Aeration Strategy Simulations for Australian Wheat Storage Ben Plumier

Introduction  Australian sub tropical climate encourages insect growth and causes grain storage problems  Aeration is more difficult than in the US  Fumigation is heavily relied upon for Australian insect control strategies

Phosphine Resistance  Increasing insect resistance to fumigants leads to a need for better understanding of fumigant behavior and grain storage practices  Majority of grain in Australia does not meet gas tightness standards (Darby 2011).  Genetic phosphine resistance is increasing in Australia, common even where fumigations aren’t used (Kaur et. al, 2013).  Environmental factors can have significant effect on fumigations (Cryer and Barnekow, 2006)

KSU 3D Model  Governing differential equations evaluated over a number of discretized elements

3D Model Implementation  Build mesh for grain ecosystem and designate sampling points  Acquire and assemble weather data, Temp, RH, Solar Radiation, Wind Speed  Decide and code for aeration strategies

 Weather data from Coreen, NSW  3 years , ,  3 aeration rates,.1 cfm/bu.3 cfm/bu.6 cfm,/bu  6 aeration strategies  Monitor 5 points for T and MC in middle of bin, increasing in height  Runs from Nov 26 th to Oct 31 st Aeration Simulation

Aeration Strategies Simulated  1. Aeration always on  2. T<20 o C 9%<EMC<14%  3. T< 20 o C  4. 6am-8am 7pm-9pm  5. T outside < grain T  6. T outside < grain T 9%<EMC<14%

Strategy 1. Aeration always on  Initially heats grain  Grain is susceptible to rapid temperature changes as each successive weather front comes through  Inefficient

Strategy 2. T<20 o C 9%<EMC<14%  Average of only 655 fan run hours  Even at high airflow rates unable to cool grain below 15 o C

Strategy 3. T< 20 o C  Average of 2414 fan run hours  Can cool grain quickly Low aeration rateMid aeration rateHigh aeration rate under 155/3/13 16:00under 153/3/13 6:00under 1512/28/12 21:00 under 106/20/13 20:00under 105/14/13 7:00under 105/9/13 21:00 minimum8/22/13 6:00minimum7/2/13 15:00minimum6/24/13 8:00

Strategy 3. T< 20 o C  At low airflow rates, grain temperature is not uniform  At high airflow rates, higher fluctuation and EMC problems  Most of those problems occur late in the year, after the grain has been cooled  Can provide useful cooling even at low airflow rates

Strategy 3. T< 20 o C

Strategy 4. 6am-8am 7pm-9pm  2040 Fan run hours  Initially heats grain  Achieves significant cooling only under high Airflow rate

Strategy 5. T outside < grain T  Very effective at lowering temperature  Can get below 10 o C even at low airflow rate  Typically mild EMC problems, only occurring at lowest and highest location in bin  Fewer fan run hours at higher fan run speeds  Larger temperature variations in bin, especially at low aeration rates LowMidHigh Total Fan Run under 155/3/13 23:003/6/13 0:0012/30/12 6:00 under 106/19/13 10:005/4/13 6:004/15/13 7:00 minimum9/3/13 7:0010/4/13 21:009/26/13 5:00

Strategy 5. T outside < grain T

Low Aeration Rate Mid Aeration Rate High Aeration Rate

Strategy 5. T outside < grain T

Strategy 6. T outside < grain T 9%<EMC<14%  Low fan run hours, ranging from depending on aeration speed  Even at high airflow rates unable to cool grain below 15 o C

Conclusions from Aeration Simulations  Strategies relying on EMC windows typically do not have enough fan run hours  Strategies without EMC considerations typically did not have significant MC problems until grain was already cool  Strategies 3 and 5 were superior to the other strategies tested  Strategy 3 may be improved simply by turning fan off once low temperatures have been reached, is probably better than 5 at low airflow rates  Strategy 5 cools even faster than 3, is clearly superior at higher airflow rates