1067Re: [pop-pop-steamboats] Our new members
- Nov 30, 2007
----- Original Message -----
From: "Donald Qualls" <silent1@...>
> This makes perfect sense, then;
However few owners give any thought to air: it just happens, or not.
With the diaphragm type motor, it would be hard to exclude all air as it
will lurk in the recesses when the motor is first filled.
However with the coil type it would be difficult to include any, but some
will come out of solution as soon as the water is heated.
It is possible that there are several different types of successful
configuration - long tubes, short tubes, immersed tubes, inboard tubes etc
and I can't get my head round it all. But as you say, folk who have made
transparent motors have found them instructive.
A Stirling engine:
- compresses a load of gas (usually air),
- heats it up while compacted
- lets it expand (providing a power stroke)
- cools it down while expanded.
A Rankine engine:
- boils a load of liquid (usually water),
- lets the steam expand (providing a power stroke)
- condenses it back into water
- pumps it back into the boiler.
Either can be used either as a motor or be motor-driven to act as a heat
pump shifting heat from a colder zone to a warmer one. For example a
Rankine engine can be made either as a steam power plant or as a
There have been a lot more Rankine engines built than Stirling engines
because it's a heck of a lot easier to pump liquid than to compress gas,
and because a lump of steam holds a lot more heat than a lump of air at the
There: the fundamentals of Mechanical Engineering on a postcard!
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