240cfm fan... inline centrifugal fan....... or a 'booster fan*' (*max speed when installed in a closed system with a main fan pushing it)
Go big on fans, always easy to put on a speed controller, not so easy to force more airflow than design allows.....
My early grow room used a 4" exhaust fan system to go outside, matches bathroom/laundry venting.... later did portable a/c vented out the window.... (warning, SMELL, cant filter this way)
You gotta vent somewhere, gotta have the 'fresh' air be cooler than the temps, and after a few hrs of lights, that may be tough... I would go with a window A/C unit in the room, a 400cfm 6" fan on the lights, pullin thru a filter....