Carriage Steam Heating

Aim - this section describes the principles behind steam heating of carriages.

Introduction

In the early days of steam, passenger carriages were heated by fire burnt in stoves within the carriage, but this type of heating proved to be dangerous, as on a number of occasions the carriages actually caught fire and burnt.

A number of alternative heating systems were adopted as a safer replacement.

The Open Rails Model is based upon a direct steam model, ie one that has steam pipes installed in each carriage, and pumps steam into each car to raise the internal temperature in each car.

The heat model in each car is represented by Figure below. The key parameters influencing the operation of the model are the values of tc, to, tp which represent the temperature within the carriage, ambient temperature outside the carriage, and the temperature of the steam pipe due to steam passing through it.

As shown in the figure the heat model has a number of different elements as follows:

  • Internal heat mass - the air mass in the carriage (represented by cloud) is heated to temperature that is comfortable to the passengers. The energy required to maintain the temperature will be determined the volume of the air in the carriage.
  • Heat Loss - Transmission - over time heat will be lost through the walls, roof, and floors of the carriage (represented by outgoing orange arrows), this heat loss will reduce the temperature of the internal air mass.
  • Heat Loss - Infiltration - also over time as carriage doors are opened and closed at station stops, some cooler air will enter the carriage (represented by ingoing blue arrows), and reduce the temperature of the internal air mass.
  • Steam Heating - to offset the above heat losses, steam was piped through each of the carriages (represented by circular red arrows). Depending upon the heat input from the steam pipe, the temperature would be balanced by offsetting the steam heating against the heat losses.

Steam Heating Model

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Implementation in Open Rails

For the time being steam heating is only available on steam locomotives.

To enable steam heating to work in open rails the following parameter needs to be included in the engine section of the steam locomotive ENG File:

MaxSteamHeatingPressure( x )
Where:
x = maximum steam pressure in the heating pipe - should not exceed 100psi

If the above parameter is fitted to the locomotive, then an extra line will appear in the extended HUD to show the temperature in the train, and steam heating pipe pressure, etc.

Steam heating will only work if passenger cars are attached to the locomotive.

Warning messages will be displayed if the temperature inside the carriage goes outside of the limits of 10 - 15.5oC.

The player can control the train temperature by using the following controls:
Alt-U - increase steam pipe pressure (and hence train temperature)
Alt-D - decrease steam pipe pressure (and hence train temperature)

It should be noted that the impact of steam heating will vary depending upon the season, length of train, etc.

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Useful Links

The Steam Heating of Railway Carriages by Frank Marillier

Section #26 - Car heating (from International Library of Technology)

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