Free molecular heat transfer near a wall
N heat transfer between a gas and a wall, the heat flux can be determined by considering the transfer of heat at the wall through a layer so thin that the chances of intermolecular collisions can be disregarded Blodgett and Langmuir1 have analyzed heat transfer between two coaxial cylinders under the following conditions Heat from the inside cylinder at a temperature T is transferred by "free" molecules over a distance equal to the mean free path I, where the temperature is T fa (the difference T — Ta' is assumed to be the temperature drop) The heat is then transferred in accordance with the usual laws of heat conduction Without imposing limitations due to the possible effect of curvature of the cylinder, the investigators arrived at the following equation for the heat flux: