The model of a steady-state smoke layer, including wall heat transfer, initially developed by Alpert [1] is extended to the general non-Boussinesq framework in an inclined tunnel configuration. This model, which is based on the mass, momentum and convective heat conservation equations, provides the longifihtudinal evolution of the velocity \(U\) , the temperature \(T\) and thickness \(h\) of the layer through a system of differential equations. This system could be express as a function of the local Richardson number Ri - and the local Stanton number St. The main results address the influence of heat transfer on temperature, with a significant decrease in temperature as the Stanton number increases.