Several-temperature systems: extended irreversible thermodynamics and thermal wavefront propagation

We develop an extension of local-equilibrium thermodynamics for systems wit h components at different temperatures. The description includes heat condu ction, diffusion, a chemical reaction and heat losses. The ensuing equation s are applied to the problem of thermal wavefront propagation. There is sat isfactory agreement between the predicted and the experimental values for t he speed of combustion flames over cellulosic fuels. Heat losses cause a de crease of the front speed. This generalizes Zeldovich's result. For radiati ve losses, the effect can easily be about 15%. When the finite speed of the rmal signals is taken into account, an additional lowering of the thermal w avefront speed results.