Due to the internal resistance of battery cells, they produce heat when a current is applied to them. We must dissipate this heat somewhere to stop the cells from heating up.
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We measured the airflow of our Noctua IPPC fan when pulling air through 1 or our prototype modules (see this page). We will be contacting Noctua to obtain a more accurate P-Q curve for their fan.
| Condition | Airflow (m3/h) | Airflow (CFM) | Static Pressure (from Cooling Technique Testing) | Static Pressure (from Noctua P-Q Curve) |
|---|---|---|---|---|
| Just fan duct | 26.97 | 15.87 | 5.55 | |
| 1 Module and fan duct | 15.52 | 9.13 | 5.6 |
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Anything in the airflow path is essentially an impedance to said airflow, and can be thought of as a resistor in an electrical circuit, with the current being the airflow.
Have a look at the airflow page: http://www.arx-group.com/airflow1.html for an explanation on system impedance, which is sort of what I was trying to calculate here.
Required Airflow
Now we need to figure out how much air we need to move through the battery box. We will be using this page as a reference for these calculations: http://www.arx-group.com/airflow.html
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| Variable | Description | Value (Units) |
|---|---|---|
| H | Least amount of heat removed | (W) |
| Cp | Specific heat capacity of the air | 1005 (J/Kg℃) |
| M | Mass of the air | (Kg) |
| ∆T | Temperature difference | Tc - Tamb (℃) |
M = Q x ρ
| Variable | Description | Value |
|---|---|---|
| M | Mass of the air | |
| Q | Flow rate of the air | |
| ρ | Density of the air | ρ = 1.18 Kg/m3 |
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