Learning Forum

[Alessandro Bugin]

Hello gentlemen,

I’m new in this forum and I’d like to discuss with you on a topic that I’m working through.

I have to simulate a resin jig that it’s put in a oven for 2 hours with a temperature cicle (maximum 80°C).

I want to find the temperature of the jig during and at the end of the heating.

 

I created a Transient Thermal simulation, I imported the jig and an air cube (1m3, I removed the volume of the jig); I set the material, resin and air, with density, isotropic thermal conductivity and specific heat parameters.

 

 

I set the temperature like a cicle on the 6 outer surfaces of the air cube and I set the conductivity between the jig and the air. Please think that I have an industrial oven (like 16m3) that works with hot air.

 

I solved the system to find the temperature of the jig, but after 2 hours the jig is at 24°C.

 

Are there any mistakes? Should I have to modify anythings?

 

Let me know if I was clear. I remain avaiable for any clarification.

[peteroznewman]

The mistake is that air in Transient Thermal is fixed in space and heat can only conduct through the air. As you may know, air is a very good insulator if it can't move, but a very poor insulator if it can move. To model the movement of air in an oven, use Fluent.

If you don't want to use Fluent, you can have a model in Transient Thermal of just the jig but no air. Put Convection boundary conditions on all faces of the jig and use the Tabular Data to type in the air temperature vs time profile for the heating cycle. Note that the Film Coefficient should be slightly different on faces of the jig that are vertical vs horizontal for the case where the oven does not have a fan to move the air around.