We have studied heat and mass transfer in a zeolite bed during water desorption. For this purpose, a mathematical model based on scale changing has been established. We have tested the local thermal equilibrium assumption in a two-dimensional flow.The problem is numerically resolved using a finite volume method. The numerical simulation gives the time and space evolution of temperature and moisture content. The influence of different effects (essentially the effective conductivity of the solid and the reactor geometry) on the total mass desorbed are examined.