[Traindude]

I have a question about the BoilerVolume .eng file parameter.

Obviously the most important aspect of this parameter is the volume of the boiler barrel proper (minus the space occupied by the tubes and flues. However, if we're going for accuracy the BoilerVolume parameter should, theoretically, include the volume of the water space surrounding the firebox, and, if a locomotive is so equipped, the combustion chamber and any arch tubes, circulators or syphons in the firebox.

However, even if you have the exact drawings of the boiler on the locomotive in question, calculating the volume of these areas is not easy unless you're a good mathematician.

So my question is this: Is including the volume of water space around the firebox, combustion chamber, arch tubes, circulators and syphons really necessary or not?

[Genma Saotome]

I may be wrong about this but my recollection is boiler volume isn't important, but evaporation area is -- the sum of the surface area of all tubes, superheat, and useful portions of the firebox. Those surfaces boil water; The volume of water that has yet to boil isn't important as far as performance goes.

Maybe MSTS/OR do something different but I cannot recall ever coming across boiler volume in any of the technical journals I've found.

[darwins]

Traindude, on 19 January 2023 - 09:45 PM, said:

I have a question about the BoilerVolume .eng file parameter.

Obviously the most important aspect of this parameter is the volume of the boiler barrel proper (minus the space occupied by the tubes and flues. However, if we're going for accuracy the BoilerVolume parameter should, theoretically, include the volume of the water space surrounding the firebox, and, if a locomotive is so equipped, the combustion chamber and any arch tubes, circulators or syphons in the firebox.

However, even if you have the exact drawings of the boiler on the locomotive in question, calculating the volume of these areas is not easy unless you're a good mathematician.

So my question is this: Is including the volume of water space around the firebox, combustion chamber, arch tubes, circulators and syphons really necessary or not?

Ideally yes, however an approximation is fine.

If I remember correctly the main purpose of boiler volume has to do with heat capacity - a bigger volume will change more slowly and a smaller volume will be more responsive to firing, but store less heat.
I have a boiler volume calculation spreadsheet, you might like to consider adapting and improving. The results are approximations, but they are close to measured values where they exist.  Boilers.zip (335K)
Number of downloads: 82

[Paul B]

Hi all;

I think boiler volume is also important in determining water consumption. Or more accurately how quickly the water level in the boiler drops as steam is consumed.

On an engine with a big boiler and relatively small cylinders the water level in the sight glass would drop slower compared to a loco with a small boiler and relatively big cylinders (eg a shunting/switch engine)

As real world data is hard to come by, and the figure is really an estimate.

Cheers;

-Paul

[Lamplighter]

Here is the method I use:

I distinguish whether it is a tender locomotive or a locomotive with a towed tender.
If it is a tender locomotive, I will use this relationship:

(A-(B+C+D))x1,4

where:
A = Locomotive service weight in tons (fully loaded with coal and water)
B = Water in the tender (capacity) in tons
C = Coal in the tender (capacity) in tons. Sometimes the volume of the tender is given in cubic meters. Then it is necessary to calculate the weight of the coal from its bulk weight - black, brown or a mixture.
D = Weight of an empty locomotive in tons
These values are usually readily available in locomotive technical descriptions.

In the case of a locomotive with a towed tender, I will use the relationship:

(A-D)x1,4

The result is the approximate volume of the boiler in cubic meters.
Since I use dynamic load settings for steam locomotives, I further manually correct the result according to the locomotive weight data in the HUD.