Dr. Physics to the rescue!
Yes, Heat rises. Physics 101.
Physics 401 Temperature in a closed system cannot exceed the input
temperature. And due to convection, conduction and radiation to the
atmosphere, it will be below the input temp. What's the input temp of an
oven element? No clue, never measured one. But you don't need to know
it. You just need to have an accurate thermostat that cycles it on and
off in response to the oven temp rise, which kitchen ovens have. Locate
the temp sensor at the critical point and the thermostat will respond
accordingly.
When a closed fluid system develops a wide temperature variation,
complex systems of convection currents are set up that tend to equalize
the temperatures. Also radiation and conduction will occur with
temperature differential. As long as the oven is not so stuffed with
stuff that these currents can't flow, you will be OK.
If you feel you need to control this behavior, or you need drying, you
can open the system to atmosphere on the top and bottom and use what you
learned in Physics 101 and control the rate of air exchange with
variable vent or chimney size. Heating power consumption will go up. The
temp sensor still needs to be located in the critical spot. And baking
time will probably increase.
The closed, vertical box maximizes the direct energy input from the
element in to the part. You are using all the natural forces to convey
the energy to the part.
Jon "Kilns R Us" Rush
"Landaiche Kenneth (NET-BBS/Petaluma)" wrote:
>
> But heat rises. Unless you add an air circulation system, the top will
> be much hotter than the bottom. With such a long aspect ratio, the heat
> distribution will be much more even with less vertical dimension, with a
> horizontal box.
>
> Ken
>
> -----Original Message-----
>
> You want a vertical
> box that is about the same dimensions in plan as the oven. In other
> words, build up vertically from an oven sized box. The heating elements
> in a an oven are shaped to distribute heat evenly over that plan area.
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