An analytic study for vapor absorption into LiBr-$H_2O$ solution film flowing over horizontal tubes is performed. This study applies to absorption process occuring in the absorber of the absorption refrigeration system. The momentum, energy and diffusion equations which are parabolized by the boundary layer approximation are solved simultaneously to consider the effect of the variation of mass flow rate by the film absorption. The results for velocity, temperature and concentration fields, as well as heat flux and mass flux at the free surface are presented. Also, the effects of inlet flow rate, inlet temperature and inlet concentration are investigated.
