[Jean-Paul]

Hello !
I've made first tests with new version 1.3.1.162, around improvement in steam heating. After having experimented various values of the new parameters (and it was not easy !), I had rather good results with my test train (4-6-2 BR Peppercorn A2 + 8 MkI passenger coaches ). Temperature was correctly sustained, with a correct steam consumption. But... (I know, with me, there's always a 'but"..! :sign_sorry: )
I decided to try with a longer train : 14 coaches, of the same type (BR MkI), and same parameters. And there, I could notice that steam consumption was unable to stabilize, oscillating without any stop from 200 lbs/h up to 1800 lbs/h, with as a major effect an unefficient heating. No problem with steam engine, whose steam production is widely greater (around 34000 lbs/h). I don't know what could be the origin of this problem, but, often, it may be observed when calculation process is "saturated" by defective or too complex equations.
To be more precise, it seems that calculation model could support up to 11-12 coaches before "flickering"...
If anybody has an explanation ?
Heating parameters were :
ORTSHeatingWindowDeratingFactor ( 0.25 )
ORTSHeatingCompartmentTemperatureSet ( 20 )
ORTSHeatingCompartmentPipeAreaFactor ( 1.2 )
ORTSHeatingTrainPipeOuterDiameter ( 6in )
ORTSHeatingConnectingHoseOuterDiameter ( 7in )
ORTSHeatingConnectingHoseInnerDiameter ( 3in ) (with a "PipeAreaFactor" <1 calculation problems appeared with 9 vehicles)
Thanks for your help !
Cheers,
Jean-Paul

[darwins]

Hi Jean-Paul


Having carried out a lot of experiments during testing I can make the following comments.


Large fluctuations happen under two sets of conditions, either:


( 1 ) Temperature is achieved in some or all of the vehicles and the thermostat shuts down the heating - although steam consumption fluctuates, the overall effect is reasonable - further experiments are needed for this but particularly if there are slight variations in ORTSHeatingWindowDeratingFactor and ORTSHeatingCompartmentPipeAreaFactor and possibly also ORTSHeatingCompartmentTemperatureSet carriages which were all switching on or off together should move out of sync and spread the fluctuations. Importantly temperature in the rear car is maintained.


( 2 ) The steam requirement of the train is beyond that which can be supplied - either because the locomotive can not provide sufficient steam - not a problem with the A2! or because the plumbing does not allow sufficient steam to reach the rearmost car of a long train - which is your problem above. In this situation not only does steam usage sometimes become very high, but in the rear vehicle in sometimes falls to zero and in this case the temperature will drop.


One way to overcome this is to increase the size of the steam pipe ORTSHeatingTrainPipeInnerDiameter and another way is to increase the supply pressure from the locomotive. In the USA they used both, with 2.5 inch bore steam pipes and pressures up to 250 psi. These will solve your problems above.


To make a more realistic solution using British values the following should work for up to 16 Mark 1 coaches.

ORTSHeatingCompartmentTemperatureSet ( 18 )
ORTSHeatingCompartmentPipeAreaFactor ( 2.0 )
ORTSHeatingWindowDeratingFactor ( 0.25 )
ORTSHeatingTrainPipeOuterDiameter ( 2.75in )
ORTSHeatingTrainPipeInnerDiameter ( 2.00in )
ORTSHeatingConnectingHoseOuterDiameter ( 2.25in )
ORTSHeatingConnectingHoseInnerDiameter ( 1.75in )

For BR steam heated carriages I would suggest values of ORTSHeatingCompartmentPipeAreaFactor between ( 1.5 ) and ( 2.5 ) with lower values for First Class (more radiator area) and higher values for brake vans. Older British carriages would have used less steam for heating and would have values between ( 2.0 ) and ( 3.0 ). Only in countries with extreme climates would lower values be realistic. For the final US steam heated stock with 2.5 inch steam pipes and 250 psi supply pressure then values between ( 0.5 ) and ( 1.0 ) might be realistic.

For your A2 I assume you are using MaxSteamHeatingPressure ( 60psi ) which was the standard BR value and also the final LNER value for large passenger locos.

Finally a note that the ambient temperature in OpenRails and MSTS is based only on latitude - so most British routes will be colder than most US routes in winter snow.

[Jean-Paul]

Hello !
Many, many thanks for these precious informations : I'm going to test this !
:sign_thanks:

Cheers,
Jean-Paul

[Laci1959]

Hello.

Is the ORTSHeatingWindowDeratingFactor the ratio of the side area of the car to the window areas on it?
ORTSHeatingTrainPipeOuterDiameter >> Do you think this is not a through-steam line with 50-60 mm thick insulation running under the car?
ORTSHeatingTrainPipeOuterDiameter >> If this is the heating steam line running in the car, is it the actual diameter of the pipe or the diameter of the radiant surface consisting of plates strung on the pipe? The plates are brazed to the pipe at a distance of 25mm.

Sincerely, Laci 1959

[steamer_ctn]

 Laci1959, on 18 December 2021 - 02:48 AM, said:

Is the ORTSHeatingWindowDeratingFactor the ratio of the side area of the car to the window areas on it?

Correct.

 Laci1959, on 18 December 2021 - 02:48 AM, said:

ORTSHeatingTrainPipeOuterDiameter >> Do you think this is not a through-steam line with 50-60 mm thick insulation running under the car?
ORTSHeatingTrainPipeOuterDiameter >> If this is the heating steam line running in the car, is it the actual diameter of the pipe or the diameter of the radiant surface consisting of plates strung on the pipe? The plates are brazed to the pipe at a distance of 25mm.

This is the pipe that carries the steam along the train.

The outer diameter includes any insulation fitted around the pipe.

[Laci1959]

 steamer_ctn, on 22 December 2021 - 01:24 AM, said:

This is the pipe that carries the steam along the train.

The outer diameter includes any insulation fitted around the pipe.

Hello.

Thanks for the help. I will be able to determine the surface of the arched roof using AutoCad. This data is almost identical for UIC B70 cars, so it only needs to be edited once.

Then this pipe will not heat as it is insulated. It has about the same function as the second air tube (filling tube) at the brake. It transfers the steam to the next car. If this is true then its diameter should not affect the heating. This is contrary to the wording described in the Manual.
With us, the pipe that leads to the radiators branches off from this pipe and has three-position taps in the passenger compartment. I remember this tap well from my childhood.

Sincerely, Laci 1959