Problem with max temperature of analyzed volume

[imestre]

Hi, I´m doing a transient thermal post-processing analysis in a volume of water cooled by peltier modules in indirect contact with water (using aluminium cylinders to improve the thermal transfer). The system is inside a box of certain thermal insulator material and I´m studying the max and average temperatures of water (consideraded as solid, despising movement) after 20 minutes for different insulator thicknesses.
The problem occuers when solving the model with an insulator thickness of 106 mm, the max temperatura reached is 28.34 °C. But, when solve for an insulator thickness of 70 mm, 50 mm and 30 mm, the max temperatura in the water volume is 20.28 °C, 20.88 °C and 21.66 °C, respectively. There is clearly an error because that max temperature should be below 20 °C.
Can anyone please help me finding the problem with mesh (I guess that the problem is there, but not really sure cause all models have same parameters).
link of project with insulator thickness of 106 mm: SimScale
link of project with insulator thickness of 70 mm: SimScale
link of project with insulator thickness of 50 mm: SimScale

Thanks and regards to all!

[Ricardopg]

Hi!

Thanks for the links & detailed explanation.

Firstly, for the simulation with 106 mm of thickness, it looks like a single cell in the water domain developed high temperatures (likely due to insufficient discretization). You can try to increase the mesh density further and run the simulation again:

On a side note, I’d recommend that you use the average values in the water domain with the bulk calculator - they should be more representative. For example: 6.423 ºC in the image above (106 mm) versus 6.507 ºC for the simulation with 70 mm insulation:

Cheers