During heating the absolute humidity remains constant at HA whereas the relative humidity falls from hA to hB. As air moves through the grain bed it absorbs moisture. The air will have increased in both absolute humidity, Hc, and relative humidity, hc, but fallen in temperature, Tc. Physical Properties of Grain Comprehensive data on the numerous physical and thermal properties of grain are available in texts such as Brooker et al. Moisture Content . Conversion between the two measurements is shown in Table 5.2.
All moisture contents given in the text are on a wet weight basis, unless otherwise stated.
Conversion of Moisture Contents. 38.9 29.0 40.8 30.0 42.8 Bulk Density . The bulk density of grain is the weight per unit volume. Resistance to Air Flow . The energy required to force air through a bed of grain is dependent on the air flow, the grain depth and physical properties of the grain such as surface and shape factors, the kernel size distribution, moisture content, and the quantity and nature of contamination, stones, straw, weeds etc.