A little slo' on the intro' from GR, MI

[vargthewanderer]

Hello all!

I've been interested in steam engines since I was little kid, though I seem to be attracted to them for useful purposes like generating power or pumping water, powering vehicles, etc. I'm currently studying mechanical engineering at Calvin College in Grand Rapids, so my studies have rekindled my desire to build and design one/few/many.

I've toyed with the idea of converting a small to medium sized gas engine to steam by replacing the top piston rings with packings and building a separate valve system to be driven off the cam gear instead of using the cam/lobe system. I *think* that should make it easier to play with the valve timing, but what do I know?

Any who, I just finished poking around the forum some more, reading some steam tables scribbling some numbers on my notebook, and I came up with 755 gal/hr of 120psi steam to run a 2L engine at 100RPM. Is this really accurate, or am I doing something wrong? Did locomotives really carry around olympic swimming pools of water to run for an hour?

More over, is this the real reason everyone here builds tiny steam engines?

It's a great forum you all have going here. I'm looking forward to picking brains and watching projects grow.

-Clark

 

[Tin Falcon]

welcome to the forum

More over, is this the real reason everyone here builds tiny steam engines?

They are fun to build.
Tradition: model engineering books and magazines have been around for over 100 years.
Many if not most home hobby shops and machines are small. therefore capable of machining small engines.
The law of scaling: If one builds a 1/10th scale model of an engine that weighs several thousand pounds it only takes a few pounds of material and uses 1/1000th of the steam.
models are much cheaper to build easier to transport , store display maintain etc.

Model building teaches the same mechanical principles as the full size engines .as well as teaching and honing machining skills.
Tin

 

[Cogsy]

Any who, I just finished poking around the forum some more, reading some steam tables scribbling some numbers on my notebook, and I came up with 755 gal/hr of 120psi steam to run a 2L engine at 100RPM. Is this really accurate, or am I doing something wrong? Did locomotives really carry around olympic swimming pools of water to run for an hour?

Welcome to the forum Clark.

I know zero about steam engines, but based on what I can remember from school, I'm guessing the figures you're quoting relate to the quantity of steam not water. IIRC steam expands by 1600% by volume from water, so 755 gal of steam would be 755/1600 = 0.472 gal of water. I speak metric so 1 millilitre of water would generate 1.6 litres (1600ml) of steam.

I could be way off base though. As steam is compressible, the 120 psi could affect the calculations quite a bit, but it will still be less than 755 gal of water.

Have fun finding out!