The slip flow and heat transfer through a rarefied gas confined between concentric cylinders are investigated. The heat transfer and flow between a heated tungsten filament and a surrounded rarefied gas (N2) has been studied numerically; gas temperatures range from 300 K in the envelope region to 3000 K at the wire. Temperature, density and velocity fields are calculated. This work has been carried out using the CFD (Computational Fluid Dynamics) computer code Fluent (Fluent® 6.3.26). The LPBS method proposed in Fluent for implementing slip conditions is used. The influence of the mesh type on the solution has been examined by using the CFD code Fluent and the analytical solution.