摘要：A rotating disc column (RDC) with inner diameter 68 mm and 28 compartments is used in this study. Parameters including Sauter mean diameter, hold-up and mass transfer coefficient are measured experimentally un-der different operating conditions. The correlations in literature for molecular diffusion and enhancement factor equation including eddy diffusion, circulation and oscillation of drops are evaluated. A new equation for the effec-tive diffusion coefficient as a function of Reynolds number is proposed. The calculated values of mass transfer co-efficient and column height from the previous equations and present equation are compared with the experimental data. The results from the present equation are in very good agreement with the experimental results, which may be used in designing RDC columns.

摘要：For obtaining the drying curve of powder under fluidized drying, a normal fluidized-bed dryer is designed to study the drying kinetics of PVC （polyvinyl chloride） powder in the experiment. A new measure system is derived for drying dynamics testing. In the small fluidized-bed dryer, fluidization parameter of PVC powder is tested, and the operating air velocity can be chosen in the range of 0. 41 to 0. 55 m/s. Accordingly, the fluidized number Ua/Umf is from 1.24 to 1.67. A promising drying model is used to describe the drying process, and then the characteristic drying curve of PVC powder derived from a suspension method can be expressed as f = [-0. 622 6 ＋ 1. 254 6exp（2. 561 5Φ -0. 707 2） /[1 ＋ exp（2. 561 5Φ -0. 707 2）] Based on the experiments, the critical moisture content xc and the mass transfer coefficient K are determined to be 0. 02 kg/kg and 6. 0 × 10^-4 kg/（ m2 · s）, respectively. The experimental results in the small fluidized-bed dryer are similar to those of the real fluidized drying process, so the descried method can also be used in determining drying kinetics of powder materials such as PVC powder.