Aluminum Cylinder in a Steam Engine?

[Philjoe5]

I have a block of some 7000 series aluminum that really wants to be the cylinder block for a steam engine I have in mind to build. However, at some point I might want to run this engine on steam since its piped into the model building that I show engines at in Kinzers, PA. I know this particular grade of alum has a coefficient of expansion twice that of steel. Is that going to get me into trouble? Do steamers use aluminum in cylinders? Advice always welcome,

Cheers,
Phil

 

[Maryak]

Phil,

All steamers I have had contact with use either cast iron or bronze for the steam cylinders of recips. Cast steel is used extensively in steam turbines. This is all 12"-1ft stuff but I think you would have trouble getting a good seal between the piston and cylinder using an ally cylinder and running on steam.

Hope this helps ??? ???

Best Regards
Bob

 

[Marinesteam]

While I have no direct experience using aluminum in a steam engine, I don't see why it wouldn't work if engineered properly.


If you use a material that has a similar coefficient of expansion for the piston you shouldn't have any problem with changing of size as it heats up.

My guess is that wear and rate of heat loss may be bigger factors, but not show stoppers.

Wear should not be an issue as the piston shouldn't run directly on the cylinder wall anyway. Either use PTFE or O-rings for the piston seal to reduce wear. The bore will need to be honed well. (read mirror-ish finish) if you use PTFE as the piston ring.

Tell us what you end up doing...

Ken

 

[lennardhme]

Ditto marinesteams advice, plus.....
You dont mention bore size or engine type [ oscillator ? ]
Will work perfectly well in a bore up to perhaps 15mm, after that I would be sleeving, but would need more info for a detailed answer.

 

[rodw]

I've seen a home made steam engine made using a two part ally housing (split horizontally) wrapped around a piece of stainless steel exhaust pipe. It was a pretty good sized horizontal engine that will be used to generate 12 volt off grid power. I don't think it has been run on steam yet as the alternator is still a work in progress.

 

[Philjoe5]

I actually did build this engine 4 years ago in two versions. It is based on a Ray HasBrouck design, 1.25" bore and oscillating rotary valve. The first version with the aluminum cylinder was never steamed but runs well enough on air. I never could decide what color to paint it :hDe:

the second version has a cast iron cylinder and steams quite nicely. It's shown here plumbed up to our club's steam boiler:

Someday, I'll put drain cocks in the aluminum version and try it on steam.

Phil