Expansive power of steam?

[applescotty]

I've heard of the expansive power of steam, and understand that utilizing it will make your engine more efficient. However, I don't understand what this expansive power really is. I've done some searches, and didn't find anywhere that explained it. What does the steam do that is different from compressed air?

Scott

 

[compound driver 2]

it expands in the cylinder, compressed air dosnt.

 

[Maryak]

Scott,

Welcome to the forum, attached PDF may help. ???

Sorry about the quality but its a pretty thick book and a pretty crappy scanner :

Regards
Bob

View attachment Expansion.pdf

 

[rawblacksmith]

for unloaded models, temps of compressed air don't drop after expansion as they do with steam.

 

[applescotty]

Thanks guys for the responses. Maryak, thanks for scanning those pages. Still trying to get my head wrapped around it. So, the heat of the steam has something to do with it, right?

Scott

 

[Maryak]

Scott,

Yes the heat of the steam has something to do with it. As the steam cools it loses pressure and temperature but gains in volume, i.e. it expands or gets bigger and during this process it can be made to do work.

Hope this helps
Regards
Bob