World Grain - April 2022 - 48

GRAIN OPERATIONS
ment of a cooling front through peaked and
un-cored grain, given it will take substantially
longer (perhaps as much as two to
three times longer) to move a cooling front
through the peak of a grain mass compared
to the shallower periphery layers.
Temperature monitoring
during storage
The general recommendations for temperature
cable placement throughout the
grain mass, particularly in the center (or
not) and at what distance from the sidewall
needs further analysis. Grain is an
excellent insulator, and if un-peaked and
cored will stay cold after aeration cooling
for many months, especially when
aeration fans are sealed (covered) when
not operated.
Results were compared to sensors on three cables, one
placed in the center, and two at two-thirds of the radius.
Sensors were spaced 4.5 feet (1.4 m) along the cables for a
total of 30 sensors and 9 feet (2.7 m) along the cables for a
total of 15 sensors.
During the cool-down period while grain was aerated
with ambient air, the number of nodes - whether 15, 30
or 2,000 - and thus the number and placement of cables
did not affect the predicted grain temperature the stored
grain manager would have observed as the cooling front
advanced upward through the grain mass.
Thus, spacing of temperature sensors throughout the depth of a
cored and leveled grain mass provides useful information during
the cool-down period while placement of cables along the radius
less so. The exception applies when monitoring the advanceWarming
primarily will occur as a function of ambient
weather conditions, especially solar radiation on the sun-exposed
bin roof and wall surface areas. This cyclically warms
and cools the outer layers of grain near the bin wall and headspace
during the day and night, respectively. Thus, the question
arises where the placement of temperature sensors (and
thus cables) would provide the most useful data during the
grain storage period. Unlike the cool-down period, substantial
differences are observed in the predicted average temperatures
during the storage period.
The 15 temperature sensors spaced 9 feet (2.3 m) apart
along four cables provided as much useful information as the
average temperature predicted by 2,000 sensors. This contradicts
the intuition that more sensors will provide more useful
information to a stored grain manager.
Cable placement study
Bin
diameter
(ft)
36
42
48
54
60
72
78
90
105
135
156
48
Level grain
depth (ft)
36
42
48
54
60
72
78
90
105
110
106
Distance
from
center (ft)
9
14
16
18
20
27
29
36
44
59
70
Distance
to
wall (ft)
9
7
8
9
10
9
10
9
8.5
8.5
8.5
Radius to
wall (ft)
1/2
2/3
2/3
2/3
2/3
3/4
3/4
4/5
5/6
7/8
8/9
Cables
(#)
3
4
5
6
7
9
10
12
14
19
22
Wall surface
area (ft2)
4,072
5,542
7,238
9,161
11,310
16,286
19,113
25,447
34,636
46,653
51,949
Periphery
volume
(ft3)
27,483
32,327
48,225
68,707
94,248
128,252
166,630
206,120
270,574
371,580
417,510
V/S ratio
(ft)
6.8
5.8
6.7
7.5
8.3
7.9
8.7
8.1
7.8
8
8
Volume/
cable
(ft3)
9,161
8,082
9,651
11,451
13,464
14,250
16,663
17,177
19,327
19,327
19,327
April 2022 / World Grain / World-Grain.com
Photo courtesy of Rolfes@Boone, Source: Dirk Maier/Iowa State University
http://www.World-Grain.com
World Grain - April 2022

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