Insulating from heat transfer

Hello,

I am assisting in the design of some heating heads.

We are using a 2000W rod type heating element, and

want to apply heat through an aluminum plate

(1/4" thk., touching the heating core and about 1/2 to 1" in height, x 8" lg.).

(Temp. range about 400 to 700 deg. F.)

I need to isolate the plate, to insulate the rest of the

head ass'y. from the heating element. (So the rest of the

heating head doesn't act as a heat-sink, drawing heat away

from the plate...). The project Eng. wants to use a

Ceramic/Mica composite, for one because it is 'machinable'.

(The product spec says the thermal condutivity of this

ceramic is about 2.4 BTU @ 75deg. , but not being an

engineer experienced with thermal condutivity, the numbers

don't tell me much...)

The debate is whether an air pocket would do a better job

of insulating.


What is your opinion / advice ?

We need a good insulating material, which would be reasonably easy to machine (preferably without diamond tooling), that is easy to obtain and not overly expensive.

Is simply using an air pocket a better choice than any
ceramic composite? How much of an air space do you think would be necessary to minimize heat transfer?

Thank you very much - in advance - for your kind reply.

 

[prodeng]

While there are undoubtedly those with more time and experience to deal with an issue like this, one big advantage of the ceramic over an air space in an application like this is the reduction of radiant heat. At those temperature ranges, radiant heat is at least as important as conductive heat. The ceramic thermal conductivity listed depends on the thickness (cross-section) for effectiveness (typically thermal conductivity is BTU/(h*ft*F) where 1 hour is assumed, and you gave 75 deg. F) but comparing it so some other solids, it beats asbestos which was used as an insulator for years in high heat applications. Hope this helps some. [sig][/sig]

 

Thanks Prodeng.

we are going with the ceramic, but haven't implemented
the new design yet...


!!!! PLEASE consider this topic closed !!!!

 

We interested in knowing is there any machinable effective insulating material which could take sufficient amount of tensile and shear loads.