The International Steam Pages

Proposals for a Heat Accumulator Fireless Steam Engine

Dominik (from Germany) has emailed me these ideas. If you want to get in touch to discuss them, please email me as below.

Heat Accumulator Fireless Steam Engine:

It was also one of my ideas in my early youth to bring back steam locomotives...Some components like LiNO3 can store enough energy to run an average shunting locomotive a whole day long (forty tons of it would be sufficient for about 800 kWh effective work). It is a big advantage of fireless locomotives that they can be used inside buildings or explosion protected areas. Shunting is also very inefficient for diesel engines which idle most of the time.

The use of such a locomotive is only useful if steam is available, in fact, so with a lower the melting temperature of the accumulator component, so more steam sources can be used and so the cheaper the heat will be. Only if the heat transfer can be realised by condensing steam inside the locomotive and drain back condensed water, a simple and effective way of recharging can be realised. The upper temperature limit will be given by the supercritical temperature of about 374C, but if the boiler pressure should be kept inside useful limits, about 200C would be suitable (keeping a boiler pressure of about 20 bar). The overall efficiency of such a steam locomotive is not independent of the steam source. One useful source could be saturated steam of about 20 bar, which could be taken out of a steam turbine process between the high pressure turbine and the intermediate superheater. The steam would have done some work in the turbine before it is used for recharging, this will be more efficient than using steam from the boiler directly.

The locomotive design can be very simple, the boiler will be just a big isolated cylinder, containing the water and the heat accumulators. The heat accumulators can be made of thin metal plates, since the pressure inside them is equal to the boiler pressure. Condensing sounds too sophisticated for shunting locomotives, but it would allow operations inside buildings and keeping a closed water cycle for the steam process. Due to the low average power output, it will be easy to realised, if condensed water is used as a heat sink during peak power output. It is not useful to pump back the condensed water into the boiler, because reheating would need to much energy.

Click here to return to the modern steam locomotive developments page.

Rob Dickinson