Examine how the existing dryer in your home is vented. The flexible or rigid duct exits the appliance at the back and travels a short distance to the outside of the home. There are very few turns, usually just two, and the duct is kept as straight as possible. Never coil up excess flexible piping.
Install the new dryer, other both, if you are installing two at a time, against an external wall. The ductwork for both dryers should be kept completely separate. The 4-inch diameter of standard clothes dryers is designed to handle the flow of air for one appliance only. It's fine to run the ducts parallel.
Attach the dryer end of each duct to the exhaust connection on the back of the appliance. A screwdriver-tightened clamp is often used to attach the ends of flexible pipe or the sections of rigid pipe. Assemble the duct in pieces using as few 90-degree elbow sections as possible to reach the exit point in the exterior wall. Use duct tape to get an airtight seal.
Connect the end of the duct to the exhaust hood. The hole for the exhaust hood must be drilled through the side of the house during the installation process. Two holes are necessary when venting a pair of dryers. The appliances cannot share an exhaust hood. Never have a dryer vent into a crawlspace, attic, basement or any other type piping.