Dryer vent backdraft damper
I would run straight smooth metal pipe, with 45* elbows (unless close to the max. on elbow deductions) right through the crawl door/plywood. Oversize the hole, add metal tin pieces (overlapping at center circle cutout), use Type A hood with aluminum foil tape at all joints, including each individual elbow. If a gas exhaust also, follow codes sited- 3' from openings, etc. Don't forget to use stainless steel flex hoses on the water supply to the clothes washer (no burst).
Be safe, Gary
Clothes taking longer to dry?
Clean the dryer screen in HOT water if using fabric softener sheets.
They leave a residue that impedes air-flow, costing you money.
Clean the ducting in the last six months? 17,000 dryer fires annually!