Natural Aeration Grain Drying – Ron Palmer

40 Pages·2016·3.45 MB·English

New Insight into Natural Aeration Grain Drying
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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