Planting earlier-maturing varieties and drying corn in the field is more energy efficient than mechanical drying but may not be as cost effective in all situations as mechanical drying.
The most energy-efficient high-temperature drying uses the maximum drying temperature that will not damage grain. Using vacuum cooling or a heat-recovery system increases the energy efficiency of a continuous-flow heating and cooling dryer by about 20 to 30 percent depending on the outdoor air temperature.
Natural air/low-temperature drying is a slow-drying system but very efficient if designed and operated correctly. If drying wheat keep the depth less than 18 feet and corn less than 22 feet to limit the resistance to airflow, enabling efficient airflow delivery. Select the fan type that provides the most airflow per horsepower at the expected operating static pressure.
Dryeration reduces the energy requirement of high-temperature drying by about 25 percent. Corn at about 130 degrees Fahrenheit (F) coming from the dryer is steeped in a bin without airflow for 4 to 6 hours. Two to 2.5 percentage points of moisture are removed during cooling in the bin. Then the corn is moved to a storage bin.
Mixed-flow dryers may be 10 percent to 20 percent more efficient than a typical high-temperature cross-flow dryer.
Carl Pedersen, North Dakota State University
