ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY &
ENVIRONMENT

AZOJETE December 2020. Vol. 16(4):699-716
Published by the Faculty of Engineering, University of Maiduguri, Maiduguri, Nigeria.

Print ISSN: 1596-2490, Electronic ISSN: 2545-5818
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ORIGINAL RESEARCH ARTICLE

DEVELOPMENT OF MULTI SEEDS OIL EXPELLER

I. O. Olaoye1, Y. A. Salako2* and O. K. Owolarafe3
1Department of Agricultural & Bio-Environmental Engineering, The Oke – Ogun Polytechnic Saki Nigeria

2*Departments of Agricultural Education, Michael Otedola College of Primary Education, Noforija Epe, Nigeria
3Departments of Agricultural and Environmental Engineering, Obafemi Awolowo University, Ile-Ife, Nigeria

*Corresponding author’s email address: salthaqib@yahoo.com

1.0 Introduction
Edible vegetable oil is oil produced from any of the edible oil-bearing seeds that exist in nature.
Many of these seeds are produced in large quantities in Nigeria and have a lot of uses. Amongst
them are groundnut seed, oil palm fruit and kernel, soybean, cotton seed, sesame seed and
melon seeds (Bello, 2013). Hydraulic system (hydraulic press) is one of the most effective
methods of oilseed extraction because higher pressure may be attained. However, care should
be taken to ensure that poisonous hydraulic fluid does not come in contact with the oil or raw
material. Apart from this, there is frequent breakdown of the hydraulic system and hence
maintenance cost could be high. Additionally, oil extraction can also be achieved through
solvent extraction. This involves the use of organic chemicals to dissolve out the oil from the
seed. The seed must have been ground and placed in a semi permeable membrane before
placing in the solvent extractor. Solvent extraction is about the most efficient method of oil
recovery from oil bearing materials. Extraction of oil from oil bearing material with low oil
content (such as soya bean, rice bran and mango kernel) is best carried out using solvent
extraction. (Shukla et al., 1992). However, the resulting cake from the extraction process is
usually contaminated and may not be suitable for animal feeds. Oil expression is a mechanical
method for removing oil from oil-bearing materials. The raw materials are pressed under high
pressure. When used for the extraction of food oils, typical raw materials are nuts, seeds and
algae, which are supplied to the press in a continuous feed. As the raw material is pressed,
friction causes it to heat up; in the case of harder nuts (which require higher pressures) the

ARTICLE
INFORMATION

ABSTRACT
Multi seeds oil expeller was designed fabricated and evaluated using screw
press principle. It was designed and fabricated based on the data obtained on
the properties of the oilseeds. The performance of the machine was carried
out using a 3 x 3 x 3 factorial experimental design with the following type of
seeds (palm kernel, soya bean and groundnut seed), worm shaft speed of
47.6, 87and 92 rpm, and moisture content of 5, 10, and 15 % w.b as
factors. Data collected include oil yield, volumetric flow rate of oil, throughput
capacity and efficiency of the machine. The results showed that increase in
moisture content as stated has direct effect on oil yield and efficiency of the
expeller, but has an inverse effect on volumetric flow rate for the three oil
seeds. Increase in worm shaft speed as stated increased oil recovery for palm
kernel from 19.1 to 23.0%, soya beans from 0.0 to 16.0% and groundnut
from 7.3 to 31.7%. Increase in worm shaft speed as stated increased the oil
yield, throughput capacity as well as the efficiency of the machine for all the oil
seeds. The efficiency increased from 39.4 to 52.1%; 0.0 to 82.1% and 53.1 to
72.0% for palm kernel; soya bean and groundnut, respectively. These results
were found to be significant (p<0.05) when tested using one way analysis of
variance (ANOVA) and Duncan’s multiple range test. The study concluded
that, the developed multi-seed expeller performed well within the conditions of
operation and could have a potential for improving the production of vegetable
oil if adopted by small and medium scale processors.

© 2020 Faculty of Engineering, University of Maiduguri, Nigeria. All rights reserved.

