Applying Technology for Agriculture

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2 Previous PAMI work Project goal Small scale testing set-up Large scale testing of control strategy Implications of results Potential future work

3 Wet/hot grain will spoil Natural air drying = aeration w/o heat addition Systems are common but not used efficiently Through-dry means grain at bottom is over dry Fan running but not drying Air needs to have capacity to dry Manual control involves a lot of guess work

4 : Effects of combination drying Effects of heating inlet air during NAD Verification of temperature fronts as an indication of drying uniformity

5 1988: NAD control system to prevent overdrying, prediction of drying time Performance of NAD distribution systems Fully perforated floors, Helfer Duct (Y), straight, V, cross ducts, etc. Images from

6 1991: In-grain moisture content measurement Dielectric capacitance Equilibrium RH 2004: Automation of NAD systems Review of modeling research Instrumentation and data required for control system

7 To develop a control system that will automatically turn fans on/off Set it and forget it Prevent over-drying of grain Reduce energy costs (and GHG emissions) The envisioned control system should Be proactive rather than reactive Allow estimation of moisture content profile

8 Moisture content of the air in the grain voids will be equal to the moisture content of the grain Moisture content of the air can be calculated from air temperature (T) and relative humidity (RH) using Equilibrium Moisture Content (EMC) equations Henderson EMC: MC db = ln(1 RH ) K( T C) + 1 N ASAE Standard D245.5, 2005

9 Temp Relative Humidity (%) C

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11 Monitoring in all bins Mass, temp/rh at inlet, temp/rh at outlet, static pressure, fan speed L1 L2 L3 L4 L5 L6 HT1 HT3 HT5 HT11 HT13 HT15 HT6 HT16 Bin 1 Bin 2 HT7 Bin 3 Bin 4 Bin 5 HT17 Bin 6 Monitoring in bins 3 and 6 Grain temp/rh at 4 depths HT8 HT18 HT9 HT19 P1 P2 P3 P4 P5 P6 HT21 HT4 HT10 HT12 HT14 HT20 FS1 FS2 FS3 FS4 FS5 FS6

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13 Actual MC

14 Henderson EMC: MC db = ln(1 RH ) K( T C) + 1 N

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16 Temp Relative Humidity (%) C

17 Does any MCgrain = MCmax (> 17%)? Yes Fan ON No MCgrain Max = MCmin ( %) MCgrain Max = MCmid ( %) MCgrain Max = M C dry ( %) MCgrain Min = MCoverdry (< 13%) MCambient = D ry (< 14%) MCambient = Neutral ( %) MCambient = W et (> 14.5 %) MCambient = D ry (< 14%) MCambient = Neutral ( %) MCambient = W et (> 14.5 %) MCambient = W et (> 14.5 %) Fan ON Fan OFF Fan ON Fan OFF Fan OFF Fan ON

18 Wheat (15.8% wb) loaded Sept 15 Grain was average dry (14.4%) on Sept days total Fan was on 45% of time (137 of 306 hrs) Testing of re-wetting cycle started on Sept 30 Final calculated moisture contents Bottom 14.4% Middle 12.3% Top 14.6%

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20 Effect of ambient air moisture content on fan cycle Ambient Air MC (%wb) Time (hrs) 2 Fan cycle (0 = off, 1 = on) 16 The diurnal variation of ambient air moisture content meant that air had potential to dry from approximately 10 am to 10 pm on most days. Effect of fan cycle on grain moisture content (bottom grain) 2 Drying occurred when the fan was on. When the fan turned off, some equilibration or slight rewetting occurred. Grain MC (%wb) Fan cycle (0 = off, 1 = on) Applying Time Technology (hrs) for Agriculture

21 5 hp fan running continuously for 30 days = 2,980 kw-hr of electricity Cost to run fan continuously (10 cents per kwhr) = $300 per month By optimizing the operating cycle of the NAD fan, a farmer can save approximately $150 per operating month per fan Also, reduced chance of grain spoilage or overdrying and reduced labour (more $$ impacts)

22 Each bin would require At least 4 temp/rh sensors (three in-grain and one at inlet) Relays to switch fan on/off Each set up (for up to 10 bins) would require Controller to execute algorithm Interface for input information (grain type, starting MC, etc.)

23 OPI-integris (Calgary based) Control of aeration, drying (with heat) and ventilation Designed for large bins (100,000 bushels +) Complex, costly system Aeration Control (Australia) Drying, aeration, and conditioning control for large silos In-grain moisture predicted based on info during loading and weather during fan hours

24 PAMI CFD, discrete modeling of airflow in bin Useful for design and optimization of new inlet/outlet configurations Indian Head Research Farm (IHARF) Mass balance approach for control strategy Side by side trials in fall, 2011

25 Control strategy work Side by side small scale and full scale testing Optimization of control strategy (setpoints, frequency of decision routine, cooling cycles, etc.) Development and refinement of calculations to calculate grain moisture content for different grains Analysis of the impact of starting and stopping the fan on the drying/cooling front Other grain storage work Grain bag storage Natural ventilation systems

26 NAD systems require guess work In-grain temp/rh can be used to calculate grain MC Control strategy based on grain and inlet MC was implemented Full scale run suggests that fans should operate only 45% of time More development and refinement required Existing products not feasible for small producers

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