New Insight into Natural Aeration Grain Drying 16 10 9 17 18 19 Ron Palmer P.Eng. Ph.D. Prairieland Park Hall A Rm #1 [email protected] 503 Ruth St. W. Saskatoon SK Indian Head Agricultural Research Foundation Thurs January 14, 2016 10:00 AM Common Practice: Fan on Continuously  The Set-up 2007, Data Collected  Objectives  Vapour Pressure  Water Balance-In/Out, Diurnal Cycle, Yard Light Rule  Cooling is Drying  Fan On if: Grain Temp > Air Temp  Safe Grain, Number of Safe Days, Spoilage Index  EMC equilibrium moisture content, the calculator  Dripping, crusting – why? Prevention  Comparing Fan Control Strategies: Best to Worst  Review: Points to Take Home  Future Work  Questions ??  Fan on continuously.  Keep that drying front moving.  Don’t need aeration fans if grain stored “dry”.  Need heat to dry, so maybe only turn on  during the hot days? Regarding fans: The bigger the better!  To dry: 1 CFM/bu. To cool: 0.1 CFM/bu.  Cold air does not dry grain.  Turn the fan on when conditions are right.  The Experimental Setup Amount of Air Out = Amount of Air In Sensor measuring T and RH of the air leaving the bin • Each Sensor ‘s value was recorded every hour. • Fans were run continuously • Data has been collected every year since 2007 Sensor measuring T and RH of the air entering the bin Air flow measured with pitot tube in CFM RH and Temperature Probe On Inside Top of Bin Recording RH and To. Temperature Sampling ports Probes for Grain Moisture 10-LOW 10-MID 10-HI LEVEL LEVEL LEVEL 10-DISCH 10-DISCH 10-FAN Date / Time TEMP TEMP TEMP TEMP HUMID CFM Outside T Outside RH 09/02/2011 9:58 18.13 37.88 30.3 25.41 90.06 2882 14.54 75.38 09/02/2011 10:58 17.64 29.84 31 31.94 86.94 2502 17.25 66.31 09/02/2011 11:58 17.7 22.02 33.06 30.23 85.5 2732 16.75 70.69 09/02/2011 12:58 18.27 17.55 29.94 29.64 87.88 2600 17.14 71.81 09/02/2011 13:58 18.83 15.82 25.78 29.63 87.06 2014 17.22 74 09/02/2011 14:58 19.22 15.73 22.3 27.8 83.38 2504 18.17 68.75 09/02/2011 15:58 19.41 15.78 19.64 26.56 76.44 2780 22.25 53.88 09/02/2011 16:58 19.17 15.97 17.98 23.45 76.56 2994 21.5 50.75 09/02/2011 17:58 18.97 16.06 17.25 20.7 77.56 3456 15.15 67.69 09/02/2011 18:58 18.41 15.82 17.16 19.06 77.31 3154 15.4 65.13 09/02/2011 19:58 17.83 15.34 17.16 17.83 78 3094 14.38 73.06 09/02/2011 20:58 17.73 14.29 17.16 17.34 78 3420 14 78.06 09/02/2011 21:58 17.98 13.72 16.88 16.97 78.69 3118 13.33 86.81 09/02/2011 22:58 18.08 13.71 16.3 16.97 78.06 3106 13.2 84.56 09/02/2011 23:58 18.02 13.96 15.63 16.78 78 3362 12.37 87.94 09/03/2011 0:58 17.25 14.05 15.16 16.11 79.13 3420 10.61 91 09/03/2011 1:58 16.59 14.05 15.05 15.3 80.88 3680 10.61 97.31 09/03/2011 2:58 16.59 13.42 15.05 15.02 79 3580 10.78 94.63 09/03/2011 3:58 16.39 12.95 15.05 15.02 77.63 3486 10.7 93.38 09/03/2011 4:58 16.02 12.95 15.05 15.02 77.75 3552 10.61 91.31  To find out what is going on? When is there drying? To design a management practice to control the  fan:  Dries Grain to market-dry level standards  Is efficient – saves power, fan on only when necessary (if drying: fan on -- if not drying: fan off)  Provides Safe Grain Storage – i.e. No spoilage, no loss of grade, no infestation of molds, fungus, toxins (OTA)  Cool grain  Dry grain Grain Air kernel surrounding kernel Water trying to get out Water trying to get in = Vapour Pressure Grain = Vapour Pressure Air • % moisture content • temperature • temperature • relative humidity • type & condition of grain When air vapour pressure is greater When grain vapour pressure is greater than grain vapour pressure, water than the air vapour pressure, water enters the grain and WETTING occurs. evaporates from the grain into the air When Vps are equal,  EMC and we have DRYING Psychrometric Charts: W = 0.000289 T3 + 0.010873 T2 + 0.311043T + 4.617135 s 45 Water in the Air r e 40 t e m 35 Saturation RH= 100% c i b Relative Humidity (RH) u 30 c • a percentage of Saturation r 3 • AbsHum/Saturation AbsHum e m 25 p r / r e g t 20 a Air at 20⁰ C can only w hold 17 grams water per f 15 cubic meter. At 20⁰ C o and at a relative s m 10 humidity (RH) of 50% a the absolute humidity is r g half of 17 or 8.5 gr/m3. 5 0 -30 -20 -10 0 10 20 30 40 Temperature of Air Degrees Celsius ⁰C