Selected Physical Properties of Soybean In Relation To Storage Design

Engr. Onu John Chigbo Int. Journal of Engineering Research and Applications www.ijera.com
ISSN: 2248-9622, Vol. 6, Issue 2, (Part -6) February 2016, pp.71-75
www.ijera.com 71|P a g e
Selected Physical Properties of Soybean In Relation To Storage
Design
Engr. Onu John Chigbo
Department Of Agricultural Engineering Federal Polytechnic Oko
Anambra Statenigeria
ABSTRACT
Bulk density, kernel density, internal friction of Soybean were measured over a moisture content range of 7.4 to
22.22%(wb). First and second order polynomial equations are given which describe the kernel density, bulk
density as well as other properties’ dependence on moisture content. For the grain that was tested, bulk density,
kernel density and specific gravity decreased with moisture content while angle of repose, angle of internal
friction and coefficient of sliding friction increased as moisture content increased. One thousand grain weight
and average diameter increased with moisture content for the crop. Frictional coefficients of the crop was
measured on four structural surface namely: concrete, wood, galvanized sheet metal and mild steel sheet. The
values were maximum for concrete among the four surfaces. The angle of repose was found to be higher than
angle of internal friction in all cases tested. These measurements are necessary in selection of the material and in
determination of pressures and angles of the wall of storage structures.
Key words- Bulk density, Kernel density, Specific gravity, Internal friction, Moisture content, Physical
properties.
I. INTRODUCTION
Background Of The Study
Generally, physical properties of agricultural
products are needed in design and adjustment of
machines used during harvesting, separating, clearing,
handling processing and storing of agricultural
materials. The properties which are useful during
design must be known and these properties must be
determined with the appropriate cultivars. The grain
storage structures are designed to have vertical walls
for the primary storage volume and a conical bottom
for effective material discharge. Different structural
materials are used in constructing the silo walls. In
some mechanized storage systems, the bottom is
made flat while an unloading device is installed. In
each case, most of the properties needed to predict the
grain storage pressures are the physical and
mechanical properties. The use of belt conveyors to
convey granular agricultural solids along inclined
paths in agro-industrial plant is fast gaining
popularity. In such case, if the belt is inclined near the
permissible angle of inclination, the materials may
slip or fall back. The permissible angle at which there
is no flow back of the materials is influenced by the
coefficient of friction between the belt and the
materials as well as the angles of repose and internal
friction of the materials. In addition, the
determination of the capacity of the belt conveyor
requires that the bulk density of the grains be known.
Since most of these properties are influenced
by other properties it is often desired to determine
each property under a given set of conditions or
states. Moisture content for instance, influences
almost all grain properties, while specific gravity has
been found to have a good correlation with moisture
content and angle of repose of granular agricultural
materials (Ezeike 1988). Information on values of
these properties is at the moment grossly inadequate
for our local grains. The result is that designers in
agricultural engineering are made to make
assumptions that may not be safe for designs.
There appears to be a very few published
work on design-based properties of most Nigerian
crops. These properties are needed to plan and design
handling, processing and storage for these crops.
This work is aimed at experimentally
determining the physical properties of grain in
relation to storage designs. To be able to accomplish
this project, the crop which is grown in Nigeria and is
highly valued for its food and feed qualities was
chosen. The selected crop is Soybean, Glycine max.
(L.) Merril.
Soybean
(Glycine max L. Merril) belongs to the
family leguminosae. It originated from east of Asia
(Ogundipe, 2003). It ranked very high among the
leguminous crops in the world in both protein content
and general nutritional quality. It has different
varieties varying in shape, color, size, physical
properties and chemical composition (Wickel et al;
1979). It grows well in moderately sloppy soil, with
moderate drainage.
RESEARCH ARTICLE OPEN ACCESS

The mature soybean seed has three major
components; the seed coat (hull), the cotyledon and
hypocotyledon constituting 8%, 90% and 2% of the
seed respectively. The composition of soybean seed
expressed as percent dry weight is presented in Table
1
Table 1 Composition of soybean and seed parts
expressed as % dry weight.
