Battery Module Heat Rejection Testing

This set of testing was done to determine how much heat we can remove from the battery module with the 1 Noctua fan NF-F12 iPPC 3000. Remember this is the prototype module with consistent 20.2mm spacing between cells.

The thermistors were placed in the middle of the input and output air stream. The fan is located on the output side of the module, pulling air through the cells. The air flow was measured in the black 3D printed tubes.

Airflow was measured at the input at an average of 3.3m/s.
Airflow at the output was measured at 9.2 m/s.
This discrepancy in the air speed measurement is surprising. The air speed was measured at the start of the test and was not remeasured when the cells were hotter.
The air speed directly determines the air flow, which determines the amount of heat removed from the module, so getting this measurement right is crucial. I cannot make sense of these measurements, as the air flow in and out should be the same. Both the input and output tubes are the same size, and I did not notice any gaps in the masking tape sealing.

The amount of removed from the module was determined using the airflow, the specific heat capacity of the air, and the temperature between the input and output air streams.

As can be seen from the graph, the relationship between temperature difference and amount of heat removed was roughly linear, as expected from the convective heat transfer equation: Q_c = h_cA(T₂-T₁).

Note: Calculated using the 9.2m/s air speed.