 ## General Mechanical

#### How to load heat transfer capacity from an external table with dependent point?

• Tim Fricke
Subscriber

Hello there,

I have the following problem.
In my simulation I have to apply a heat transfer capacity. This has been determined in a real test and depends on the temperature at two points on the model.
The following graph shows the measured data. My question now is how can I load the measured values into Ansys?

And when this is done, how can I assign the heat transfer capacity so that the correct value is retrieved for the respective temperature?

Best regards,

Tim

• Dave Looman
Ansys Employee

Will you be solving for the temperature of both the heat source and the heat sink?  Typical thermal models would be 3D representations of the sink and source and the heat would be in the form of a flux, W/M^2, not just Watts.  What's a physical description of what you are modeling?  There won't be a simple way to load the temp-dependent heat source into Ansys.  If the sink or source temperature was constant a temperature dependent convection could be defined between the two bodies.

• Tim Fricke
Subscriber

Hi Dave,

thanks for the answer. I would like to simulate the time course of a cooling process.

A temperature load is applied to surface B. The temperature in the center of the surface should also be the source temperature.
The heat sink temperature is constant as you have already assumed.

On the surface A the body is cooled and the temperature is extracted. For this I wanted to create a heat flow with the values from the graph.

The heat flow is actually the output of a heat pipe and the values were determined experimentally. • Dave Looman
Ansys Employee

You could specify a negative heat flow on surface A and a temperature at the center of surface B.  If the temperature is specified at the center of surface B that will limit the cooling.  Specify a heat flow as a function of the model temperature may be possible, but its not a standard capability of the gui.

• Tim Fricke
Subscriber

Ok, I almost thought that it will not be so easy :/

Unfortunately, I still have to simulate it anyway. My approach would be to add an APDL command to the loads. Then I read in the values and pass on the corresponding heat flow.
Would this be possible with this process ? I just want to be sure before I spend the time to learn the relevant apdl language.

• Dave Looman
Ansys Employee

Yes, it's possible with APDL commands.  The general technique is to break the solution into many short time steps.  At the end of each time step you can query the model temperatures and apply a heat flux or flow based on a formula or table using a Commands Object that is to be executed every step (assuming you are in Workbench.)  For example:

...

SOLVE

temp_1 = temp(node(x,y,z))

temp_2=temp(node(x,y,z))

sf,named_selection,hflux,100*(temp_2 - temp_1) 