It’s been so long since an update on this locomotive that I couldn’t find the previous posts easily.
Indiana Railroad 1919 (article by Vantuono in Railway Age)
I am not happy when the senior editor and any proofreaders try to mention “load temperature aftercooling” radiators in technical content. Makes me wonder how much more than press releases they’re reading, or how much press release content they’re comprehending.
The article states that the engine would have 42 percent lower heat rejection than medium speed (900 rpm) engines.
Any thoughts why this would be?
The Cummins “K” engine seems to have a lot of variation within different engines:
The QSK 19, widely used in Genset units is an I6, 159mm x 159mm, 700HP
The QSK 60 is a V-16 159mm x 170mm, 2700 HP
The QSK 78 is a V-18 170mm x 190mm, 3300 HP
The QSK 95 is a V-16 190mm x 210mm, 4400 HP
The V-12 version of the “95” would be a QSK72 of 3300 HP
The V-20 version would be a QSK120 of 5500HP
I’d guess the QSK 72 would be cheaper to build than the V-18 QSK 78…
Speaking about lower heat rejection, if this general statement were true, surely the original radiators on the SD9043MAC which were designed for a 6000 HP four stroke engine would have been suitable and retained.
Or maybe I don’t understand what they are saying…
M636C
Most of the energy in the fuel can only end up as useful work, in the exhaust, or is rejected. The article claims the Cummings engine is 7 percent more fuel efficient than modern medium speed engines while rejecting 42 percent less heat. A realistic mumber would be more like three or four percent less heat rejection, assuming the 7 percent efficiency improvement is real.
It’s better to look at technical ‘collateral’ than details that have been quoted out of context in an article whose author is unfamiliar with low-temperature aftercooling.
See this Cummins patent for some discussion on the principle their approach to LTA uses. (This patent is for a key component in that approach.)
I suspect the engine design is also made to minimize heat rejection from the actual combustion gas to coolant (and probably to the exhaust manifolding structure ahead of the turbochargers) in order to maximize heat to the turbocharging turbines. This was one of the reasons Ford was experimenting with ceramic/cermet liners and coatings for light diesels in the '70s.
On the other hand, there’s a balance between charge-air density and recovered (Rankine-cycle-like) charge heat as far as power density in the engine is concerned. Some engines with twins or triplets use very high boost pressure to increase charge density without having to ‘throw away’ the compression energy, but beyond a fairly limited range of overpressure that is not really practical and perhaps never will be for railroad engines. I think Cummins has already taken a bold step in running the railroad-size QSKs at 1800 instead of 1500rpm.
Is there ANYONE on this forum more in love with the sound of his own voice ??
CPM500
Their Voice, or their Keystrokes?
Remember the medium here. [:)]