I have an idea, but don't know if it's an good. Instead of blowing air horizontally like you do now, blow air from floor to ceiling. The cooler air is lower because of density and you blow that over the fans and up to the ceiling. Like this:

-----------------ceiling

[-------------] Miner
[-------------]

{^^^^^^^^} Fan blowing air up
|                  |
--------------------Floor

Probably a better recirculating setup?