Help with project design, thermal properties

[mendozer]

I'm trying to make a pizza oven, but rather than brick or refractory, steel. I want to use a hemisphere and have it fed by pellets. I've been told by people on wood oven forums that I won't get the heat needed.

I'm wanting 900 F at the hearth of the oven, using pellets for heat (roughly 8000 BTU/lb)

What I can't find anywhere online is scientific proof that it will or won't work. I'm looking to make a dome of 30" or maybe 36" inside diameters. There will be one chimney for air flow.

 

[Simon Bridge]

You won't get proof.
I don't see any reason you cannot get the required temperature ... it's a matter of getting enough fuel to burn.
It may be that they don't think your materials will give you enough refactory cooking. You have looked up the basics right?
http://site.outdora.com/blog/basic-anatomy-pizza-oven-3982.html

 

[mendozer]

I'm basing my plan off of the Uuni and the Roccbox, both metal ovens. Uuni is a double walled stainless, Roccbox has some form of insulation between two metal layers. carbon steel has a thermal conductivity (k) of 54 at 25 celsius. Dense brick is 1.6, Stainless is 16. Basing it off this, I imagine that the steel would heald up rather quickly but not retain it as well as brick. However, if I have a gravity fed pellet hopper, it just feeds itself.

What I can't figure out is if it'll get that hot and what kind of volume of pellet burning if needed to maintain 900 (or if it'll pass 900 and get too hot)

 

[Simon Bridge]

You'll have to experiment.

 

[billy_joule]

What I can't figure out is if it'll get that hot and what kind of volume of pellet burning if needed to maintain 900 (or if it'll pass 900 and get too hot)

You can calculate the heat (in watts) lost through the steel dome when the inner surface is at 900. Many heat transfer textbooks will have a worked example where heat loss through a single pane window is compared with a double glazed window. The difference is dramatic and is analogous to your single walled design compared to the double walled commercial units you've mentioned. I'd guess you'd need at least triple the fuel mass flow rate to maintain the same temp. And the dome Will be dangerously hot.