Low Temperature Drying

Low Temperature Drying (LTD) in Bins

     With LTD systems a crop can be harvested tough or damp. This system uses a good quality bin aeration system that will distribute airflow evenly in the bin, a mid to high volume aeration fan, and a low temperature heater that will raise air temperature by approximately 10 degrees F ( 5.5 C).

     As described in the natural air drying (NAD) section, drying only occurs in a bin when the EMC (equilibrium moisture content) of the air being moved through the grain is within the drying window. Our goal with a low temp heater is to simulate a nice August afternoon 24 hours a day to shorten the amount of time required to dry the grain in your bin. The most important thing to remember when operating LTD systems is to add only as much heat as needed to reach your target EMC. Adding extra heat beyond your target EMC will over dry the bottom of your bin.

     If you would like more information on EMC please CLICK HERE.

     If you would like more information on NAD please CLICK HERE.

     Adding heat to an aeration system does two things. First of all the temperature of the air going into the bin is increased. Secondly the heated air will have a lower relative humidity. Both of these factors lower EMC. Therefore a small temperature increase from a supplemental heater can have a very large effect. Below is a chart listing normal temperatures/relative humidities for Manitoba:

			AUGUST
Time of Day	Normal Temp	Normal Rel. Hum.	EMC Wheat	EMC Oats	EMC Barley	EMC Canola	EMC Sunflower	EMC Soybean
7:00 AM	58F/14C	84%	18.7	16.7	18.9	13.3	N/A	N/A
1:00 PM	73F/23C	54%	12.6	10.8	12.4	6.9	N/A	N/A
7:00 PM	70F/21C	62%	13.9	12.0	13.8	7.9	N/A	N/A
1:00 AM	59F/15C	82%	18.2	16.1	18.3	12.5	N/A	N/A
Approx. Hrs/Day of Drying			17	17	16	18	N/A	N/A

As shown above little drying will occur between the hours of 11:00 PM and 7:00 AM because the EMC is out of drying range. The chart below shows how adding 10 degrees F of heat through the night improves the drying time dramatically. NOTE: If you leave the heater on during the day the EMC will be below the desired level and over drying will occur.

			AUGUST
Time of Day	Heated Temp	Heated Rel. Hum.	EMC Wheat	EMC Oats	EMC Barley	EMC Canola	EMC Sunflower	EMC Soybean
7:00 AM	68F/19C	59%	13.6	11.7	13.3	7.6	N/A	N/A
1:00 AM	69F/20C	58%	13.4	11.5	13.1	7.5	N/A	N/A

     If you would like a copy of a program that calculates EMC for ambient and heated air contact Avonlea (avonlea@grainbins.com) and we will email it to you.

     The most important thing to remember is that a little added heat dramatically lowers the relative humidity of the air, which in turn lowers EMC.

     Use of bin temperature cables to monitor your bins is recommended. If you would like more information on bin temperature cables please CLICK HERE.