[steamer_ctn]

With the release of X2349, a small enhancement has been added to the steam locomotive code to allow the inclusion of a customised boiler efficiency curve to be read from the ENG file.

For further information on it, see here for further information.

[cjakeman]

Hi Peter,

steamer_ctn, on 15 July 2014 - 03:52 AM, said:

For further information on it, see here for further information.

Can we be more precise about the two terms

• Heat energy out of boiler
• Heat energy into boiler

because I find them a bit puzzling? Would I be right to say that:

• "Heat energy out of boiler" is that which passes through the walls of the steam tubes to heat the water and evaporate some of it to steeam
• "Heat energy into boiler" is that which is contained in the fuel, some of which passes through the walls of the steam tubes and some of which is contained in the exhaust gases and incompletely burnt fuel.

[copperpen]

Heat energy out of the boiler would consist of heat carried out by steam usage and heat lost through thermal radiation. Heat energy into the boiler is that portion of the exhaust gas heat transferred through the tubes and firebox surfaces, the unused portion being waste discharged to atmosphere via the exhaust stack.

[cjakeman]

copperpen, on 15 July 2014 - 10:45 AM, said:

Heat energy out of the boiler would consist of heat carried out by steam usage and heat lost through thermal radiation. Heat energy into the boiler is that portion of the exhaust gas heat transferred through the tubes and firebox surfaces, the unused portion being waste discharged to atmosphere via the exhaust stack.

That's even better (includes radiation and firebox surface). We are describing the heat transfer from the fuel to the steam/water mixture.

I think what is bothering me is those little words "out of" and "into" because I think of the boiler as the container for the steam/water rather than a set of fire-tubes.

Perhaps I'm being fussy :-)

[Genma Saotome]

How is heat into the boiler determined?

[steamer_ctn]

Hi Chris,

cjakeman, on 15 July 2014 - 10:19 AM, said:

Can we be more precise about the two terms

• Heat energy out of boiler
• Heat energy into boiler

I have tried to expand upon the information included in the documentation.

Cheers

[Genma Saotome]

What adjustments are performed to account for oil burning locomotives?

[copperpen]

I think that ORTSFuelCalorific covers all fuel types. I have used it to model the three main types of steam coal used in the UK with good results. Using ORTSFuelCalorific ( 13800btu/lb ) for instance is South Wales, Bedwas colliery steam coal. Plug in the value for wood and your wood-burning 4-4-0 will definitely not travel as far as a coal or coke burner using the same sized tender.

[cjakeman]

steamer_ctn, on 16 July 2014 - 01:08 AM, said:

I have tried to expand upon the information included in the documentation.

Much happier with that.

Thanks,

[Genma Saotome]

copperpen, on 16 July 2014 - 09:16 AM, said:

I think that ORTSFuelCalorific covers all fuel types.

I understand that. What I am concerned about is the parameters for coal burning are, essentially, irrelevant to an oil burner. The oil is heated so it flows as readily as water and is sprayed into the firebox where the droplets burn in the air. No fire mass, no grate, no grate area. All of the steam locomotives used along the Pacific Coast of the US (in the 20th century) were oil burners so it is not an insignificant number of locomotives that fall into this situation.

I'm also a bit concerned about this boiler efficiency curve -- I understand the importance of boiler efficiency -- that makes perfect sense -- but I do not understand the notion of it having a curve. All of the steam locomotive data that I have seen that provides data on boiler efficiency do so with a single number, sometimes over 100% but usually in the 95-98% range. Perhaps they are all oil burning, I don't recall now, but even if not, the question remains: Why a curve?