In this page, air cooling design is discussed.
Inlet/Outlet Positioning
In this study, multiple configurations of inlet and outlet positions on 4x5 18650 modules were simulated for max temperature and temperature difference.
The study found that schemes 1, 2, 7, 15 had high relative final max temperatures while 3, 4, 12, 13 had low relative final max temperatures. Designs with poor performance had the inlet and outlet too close together causing a lack of airflow to most cells not in the flow path thus preventing sufficient convective heat transfer between the air and certain cells.
It is also interesting to note the differences in outlet airflow as this can be a large factor in determining the air velocity throughout the battery pack.
Schemes 13 and 24 were determined to be most optimal with good fluid flow and best performance overall. The study concluded that the longer the fluid flow path, the more uniform the temperature distribution of the battery pack. However, we may want to prioritize minimal max temperature over uniform temperatures due to the short length of time the battery will be used. In conclusion, it would likely be best to have the inlet and outlets be on opposite sides like in scheme 13 and 24 but not in-line. Having the openings offset lengthens the air travel path allowing more opportunity to dissipate heat.