US Patent 7931961 Composite exhaust flue

A composite exhaust flue which may be used to shield an area or object from convective, conductive, or radiated heat transfer from hot exhaust combustion gases is described. In certain embodiments, the composite exhaust flue may be used to protect structures from hot exhaust gases and particles such as those produced by cars, trucks, ships, boats, jets, rockets, as well as other vehicles with internal combustion engines, turbines, or rocket motors. In some embodiments, a composite exhaust flue may comprise a ceramic fiber reinforced ceramic composite high temperature face sheet positioned over an insulating layer and a structural support layer comprising a rigid, porous foam material.