Submitted 8 February, 2020
Revised 11 July, 2020
Accepted 18 July, 2020.

Keywords:
Screw press
Oilseeds
worm shaft
Throughput capacity and
Volumetric flow rate.

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Olaoye et al.: Development of Multi Seeds Oil Expeller. AZOJETE,16(4):699-716. ISSN 1596-2490; e-ISSN 2545-5818,
www.azojete.com.ng

Corresponding author’s e-mail address: salthaqib@yahoo.com 700

material can exceed temperatures of 120 °F (49 °C). An expeller press is a screw-type machine
that presses oil seeds pass through a caged barrel-like cavity. Raw materials enter one side of
the press and waste products exit the other side. The machine uses friction and continuous
pressure from the screw drives to move and compress the seed material. The oil extracted
from the seeds passes through small openings that do not allow seed fiber solids to pass
through. Consequently, the fiber from the pressed seeds are formed into a hardened cake,
which is removed from the machine (Agbogun, 2011). Pressure involved in expeller pressing
creates heat in the range of 140–210 °F (60–99 °C). Some companies claim that they use a
cooling apparatus to reduce this temperature to protect certain properties of the oils being
extracted (Olatunde et al., 2014).

There is an increasing demand for edible oil in Nigeria and the world as a whole. Statistics
show that the demand for vegetable oil keeps on increasing on yearly basis (Kojima et al., 2016).
The large scale plants (which though have high extraction efficiency) utilize sophisticated
equipment which are expensive and are always imported. Most of the existing oil expeller
machines for small and medium scale processors were designed for a particular seed. The
development of a multi-seed oilseeds expeller will provide an opportunity for farmers and
processors to have plant that can handle many oilseeds. This will reduce the cost of production
and enhance the productivity of the processors. In this study, a multi-seeds oil expeller was
designed and fabricated to expel all the oil bearing seeds for purposes of small and the medium
scale processors.

2. Materials and Methods
2.1 Design of the Components of the Oil Expeller
This machine was designed to expel oil from hard and soft seeds. The hard seeds selected are
palm kernel and soya seed while groundnut was chosen as soft seed. The expeller consists of
hopper, pressing chamber, differential unit, the discharge outlets (oil and cake outlets) power
unit and frame as shown in Figure 1. The material flows from hopper to the pressing chamber
which consists of a worm shaft beveled at the end. The expelled oil flows out of the oil outlet
after the frictional effect which causes heat in pressing chamber while the cake comes out of
the cake outlet.

i. The hopper
The design of a hopper depends principally on the mechanical behavior of the material. The
shape of the hopper is shown in Figure 2 was chosen to ensure free flow of both kernels and
nuts under gravity. The feeding rate was controlled by feeding control plate, this was done by
taking into consideration the angle of repose of the kernels. According to Kibar and Ozturk
(2008); Davies (2009) and Dagwa and Ibhadode (2008), the dynamic angle of repose from
experiment was determined to be 29.0° and 28.4° for groundnut and soya bean, respectively.
Let us assume that 1.5kg of oilseed was used per batch.
Average angle of friction of the seeds = 29.0°

Vs =
M
ρ
=
1500
853.6

= 1.76 m3 (1)

Where: Vs = Volume of seed
M = Mass of oilseed
ρ = Density of oilseed

The height of hopper was calculated thus:

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Arid Zone Journal of Engineering, Technology and Environment, December, 2020; Vol. 16(4):699-716. ISSN 1596-2490; e-ISSN 2545-
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Figure 1: Three dimensional view of the oil expeller

tan 29.0 = ℎ1
150.4

(2)

hI =150.5 tan 29.00
hI = 150.5× 0.55431
hI = 83.42 mm

Capacity of the piling hopper: the hopper can be divided into 3 segments and the volume of
each segment will be determine the overall capacity of the piling hopper.
Therefore capacity of the hopper was determined using the dimensions presented in Figure as:

Vt = V1 + V2 + V3 (3)

Vt = a × a × ℎ1 + ℎ2
3

a2 + b2 + a2. b2 + (b × b × ℎ3) (4)

