I like the basic concept, but I have a couple ideas for using the bags that may help with airflow. Either making an intake box or using a larger pre-made vent that can connect to flexible ducting. If you have an intake box then the bags could lie flat on top an opening sized smaller then the bags. The bigger the box, the more bags could be layed across the opening (supported with some sort of grid or screen.) cut a hole in the side to pull air through duct to fan and out exhaust. This would really help with resistance. spreading the intake over a larger area. But, then again, maybe it would pass through the thinner layer (as opposed to "stuffing in the duct" idea) too fast and reduce effectiveness? Just thinking out loud sorta... Hope that makes sense. I know pictures are best, but they only exist in my head at the moment. If I get around to trying I'll post pics.