# Session 3 - Heating of a Living Room - Water flow

Hi, is it possible to adjust “Session 3 - Heating of a Living Room” so that you can set how much heat dissipation the radiator gives off? I do not just want to put it at 40°C.

Alternatively, that you can model a convector with copper pipes that connects to many tightly assembled fins (like a real convector)? Then you could control the water flow to the convector, and the flow temperature to the radiator, and then you could get the temperatur of the water return flow from the radiator, in this way you can calculate the heat dissipation. But this must also work with the natural convection solver that is available, because I have air that meets the hot fins in the convector.

Can you use conjugate heat solver when dealing with natural convection?

Thank You

Hi there!

Yes, you can use a Power source item to model the heat dissipation of the radiator. Check out the corresponding documentation page for reference:

Your second model is also possible, using a Conjugate Heat Transfer simulation. It will take into account the natural convection (buoyancy effect) and the conduction through the solid fins and pipes. Here are some tutorials on this solver:

Thank You, I will try that.
Now I’m trying to do the Session 3 from the above seminar, but my mesh looks not completed, and it only took 10 seconds to do the meshing, while the webinar talks about 10-12 minutes.
Can you help me?
The geometry looks fine, but the mesh doesnt look right, the radiator and sofa becomas 2D-face in the wall somehow.

I made a new own less advanced model in Onshape. I then get two solids, one which is the room itself, and one which is the radiator. I add “Absolute Power Source” and select the radiator solid. Then I make a mesh, that join my solids into one (1) mesh solid? And then my “Absolute Power Source” that I set disappears, and I can not add it after the mesh, because there is only one solid left after the mesh. What am I doing wrong? See new project below:

Hi again,

In order for the mesher to create a mesh with the two parts, you need to toggle on the option ‘Create multi region mesh’, in the mesh general settings panel.

Bear in mind that the best performance will be achieved by using the Standard mesh algorithm, thus this is what we always recommend.

Hi again, I coult not find “Create multi region mesh” when I have select standard mesh algorithm?
Anyway so I select “hex dominant parametric”, toggle on option “Create multi region mesh”. The mesh is fine with two separate parts, but when I simulate I get the following error message:

The following simulation run(s) failed:
Run 1
A multi-region mesh was assigned - this analysis-type requires a single-region mesh.

Hi again!

I checked the simulation project and couldn’t find the error. Did you delete this simulation? The geometry is also different right?

Anyway, the reason that you receive that last error is because you tried to perform a Convective Heat Transfer simulation with multiple bodies, which is wrong. If you need to take into account the solid body and conduction, the correct type is a Conjugate Heat Transfer.

Hi again, as I wrote before I made a less advanced room with Onshape, a room with a radiator (two solids).
It worked when I had convective heat transfer, and I put the radiator at 40C, but I tried to do what you said, put a absolut power to the radiator with advanced controls, and for that I used conjugate heat transfer. But it complains over no contacts. Se project where I switched to conjugate heat transfer:

I now made a convective heat transfer, and did a flow volume extraction (closed inner region). And then I could set boundary condition to the radiator with power. Now it worked.

Hi there, I am really glad it worked!