bH Flender MD Special mounting positions Wate B4-VH28-B Bevel-helical gearbox B4

Flender/Flender Gear Units/Bevel-helical gearbox B4

ta. In recent years, these have become more popular tot the empirical data. Brooker et al. ( have discussed details of various models. Sun and Woods ( have provided useful review of the equilibrium moisture data and models for wheat alone. modied form of the Henderson equation had been adaptedby the American Society of Agricultural Engineers (ASAE) as standard equipment for Fig. 5 Water activity versus moisture content plot for different types of food. Grain Drying Basics 1 Fig. 6 Deterioration rates as function of water activity for food systems. various grains. For various grains and over specic relative humidity ranges, different models have been reported to be better than the modied Henderson equation. For the purpose of design calculations, however, most models are within the range of engineeringaccuracy. The modied Henderson equation has the following form: 1/H1RH/H1exp[/H1k(/H1C) (1 )] where RH/H1relative humidity /H1dry basis moisture content (fractional) /H1temperature, in Kelvin ,,/H1experimental constants for grain Table 4 is list of values of ,, and Cfor selected grains. Table 4 Values of Constants in Henderson Equation Grain /H1nc Barley 2.2 2.0 1.2 Beans 2.0 1.8 2.2 Corn 8.6 1.8 4.8Rice 1.9 2.4 5.1 Sorghum 0.8 2.4 1.7 Wheat, durum 2.5 2.2 7.3 1 Mujumdar and Beke Table 5 Constants in Chung and Pfost ( Model Grain ABC Barley 0.3 0.0 9.3 Corn 0.3 0.0 3.2 Rice 0.2 0.0 3.7 Wheat 0.3 0.0 1.3 Another empirical model in common use, proposed by Chung and Pfost (, is described by /H1A/H1Bln[/H1(/H1C) (RH)] where ,, and Care empirical constants for given grain. Table 5 lists values of these constants for selected grains. Note that some grains display hysteresis phenomenon. For drying calculations the desorption isotherm is the entity of interest. From the moisture description isotherms at various temperatures the heat of vapor- ization hvof moisture from grains at different moisture contents and temperatures can be computed using the Clapeyron equ