Components Yield Protein Oil Ash Carbohy
drate
Whole
soybean
100 40 21 4.9 34
Cotyledon 90 43 23 5.0 29
Hull 7.3 8 1 4.3 86
Hypocotyls 2.4 41 11 4.4 43
(Source: (Osho, 1988).
II. MATERIALS AND METHOD
Experimental Procedure
Angle Of Repose:
The equipment that was used for the
determination of angle of repose is a box of 430mm
long, 200mm wide and 430mm high. This equipment
was used by Muir and Sinha, (1987) to determine the
angle of repose of cereal and oil seed cultivars grown
in western Canada. The angle of repose was measured
by filling the box with the grain sample to depth of
about 350mm and allowing it to flow out through a
50mm high rectangular opening along the bottom of
the width.
The sloping profile of the grain after flow
was determined using the geometry of the box and the
profile.
The angle of repose (Ør) was calculated as
follows;
Where, Ør = angle of repose in degrees
h = height of the grain profile at a distance
L = distance from the gate.
Bulk Density
This involves the use of hopper with top
diameter of 225mm, a bottom diameter of 38mm and
a height of 160mm for filling a 500ml container from
a height of 45mm above the top of the container. A
flat slide gate on the bottom of the hopper is used to
control the flow of grains. The excess grain in the
container is struck off with a straight edge and the
mass of grain in the cup is measured. Bulk density
was determined by dividing the mass of grain in the
cup by the bulk volume.
Kernel Density:
The kernel density is determined by dividing
the kernel mass by the volume found by fluid
displacement. To find the volume of the grain kernels,
the grains will be dropped in a graduated tube
containing some water enough to cover the grains.
The rise in the level of water in the tube is used to
determine the volume of the grains since objects
displace their own volume of fluid in which they are
completely immersed. In this work, the grain density
tube will be used with water as the fluid which the
grains were smeared with light grease to avoid
absorption of water.
Angle Of Internal Friction (Øi)
The direct shear test was used to determine
the coefficient and angle of internal friction of the
grains in this work. The material to be tested is put
into the inner split shear box as shown in fig 12. The
shear force is applied horizontally to the sample by a
motor-driven push rod. The shear load applied to the
sample is recorded by means of a proving-ring
mounted on a horizontal plane. Deformation of the
proving-ring monitored by a dial is related to the
shear load applied by means of a calibration graph.
As the shearing of the sample progresses records of
time, proving-ring dial gauge and vertical
deformation dial gauge are throughout the test until
shear failure of the sample occurs. The point of
failure is signified by a fall-off in recorded shear load
for proving dial gauge with continued separation of
the two halves of the shear box.
Sliding Friction (Fs)
The direct shear box apparatus is modified
and used for determination of coefficient of sliding
friction of grains. The surface to be tested is cut to the
size of the split-shear box. By this, the shear surface
coincided with surface of the test material as shown in
fig. 13. The upper half of the box is filled with the
grain to be tested on the surface in the lower half.
Apart from these modifications, the procedure is the
same as that of internal friction.
III. RESULTS AND DISCUSSION
TABLE 2: Mean values of angle of repose, bulk
density, kernel density, angle of internal friction,
specific gravity and moisture content of soybean

TABLE 3 Mean values of coefficient of sliding
friction of soybean on various structural surfaces.
The experimental results for angle of repose are
shown in Table 2. It was observed that angle of
repose changed from 33o
to 39o
when the moisture
content of soybean varied from 7.4 to 22.22%(wb);
Analysis of variance showed that moisture content
had a high significant effect on the angle of repose of
the crop at 1% probability. The regression equation
relating the angle of repose of the crop and its
moisture content is shown as:
Ør = 33.2 – 0.167Mc + 0.0193Mc3
(for soybean) – (1)
Coefficient of correlation R = 0.997
A multiple regression analysis by method of least
squares for the best-fit to correlate the angle of repose
of the crop and moisture content, bulk density and
kernel density was
Ør = 100 – 0.0764 – 0.0646pb – 0.0231pk
(For soybean)
Coefficient of correlation r = 0.999
The plot of angle of repose versus moisture content is
shown in Fig. 1
Figure 1: Angle of Repose of Soybean vs. Moisture
Content
Bulk Density
The values of bulk density obtained
experimentally are shown in Table 2. The moisture
content increase resulted in decrease in the values of
bulk density for the grain studied. The values of bulk
density varied from 731 to 658.36kg/m3
for soybean
as the moisture varied from 7.4 to 22.22% wb. Fig 2
shows the plots of experimental values of bulk
density versus moisture level of soybean. The bulk
density of the grain was found to have the following
relationships with moisture content:
Figure 2: Bulk Density of Soya bean vs. Moisture
Content
0027.78.4  eMcb
 (for
soybean)……………………………………(2)
ℓb Correlation coefficient R = 0.9521
Kernel Density
Like bulk density, kernel density was found
to vary inversely with moisture content of the grain.
