A device that recovers heat from high-temperature
combustion products involves passing the combustion
gas between parallel plates, each of which is maintained
at 350K by water flow on the opposite surface.
The plate separation is 40 mm, and the gas flow is fully
developed. The gas may be assumed to have the properties
of atmospheric air, and its mean temperature and
velocity are 1000 K and 60 m/s, respectively.