The mechanisms of through flow drying were investigated experimentally and theoretically. Part I of this paper deals with heat and mass transfer during the constant drying period. The experimental data were obtained by measuring the rate of evaporation of water into a stream of air from wetted granules and packings during the constant drying rate period. The drying rates of a single layer of wetted porcelain particles packed between two layers of dry glass spheres were measured and those of random packed beds also were obtained. From a comparison of the transfer data with a single layer and with packed beds, the characteristic constants of the packings were determined and a correlation of the transfer coefficients was obtained. Furthermore, the discussion is extended to considerations of transfer phenomena in fluidized beds