For soybean it varied from 1266.10 to
1159.74 kg/m3 when the moisture varied from 7.4 to
22.22%(wb). Using least square method a polynomial
for the best fit to correlate the grain kernel density
and moisture content was obtained.
Specific Gravity
The specific gravity of the crop at their
various moisture ranges are shown in table 2 for
soybean. The moisture content ranges are 7.40 to
22.22% (wb) in that order. It was observed that
determined values decreased with increase in
moisture content in the range studied. The following
equations give the relationship between the specific
gravity and the moisture contents of the grain crop:
522.524.00032.0
23
 McMcMcS (for
soybean)……………………….(3)
R = 1
The plot of specific gravity versus moisture content of
the grain is shown in fig 3 below for soybean.
Figure 3: Specific Gravity of Soybean vs. Moisture
Content

Coefficient of Sliding Friction
The experimental results showing the
variation of coefficient of sliding friction of the grain
on structural surface are shown in table 3. This
dynamic coefficient of friction was observed to
increase as the moisture content increased for the crop
on the four structural surfaces.
Table 3 summarized the values of coefficient
of sliding friction of soybean on wood, galvanized
sheet metal and mild steel sheet. The regression
equation for the crop on four surfaces are given
below:
The bar chart of coefficient of sliding
friction of the grain on the four structural surfaces are
shown in Fig. 4 for soybean.
Figure 4: The bar chart of coefficient of sliding
friction for Soybeans
Angle of Internal Friction
The values of the angle of internal friction of
the grain crop tested in the experiment were observed
to increase with moisture content as shown in table 2.
The increase was observed for soybean. The analysis
gave the following regression equation relating the
angle of internal friction (Øi), moisture content (Mc)
and angel of repose (Ør).
 tan193.072.019.10  Mci
(for soya
bean)………………………….(4)
The plot of angle of internal friction versus moisture
content is shown in fig. 5 for soybean.
Figure 5: Angle of Internal Friction of Soya
bean vs. Moisture Content
IV. CONCLUSION
This experimental investigations of various
properties of the grain revealed the following:
(1) The bulk density and kernel density decrease with
moisture content over the moisture range from 7.4 to
22.22% for soybean.
(2) The specific gravity decreased with moisture content
for the moisture range from 7.4 to 22.22% for
soybean.
(3) The dynamic angle of repose (emptying)
increases with increase in moisture content of the
grain for moisture range of 7.4 to 22.22% (wb) for
soybean.
(4) The angle of internal friction has a high correlation
with moisture content but differs from angle of repose
for the grain studied. The values of internal friction
are lower than the values of angle of repose as can be
seen in previous figures.
(5) The dynamic coefficients of sliding friction of
soybean increases with moisture content and
significantly differs from surface to surface for the
four surfaces studied. Among concrete, wood,
galvanized sheet metal, and mild steel sheet, the
values of the coefficient of sliding friction are
maximum with respect to concrete.
The values determined in this work compare
favorably well with those reported in literature.
RECOMMENDATION
More research is needed in the area of
physical properties of our local agricultural products
under our local conditions. This is the only way to
generate data that will be appropriate to our
indigenous designs. Design and development of
devices to study these properties should be embarked
on as a matter of urgency, since the modification of
the imported ones for our local crops often introduces
errors that could be mistaken for treatment effects.
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