Control Engineering

Peter Welander

The search for energy efficiency, part 1
February 12, 2008

Thinking about the conversation on hybrid car efficiency mentioned yesterday got me thinking about experiments with steam locomotives in the 1920's and 30's. (Stick with me here.) The thermal efficiency of a typical locomotive of that era was very low. I don't have exact figures, but I suspect reaching 20% would have been exceptional. Given the small boilers and non-condensing engines, the amount of unrecovered heat would be horrendous.

Railroad men at the time were concerned about fuel economy, and they wanted to test concepts that are part of standard steam plant designs to this day. (This web site gives some interesting examples.) The concept of gaining efficiency through higher boiler pressures, compound engines, and more efficient valve gear did, in fact, cut coal consumption, in some cases dramatically. The experiments certainly made for some interesting looking motive power.

The downside was maintenance. A steam locomotive was a maintenance intensive machine under the best circumstances, but adding more cylinders, booster engines, higher pressure steam handling, made it a nightmare. Savings from reduced fuel costs evaporated in the engine house and depression-era cash flow put an end to the experiments. Had the cost of coal doubled, the situation might have changed dramatically and changed people's thinking. More to come.

Posted by Peter Welander on February 12, 2008 | Comments (0)