Which pollute more -- steam or diesel?

Discussion in 'Getting Started' started by RobertInOntario, Feb 28, 2007.

  1. Travellar

    Travellar Member

    Under a 'standard' steam design, 80-120 MPH, for the same reason as fuel burning steam locos. There is a practicle limit to how much speed you can get by pushing back and forth on a large piece of iron or steel.

    Using a steam turbine, and possibly electricly coupled, 80-120 MPH, unless you want to lay specialized high speed track. Then you can go as fast as you want. Which still doesn't make a lot of sence, because if you're laying specialized track, you may as well just go electric and be REALLY green.

    I forgot to mention, the degree of efficiency you can get out of different set-ups, (assuming you also meet power/unit requirements) quickly becomes more of an engineering project than anything. Both steam and diesel are heat engines, relying on the application of heat to cause expansion or pressure, which can then be used as a motive force.

    In theory, steam can be more efficient, as that pressure is maintained, and used in the pistons only when ready for it, and can be re-used in a mallet design. In practice though, diesel usually wins out because pretty much all of the heat is used to expand the gasses in the cylinder and gain useful work. Steams radiate a tremendous amount of heat from thier boilers, and lose a lot of heat in the exhaust gasses.

    Back to a strictly engineering problem, One could build a steam engine with considerable insulation around the boiler, superheating, and use the last run of the exhaust gasses to preheat the water fed into the boiler. Then use this in a mainline application, where the job is to move at X speed from point A to point B, so the engine can be very well designed for that one speed application. In the end though, it isn't as practicle as building diesels which can also be purpose built for the same kind of efficiency, and still maintain more flexibility in roles.
  2. tverskaya

    tverskaya Member

    But...when civilization collapses then steam locomotives will be the last to come to a halt!
  3. RailRon

    RailRon Active Member

    Only now I stumbled over this very interesting thread. Here is some update about modern steam:

    Triplex mentioned the Swiss firm which builds modern steam engines. The DLM (Dampf (= steam) Locomotive and Machine works) is a spin-off of the former SLM and exclusively produces steam engines since 2000! They also have an English website (click on 'Welcome') where you can see what is possible, using today's technology in the construction of new steam locomotives (and ship steam engines). They also do revisions of older steam power.

    Environment protection is a main issue, and the efficiency of their newly built steam locos beats the diesel locos on the same mountain rack lines anytime. They use light diesel oil, computer controlled firing, extensive thermal insulation and modern, lightweight materials.

    Their newest project is a steam powered commuter train (near my home BTW) between Olten (a major railroad knot in the center of Switzerland) and Sissach through a lovely landscape. The idea is to attract tourists and steam fans as well as the daily commuters of the whole region.
    Here is a leaflet in English which explains the whole idea.

    The picture [drawing (c) by DLM] shows the proposed shuttle steam train with a one-man 2-8-2T engine. She pulls four cars with panoramic glazing. The 'end' of the train is furnished with a cab from where the engine can be run by remote control! So a perfect push-pull service without need to turn the engine is possible.

    You can bet that I am very anxious to see if this project really will be realized. Of course I hope so. Imagine - to hear the chuff and the whistle of a steam engine every day, and this in the year 2009 (hopefully)!


    Attached Files:

  4. Triplex

    Triplex Active Member

    You know, that was done back in the "steam era" in Britain... the Great Western Railway, I think?
  5. RailRon

    RailRon Active Member

    Also the German 'Reichsbahn' made such experiments even before WW II. But the difference is that at this time you still had a complete crew on the locomotive plus a second engineer in the cab at the other end of the train. They were connected by telephone. At least in Germany the experiments were ended because they realized that the reaction in an emergency case would be too slow.

    In this modern project there really is only one single engineer on the train who runs the engine by true remote control.


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