Vt = 0.3556 × 0.3556 × 0.087 + 0.2
3

0.35562 + 0.092 + 0.35562 × 0.092 + (0.09 ×
0.09 × 0.08691)

Vt = 0.011 + 0.0111 + 0.000704
= 22.8 × 10-3 m3

The handling capacity of the hopper is 22.80 × 10-3 m3

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Olaoye et al.: Development of Multi Seeds Oil Expeller. AZOJETE,16(4):699-716. ISSN 1596-2490; e-ISSN 2545-5818,
www.azojete.com.ng

Corresponding author’s e-mail address: salthaqib@yahoo.com 702

Figure 2: Orthographic view of the hopper

ii. The wormshaft
The screw worm consists of ϕ40 mm × 550 mm spiral worm shaft. At one end of the screw
press shaft is a conical frustum with an angle of 45° with a length 125 mm and width of 87 mm
as shown in figure 3.

Figure 3: A cross- section of wormshaft

iii. Determination of wormshaft diameter
Assuming a power source of 35 kW as the prime mover for the machine, the tensional
moment (Mt) due to the applied load can be determined (Hall et al., 1980):

Mt =
9550 ×KW

Rev
min

(5)

Assuming that power = 35 kW and speed = 92.0 rpm

=
9550 ×35

92
Nm = 3633.2 Nm

Using the bending moment diagram in Appendix 1, the maximum bending moment (Mb) was
found to be:

Mb = 342.104 Nm

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Arid Zone Journal of Engineering, Technology and Environment, December, 2020; Vol. 16(4):699-716. ISSN 1596-2490; e-ISSN 2545-
5818; www.azojete.com.ng

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The diameter of the shaft was then determined using equation below. (Hall et al., 1980)
d3 = 16

πS
KbMb

2 + KtMt
2 (6)

Where:-
S is allowable shear stress
Kb is shock and fatigue factor for bending moment
Kt is shock and fatigue factor for torsional moment
Mt is torsional moment
Mb is bending moment
Where:
Ss = 55 MN/m2 (using a factor safety of 2.5)
Kb = 1.5
Mb =342.104 Nm
Kt = 1
Mt = 145.33 Nm

d3 = 16
π ×55 ×106

1.5 × 342.104 2 + 1 × 145.33 2

d3 = 4.938 × 10−5
d = 36.68 mm

iv. The screw length
The equation of a helix wound on the shaft is given by;
x = (r + mL) cos θ (7)
y = (r + mL) sin θ
and
z = (r + mL) Cot α (8)
x, y and z are the shaft axes. The length S of the helix curve is given by:
S2 = x2 + y2 + z2 (Hrankowski and Waldman, 2017) (9)

Hence
ds
dθ

2
= dx

dθ

2
+ dy

dθ

2
+ dz

dθ

2
(10)

Where
∂x
∂θ

= r + mL sinθ (11)

∂y
∂θ

= r + mL cos θ (12)

∂z
∂θ

= r + mL cot α (13)

∂s
∂θ

2
= r + mL 2 cos α2 (14)

Or
∂s
∂θ

= r + mL cosec α (15)

= r+mL
sin∝

(16)

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Olaoye et al.: Development of Multi Seeds Oil Expeller. AZOJETE,16(4):699-716. ISSN 1596-2490; e-ISSN 2545-5818,
www.azojete.com.ng

Corresponding author’s e-mail address: salthaqib@yahoo.com 704

or

S =
r+mL
sin α θ2

θ1 ∂θ� (17)

S =
r+mL
sin α

θ2 − θ1 (18)

If θ1 = 0° and α =17°, S becomes
S = 3.4203(r + mL) θ2 (19)

S = 3.4203 (r + mL) nπ

According to Stephens (2015) the screw length S is given by:-
S = 2πRn

Where:-
α is helix angle
R is radius of shaft screw
n is number of pitch thread
The volume of the spiral space between the crest of the screw and the inside of the barrel was
found from:

V = M
ρm3ℎ−1

(20)

reported that the input capacity per hour of the screw press can be found by using capacity:
C = 60 PANKmKnρ (21)

Where:-
Km is 0.35
Kn is 1.0
P is pressure
A is cross-sectional area
ρ is density of fluid
N is speed of the screw pitch
With N being varied between 46.6 and 92.0 rpm for screw pitches of 100 mm and ρ is 620
kgm3, i.e.

