Drying Capacity Estimation based on Page's Equation

Calculations are based on Page's equation for thin layer drying (Page 1949). The model equation is: MR = exp(-k * t^n). MR is the moisture ratio (dimensionless). The constants k and n are empirical and need to be determined experimentally for each specific material and set of drying conditions. MR is computed as (Mf - Me) / (Mo - Me), where Mo and Mf are the initial and final moisture of the grain. Me is the equilibrium moisture content of the grain at the drying air conditions.

Typical drying time curves for an agricultural grain undering thin layer drying look like the figure above. Separate curves are shown for different ambient temperatures and relative humidity conditions. The k and n constants are used to fit one of these curves.

Factors that affect drying time:

• Initial and final moisture content
• Drying air temperature
• Airflow rate
• Grain type and variety
• Grain bed depth
• Ambient conditions (temperature, humidity)

The following is a link to an excellent guide to grain drying systems from UW-Madison.

Comments to the webmaster.

Reference: Factors Influencing the Maximum Rates of Air Drying Shelled Corn in Thin Layers. Page, Glen E.  1949.