FACTORS AFFECTING THE DRYING RATE CONSTANT IN THE FALLING RATE PERIOD

Abstract

The rate constant in the falling rate period of drying process was considered by assuming an equilibrium sorption condition in the materials. The rate constant, k, was expressed by the following equation: k=αn/Vo where, α, n and Vo were the coefficient determined by temperature and water vapor pressure, the constant in Halsey equation described the sorption isotherm, and the water regain after drying, respectively. The experimental k values were in good agreement with the calculated values for the natural fibers having small k values. In the case of synthetic fibers and low humidity which gave large k values, the experimental k values were smaller than the calculated ones.