Hi, I'm working on an indirect liquid cooling system for my university's FSAE Electric team. The accumulator we are using consists of an array of 16 x 9 x 6 SAMSUNG INR18650-25R lithium-ion cells. However, I'm currently only using a 5 x 5 array to test the cooling system to make it easier.

As my supervisor informed me that the duration of my team's car's driving during tests and the competition will be about 22 minutes, I am making the SolidWorks flow simulation of my cooling system a time-dependent one, with a duration of 25 minutes (real time, not calculation time). However, I am unsure about what to set as the time step.

What I currently understand is that lithium-ion cells should be safe when discharging at a temperature in the range of 40°C-60°C. Since I am only concerned with maintaining the cells at this temperature range within the 25-minute duration, can I just select an arbitrary time step for my flow simulation?

(For reference, I set all 25 cells in the 5 x 5 array as surface heat sources each with a constant value of 7.2W, calculated by multiplying the square of the cell's max. discharge current of 20A by its internal resistance of 18miliOhms. I'm keeping the surface heat generation value constant as of now because I don't know how it will vary in actuality with respect to time, the car's acceleration, etc.)

Edu ​​​​​​​SOLIDWORKS ​​​​​​​Flow Simulation ​​​​​​​Formula SAE Electric ​​​​​​​