When Do I Turn On the Fans...

1. When Do I Turn On the Fans... And For How LONG??? Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

2. What’s the purpose? • Manage: • Temperature • Moisture • Properly managed.. • Preserves quality • Helps to prevent insects • 10% harvest lost every year • ½ due to poor storage procedures Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

3. What happens if we don’t aerate? • Cool air outside • Warm grain inside • Convection Currents • Move moisture • Wet or spoiled grainat the top-center and/or on the cold wall Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

4. What does aeration do? • Conditions grain and seed by • Lowering temperature in the grain • Equalizes temperature within the structure • Prevents moisture migration and condensation • Controls bacteria, insects, molds and mites Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

5. What does aeration do? • Little insect reproduction occurs below 60F • Eggs are controlled at 40F • 40F is tough to do in some areas • So fumigation is still required but can be reduced Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

6. When do we aerate? • At Harvest: • Leave fans on continually until exhaust T is close to same as (or less than) average air T • Usual day-night T difference is about 20° • When outside air is 10° below grain temperature • Ideal target is 40°, or as cool as possible Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

7. When do we aerate? • Cool in 15 to 20° stages • Example: • If grain is 80°, wait for 55 - 65° weather and cool until grain is cooled to that range • Then wait for the next drop of 15° to aerate again. • Monitor grain weekly to detect heat increases Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

8. How long will it take? • Goal: to move the cooling front through the grain bulk. • Depending on the season (1/10 cfm/bu): • Summer: 80 hours • Fall: 120 hours • Winter: 160 hours • Half that time if you use 0.2 cfm/bu Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

9. How do we know T? • Thermocouples throughout bin • Permanently installed • Hung on cables • Pipe with thermometers • Temperature probe at least 3’ long • CO2 monitor at exhaust of fan • Change indicates insect or mold activity Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

10. So what about RH? • Regardless of RH, harvest heat has to be removed • Then… • Equilibrium Moisture Content (EMC) RULES ! • Point at which grain and air don’t exchange moisture Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

11. So what about RH? • Example Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

12. So what about RH? • 1 – 2 days of rainy weather causes very little change in MC • Takes much longer to change MC than to change T Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

13. So what’s the plan? • Summary: • Run fans night and day at binning until exhaust fan T is close to average daily T • Then run fans only when air T is 10° less than grain until grain is about 40° if possible • After desired T, operate a few hours each week to prevent musty odors Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

14. Manual or Automatic? • Small grain storage: Manual • Requires temperature and humidity information • Thermometer and hygrometer • Larger bins: Automatic • Automatic will pay for itself by preventing shrink from over-drying and saving labor Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

15. Automatic Controls • Requires humidstat and thermostat Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

21. Results of over-aeration • Grain shatter • Grain is too dry • Temp. has dropped too quickly • Excessive shrink • Moisture can be added, but it’s slow and takes additional air capacity…careful monitoring Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

22. Words of Caution • Make sure T front has moved all the way through grain bulk • Negative Pressure System: open vents before starting fans • Positive Pressure System: watch for roof condensation…open vents • Don’t cut corners on aeration…it never pays! Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

23. Resources • EMC Tables Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

24. Resources • EMC Tables (wheat, corn, soybeans) http://www.grainqualitycontrol.com/emc_drying.htm • Temperature Probe Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

25. Resources • Hygrometer Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

26. Resources • Commercial controller Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

27. Resources • Commercial controller (OPI System) Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.

28. Resources http://biosystems.okstate.edu/Home/jcarol/index.html Questions Carol Jones, PhD. Stored Product Engineering Biosystems and Ag. Engr. Dept.