V = M
ρ
= 10

620
m3

ℎ (22)

Hence: V = 2.6882 × 10−4 = m3
ℎ (Oyinlola et al., 2004)

V = BSH = nπ2D2ℎtan∝ sec∝ = 2.6882 × 10−4m3

If h =5 mm, D = 38 mm, α = 17° from which n = 12 approximately.
Therefore the screw length as given by equation 3.16 equals
S = 3.4203(r + mL)(nπ) = 2.45 m.
= (r +mL)2Cos2
Or

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Arid Zone Journal of Engineering, Technology and Environment, December, 2020; Vol. 16(4):699-716. ISSN 1596-2490; e-ISSN 2545-
5818; www.azojete.com.ng

Corresponding author’s e-mail address: salthaqib@yahoo.com 705

∂s
∂θ

= r + mL cos α =
r+mL
sin α

(23)

If θ1 = 00 and  = 450
S = 1.4142 (r + mL) θ2 (24)
S = 1.4142 (r + mL) n (25)
n = 0.6789
The pitch of the screw thread will be determined by considering the handling capacity of the
screw press and the difference between the volumes of the untapered and the tapered end of
the expelling section (Figure 4)

VH =(VU - VT ) P (26)

Where
P is pitch of screw thread.
VH is handing capacity of the screw press
VU is capacity of the untapered end of the cone
VT is capacity of the tapered end of the cone

(i) The screw thread length = 0.5504 m
(ii) The desired range of speed for the screw press is 30 to 60 revolutions per minute (rpm).
(iii) An integral cone of 40 mm inner diameter, 87 mm outer and 800 mm length was
incorporated in the press.
(iv) In one revolution of the screw, the output is advanced by one pitch of the thread.
(v) The handling (design) capacity of the screw press as obtained from Equation 20 is given as
8.64 x 10-4m3

Using equation 19, the pitch of the thread was calculated thus:
VH = 8.64 x 10 x 10-4m3

VU =
π 0.12 p

4
(27)

= 11.31 x 10-3P m3

VT =
π 0.04 p

4

=1.32 x 10-3P m3

Hence, 8.64 x 10-4 m3 = (11.31-1.32) x 10-3P m3

P = 8.64 × 10−4

11.31−1.32 ×10−3
(28)

P = 0.0864 m
P = 86 mm

Efficiency of tℎe macℎine = Mecℎanical advantage ×100%
Velocity ratio (29)

Velocity ratio = 2π ×distance moved by effort
pitch (30)

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Olaoye et al.: Development of Multi Seeds Oil Expeller. AZOJETE,16(4):699-716. ISSN 1596-2490; e-ISSN 2545-5818,
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Corresponding author’s e-mail address: salthaqib@yahoo.com 706

From equation 24, efficiency of the machine can Increase by a decrease in the velocity ratio.
This could be achieved by an increase in the pitch (equation 27). This implied that the pitch
length could be increased as from 73.75 mm. Pitch lengths of 90 mm was selected.

Tℎe number of tℎread n = Lengℎt of screw tℎread
pitch

(31)

Equation 3.27 will be used to calculate the number of thread if the length is constant.

v. Shaft housing
Shaft housing is cylindrical shape with outer ϕ97 mm and inner ϕ87 mm while the length is 600
mm. It was constructed from mild steel material with a hole of ϕ12 mm bore on the wall of the
shaft housing. It was designed for the screw of material as shown in Fig 4
The handling capacity of the housing was calculated thus:

Volume = πr2 × height
= 22

7
× 0.0435 × 0.0435 × 0.6

= 3.57 × 10-2 m3

The handling capacity of the housing is 3.57 × 10-2 m3

Figure 4: The expression chamber

vi. Cake and oil outlets
As shown in Figures 5 and 6, the outlets are meant for the collections of the cake and the oil,
respectively.

vii. The standing frame
The standing frame is made up of angle iron 75 × 75 × 5 mm in cross-section. The frame is
1363 mm in length, 900 mm width and 475 mm in height. Other component parts of the
machine such as differential unit, the expelling unit, hopper, front yoke, pulley and V-belt were
mounted on it. The frame was designed to take care of the vibration and the alignment
between the pulley on the electric motor and the differential (Fig 7).

