it's easier to increase the amount of oil fuel injected and air intake on steamers than for internal combustion engines.
Perhaps we might see QJ class steamers on this line?
Ha! Ha!
Regards,
Bill,
Melbourne
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