Solution of the linearized problem of heat and gas mass transfer in the gap between two cylindrical surfaces under a longitudinal temperature gradient

A method is proposed for computing heat and mass fluxes for rarefied gas flow in a duct between two eccentric cylinders. A constant temperature gradient is maintained in the duct. The kinetics of the process is described by the Williams kinetic equation, and the boundary condition on the duct wall is specified using the diffuse reflection model. The deviation of the gas state from equilibrium is assumed to be small. Heat flux profiles in the duct are constructed. The heat and mass fluxes over the duct cross section are found. The resulting expressions are analyzed in the transition to the free-molecular and hydrodynamic regimes.