I was just reading about natural gas locomotives and saw some pictures of the locomotive consist. I must say, they looked pretty sharp. (Really enjoyed the CN, but BNSF had a green and white Burlington Northern heritage scheme that made my jaw drop...)
Anyway, has anyone modeled these? Do any manufacturers produce these? I model in N scale and I doubt anyone makes one (heck, nobody evens makes a Genset loco in my scale), but I have done plenty of scratch builds... does anyone have some prototype info, links or diagrams that I could reference? As always, any help is appreciated. Cheers!
There are two basic 'flavors' of fuel: CNG, which compressed the gas to fairly high pressure at ambient temperature, and LNG, which liquefies it to much better energy density but requires careful cryo. Most of the visible difference in the locomotives themselves will likely be slight; there are great difference in the details of the 'fuel tenders' that make natural-gas mainline power possible, and in the type of fuel connection to the engines.
If you contact Ross Rowland, he may be able to give you specific guidance as he put together a competent team to develop CNG as a working alternative locomotive power only a few years ago.
As an aside, in the absence of relatively expensive chemical promotion or esoteric forms if initiation, a large locomotive engine running on natural gas historically required either some form of timed ignition (e.g. spark as in Caterpillar dedicated natural-gas engines) or about 5% diesel co-injected with the gas.
Expect some fuel-heating concerns for both types -- particularly for operation at equivalent of Run 8 with LNG in winter weather...
I model the BNSF in N scale aswell and have an LNG fuel tank car that I scratch built. I run it between two engines that run rear to rear.
Ira
What did you use as a prototype reference? Did you just use pictures or were you able to find specs for the tender somewhere?
Unfortunatly no specs for the LNG tank car are available. I used as many pictures of the car as I could find on the web. There are quite a few and I enlarged them to be able to get the details correct.
Caldreamer
Overmod there are great difference in the details of the 'fuel tenders' that make natural-gas mainline power possible,
What would the differences be as far as tender details are concerned?
If you saw a natural gas fueled FedEx truck, there are only very minor details that are different from CNG to LNG.
On a railroad fuel tender, the LNG tender could be smaller. LNG would also require a vent pipe, access door for the vaporizor (likely), The refueling ports would be different, but I am curious what would be the "great differences in details".
LNG fuel is heavier, but the tanks are lighter, so that could be a wash.
-Kevin
Living the dream.
SeeYou190What would the differences be as far as tender details are concerned?
Personally, I'd think a modern LNG installation would use multiple forms of nanoinsulation, so the tank size would be comparable to CNG internally; that would have consequences for the weight. Of course the external tank dimensions would be governed by loading gage and hence might be less distinguishable externally.
In the sense that a fuel tender looks like a big cradled tank serving a couple of cabs-out bookend locomotives, no, there need be not that much visible difference, much as a NYC J-3a with an ATSF smokebox front, boilertube pilot, and air-pump shrouds might not be visibly different from a 'stock' version at a distance. And in a sense it's probably not in most modelers' interest range to get all the little technical details of prototype implementation perfect.
OvermodThe difference between a cryoinsulated tank and a high-pressure vessel would likely be substantial. The piping arrangements and connections for liquid cryo are completely different, including the connections for filling and the signage and warnings. LNG will have arrangements for boiloff that CNG does not require.
Would this all be under the tender shell? In a natural gas vehicle it is all in a box either behind the cab or under the floor. Natural gas refuse trucks and city buses have the tanks on the roof, but I an unaware of any of these that use LNG.
None of the differences in tank design, installation, or plumbing are visible in a truck. I cannot imagine the tanks would be visible on a train.
You need a sharp eye to tell a CNG truck from an LNG truck. You have very few clues. There is the vent pipe on LNG (for boil-off) which is only visible from the top. Most CNG trucks have an Agility box under the cab lablelled "Gas Shut Off Inside". The fill ports are different, and the warning decals are not the same.
CNG trucks also have a vent pipe for tank safety release from over-pressurization, but it is slightly different in design and placement.
Most LNG trucks have an extra access door for the vaporizor, but that detail depends on maufacturer preference. For example, Peterbilt 330 series trucks use a door that is already there, but repurposes the compartment.
Unless the fuel tender is built on a flat car something like a USN helium car, the differences would not be substantial. Maybe barely noticeable.
It may have occurred to you by now that this discussion is about locomotive consists, not trucks. The two are not comparable in most respects. The energy density is much less, and the required range between refueling vastly greater, and the lack of suitable infrastructure at present (either fixed or mobile) so constrained that all the current actual road power requires a fuel tender -- most commonly provided as a minimum consist (2 reasonable hp locomotives) as noted sharing a common reservoir. Since absent laser ignition or other comparatively exotic oromotion and ignition of cryomethane or other light constituents is difficult, the 'state of the art' is still to co-inject some small percentage of diesel fuel or a formulaically-comparable equivalent, in the range of 5% by stoich composition, and the diesel tanks on the locomotives therefore have to be reserved.
By far the best approach for cryo, which is the development line I'm interested in, is to provide the entire cold system right up to final conditioning in a 'module' that will fit something like a single well car. (You would obviously gain by adding modules to increase the range or sustained in-service time, but no experiment has yet extended that far. I have championed the provision of MATE/road-slug like motoring under dedicated fuel tenders but, again, no experiment I have seen so far has implemented this.
The general requirements for cryomethane fueling of various types of combustion engine and fuel cells have been long established; the only real difficulty is the degree of preheat at various stages needed for a given fuel-control system... some of which can be heating on the locomotives. Modeling this 'properly' would be done from knowledge of the fuel parameters 'out', unless you specifically know what to look for on the prototype photos.
OvermodIt may have occurred to you by now that this discussion is about locomotive consists, not trucks. The two are not comparable in most respects.
The two are very comparable, especially where portable fuel storage is concerned.
Whether a truck loses its sleeper to acomodate the additional tank space for natural gas, or a train pulls a fuel tender, the requirements for fuel storage are entirely similar.
My question was simply... What are the major differences between a LNG fuel tender and a CNG fuel tender?
You mentioned there would be serious differences, and I am curious about what they would be.
All I know of are the differences in gas venting. Other than that, all the differences are markings, or beneath the shell (hood if you will), unless the tanks are actually visible, which would be weird.