buy some kd (knock down) rigid duct from home depot, and remember every 90 degree elbow is like running 30 feet of straight duct. more 90s, more static pressure build up, fan has to work harder. would not recommend dryer vent at all. put damper (or fan controller)in supply so u can regulate negative pressure in room. if using co2 put backdraft damper in supply so no air escape through supply and electric damper on exhaust so it will open and shut when fan comes on and off. just my 2 cents, but don't trust me i have only been doing hvac for 11 years.