The study aims at clarifying the local heat and mass transfer in the desiccant rotor, and at obtaining the design aspects of high efficient desiccant rotor and operation method. In the paper, theoretical analysis is performed for rotary dehumidifier. Both surface diffusion and mass transfer coefficient are considered in the model. It is examined that the results of calculation agree well with the experimental data. The local temperature, humidity and the amount of adsorbed water vapor are calculated. It is clarified that temperature and humidity of air in the rotor change clockwise between each inlet air condition on the psychrometric chart. The outlet temperature and humidity distribution of the rotor is clarified in the system showing the optimum rotor speed. Furthermore, it is clarified that local desorption rate is higher than adsorption rate. It is attributed to the increase of mass transfer coefficient and surface diffusivity of the rotor during desorption process. And, it is clarified that the influence of surface diffusion on amount of adsorbed water vapor is much larger than that of mass transfer coefficient.
