The aim of this project is to demonstrate the validity of SimScale’s CHTv2 solver by performing a conjugate heat transfer analysis of a battery pack by comparing the following parameter:
The simulation results of SimScale were compared to the results presented in [1]. Code Verification is also carried out by comparing the CHT v2 results to Fluent results.
Note
The validation case consists of two geometries Battery_Pack and Battery_Pack_v2. Both are essentially same however Battery_Pack_v2 is devoid of redundant face splits as compared to Battery_Pack.
The geometry can be seen below:
It represents a 1:1 model reverse-engineered from images in the publication. The battery pack consists of 32 (8×4) cell configuration.
The thermocouple location on the leeward side of the cells has been used for validating the CHT v2 solver:
The thermocouple readings from cells 3, 19 and 31 have been used for the comparison:
Tool Type: OpenFOAMⓇ
Analysis Type: Compressible, steady-state analysis with the Conjugate Heat Transfer v2 (CHT v2) solver.
Mesh and Element Types:
The Standard mesher algorithm with tetrahedral and hexahedral cells was used to generate the mesh. A mesh sensitivity analysis has been carried out to determine the dependence of the CHTv2 solver temperature predictions on the mesh, while using lead as the material of the cells:
Mesh Type | Number of cells/nodes | Temperature@L1-cell3 [\(°C\)] | Temperature@L1-cell19 \([°C]\) | Temperature@L1-cell31 \([°C]\) |
Mesh 1 | 3.6M cells, 1.1M nodes | 29.535 | 31.065 | 26.816 |
Mesh 2 | 11.2M cells, 3.5M nodes | 30.794 | 31.114 | 27.218 |
%TC deviation (Mesh 2 – Mesh 1) | 4.089 | 0.157 | 1.477 |
Maximum temperature deviation of 1.2 \(°C\) (~4.1%) between Mesh 1 and Mesh 2, was observed at leeward side of cell 3. In the following figure the percentage of temperature deviation in degrees Celsius (% TC) at measurement location L1 is displayed for three different mesh configurations as well:
In order to estimate the physical properties of the cells, a material sensitivity study has also been carried out, using three different materials:
Comparing L1 temperatures for the three materials, according to the diagrams below, aluminium cells show the closest match:
Hence, based on the material and mesh sensitivity analyses, aluminum cells and “Mesh 2” have been used for the final validation.
Fluid Material:
Solid Materials:
Boundary Conditions:
Convergence below 1e-3 has been achieved. Calculated physical quantities such as inlet pressure, outlet velocity, and cell average temperatures have also been allowed to converge to stable values:
The final temperature values are displayed in the following table:
Cell No. | TC@m2-SimScale-Aluminium \([°C]\) | Experiment \([°C]\) | CFD_fluent \([°C]\) |
3 | 28.54 | 29.42 | 29.92 |
19 | 28.49 | 29.01 | 28.52 |
31 | 27.22 | 30.99 | 27.78 |
Comparing CHTv2 solver predictions to thermocouple readings@L1, temperature deviations of:
The temperature deviations predicted from the CHTv2 solver are in good comparison with ANSYS Fluent. SimScale under predicts the temperature for all cells tested, however it is still close to the other results.
To have a more analytical look at the deviation between the experimental data and the results for the two software, you can also check the following graph:
The source of these deviations could be that:
In the following image, the temperature distribution across the flow domain indicates the heat transfer from cells to the air inside the battery pack. The cutting plane displayed is normal to the z axis:
Note
If you still encounter problems validating you simulation, then please post the issue on our forum or contact us.
Last updated: May 25th, 2021
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Validation case: Conjugate Heat Transfer in a Battery Packpart of: Validation case: Conjugate Heat Transfer in a Battery Pack