Air Flow Calculation

This sounds like a duplicate post--did you get no response to your first post?

I can't help you very much--I'd start looking for fans the can develop 9500 CFM and seeing how big they are--you want to get air flow across the entire cross section of the load bank to avoid hot spots that might exceed 50 degrees C (possibly hot enough to burn out the resistive wire, either very quickly or over time).

You also need to figure out the velocity of air moving through the cross section of the fan, and the pressure drop through the load bank based on its shape and the construction. (Then, of course, the fan you need must move 9500 CFM at that pressure drop.)

What is a 500 Ekw load bank used for (what will yours be used for)? Will it be needed for continuous duty or intermittent duty--how intermittent?

We once had to build a "load bank" like that to calibrate and test circuit breakers in a mining environment. We didn't provide forced air cooling as the duty was very intermittent--sometimes we did have to manually trip the circuit breaker if it didn't trip quickly enough and we thought the resistive wire was glowing too brightly. ;-)

One reason for asking the purpose of the load bank--well, I guess my point is, have you asked the manufacturer of the load bank if they can either provide or recommend an appropriate fan. I would think they've had other customers with similar needs, and they know the most about their load bank, and what the pressure drop across it might be....

Hmm, I probably should have just said "contact the manufacturer".

You disappointed me! I was sure you were going to throw VFD in there somewhere