Hello All,
I am hoping you can help me with some heat transfer modelling I am trying to do. I am new to FEA and have no background in it unfortunately, but have spent the last two days trying to learn and do some modelling. What I am trying to do is model the temperature of a solar cell under concentrated light depending what size heatsink is used. I drew up a model in FreeCAD which consists of a very thin solar cell (0.017 x 10 x10 mm ), a 0.125mm thick solder and then a 50x50mm copper plate. I have successfully got this into Prepomax and meshed it etc…
I then added the material properties to each layer and set up contact pairs. I started with a surface flux of 136.6 mW/mm2 (1000X concentration) and set the copper plate as a convective film. However, when running a simulation it doesn’t appear to take into account the copper and solder (these stay at 25 C, whilst the solar cell gets hot). I can’t figure out how to model the heat transfer between each layer.
I have attached an image of the results in the hope someone can have a look and help me out.
Thank you
Dave
Try using tie constraint instead of contact. If it doesn’t help then there might be a mistake in your setup and it would be best if you could share the .pmx file.
Good morning, thank you for your quick response. I did try to upload the .pmx file but it sais that “new users cannot upload a file”
You could share it using some hosting website like Google Drive, Dropbox or WeTransfer. Just paste the link here.
Ahh yes, good idea. link attached 
The distribution will be much better if you replace contact with tie constraints:
But you may still have to refine the mesh in the thickness direction to obtain correct results. Add convective film to other faces as well if they are subjected to heat transfer with air. And make sure that the values (like heat flux) make sense. You may want to use transient analysis instead of steady-state to see how it heats up during some time. Otherwise, you only see the end result when the temperatures don’t change significantly in time anymore.
That looks great! Would you mind sending me the file with the tie constraints included please as I am a bit confused when trying to add them myself.
I’ll then refine the meshes and ensure the heat fluxes make sense.
Thank you
Here’s a version with tie constraints (too big to share directly here): WeTransfer - Send Large Files & Share Photos Online - Up to 2GB Free
Amazing, thank you! Very much appreciate your help