2.2. Materials
The materials used for the project can be grouped into materials for machine fabrication,
instrumentation material and oilseed materials (palm kernel, groundnut kernel and soya seed).

2.2.1. Materials for machine fabrication
The materials used in fabricating the multi-purpose oil expeller include angle bar (75 mm) -
construction of the machine frame, stainless steel plate (1.5 mm) - for the construction of
screw, press, cylindrical pipe (87 mm) - for the shaft housing, Rod (ϕ 40 mm), pulley and belt

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set - for driven and transmission of power, universal joint/front yoke – for connection of the
worm shaft and final drive shaft, electric motor (15 hp) – for powering the machine, final drive
- for speed reduction, electrode (both ordinary and stainless) – for joining of both mild steel
and stainless materials, and paint – for preventing corrosion.

Figure 5: Cake outlet

Figure 6: Oil outlet

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Olaoye et al.: Development of Multi Seeds Oil Expeller. AZOJETE,16(4):699-716. ISSN 1596-2490; e-ISSN 2545-5818,
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Figure 7: The frame

2.1.2. Seed materials
Oil bearing materials used for the study, viz: - palm kernel, groundnut and soya bean were
collected from Ile-Ife central market and Obafemi Awolowo University Research Farm. The
seeds were subjected to various heat treatments after which they were processed with the
machine.

Sample preparation
The fresh seed was conditioned and oven- dried at different temperatures (120, 90 and 70°C)
as provided in ASAE standards (2002) to determine various moisture contents at each
temperature level. The materials were kept in desiccators to avoid being acted by the
atmosphere until it was processed with the expeller.

Moisture content determination
The ASAE S410 standard (ASAE, 2002) was used in determining the moisture content of the
three materials (palm kernel, groundnut and soya bean). The samples were heated for 25
minutes, 15minutes and 10 minutes at temperatures of 120, 90 and 70°C (ASAE, 2002) and
then kept in desiccators. A kernel sample of 1500 g was weighed into the dish and the weight
of the dish plus lid and kernel recorded. The dish and sample was transferred into an oven set
at 120, 90 and 70°C. Weight measurement was carried out at every thirty minutes until the
weight become constant for three consecutive readings. The percentage moisture content of
sample was obtained from equation 2.31.

M
w =

Wd1−Wd2
Wd2

× 100 (32)

Where:
Mw is Moisture content of sample
Wd1 is Weight of sample before drying (g)
Wd2 is Weight of sample after drying (g)

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Arid Zone Journal of Engineering, Technology and Environment, December, 2020; Vol. 16(4):699-716. ISSN 1596-2490; e-ISSN 2545-
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Dynamic viscosity determination
The dynamic viscosity of the oil extracted from the three oil seeds was determined by using
SM5001 viscometer (cup type) operation manual as reported by Owolarafe et al. (2008). The
cup was put in the circular frame and the leveling leg of the viscometer was adjusted to make
sure that the bubble on the cross frame was at the center as shown in Plate 1.
The oil extracted was poured into the flow cup and the backup was used to control the flow of
the oil. The extracted oil was allowed to flow from the flow cup to another cup and the time of
flow was taken by starting the stopwatch to test the oil appearing line shape. When the line
was cut off then the stopwatch stopped. This process was replicated thrice and the values
were recorded.

To determine the viscosity manually the following formula was used

r = t−6
0.223

(33)

where r is the dynamic viscosity (mm2/s)
t is the flow out time (s)

Plate 1: SM5001 Viscometer AMETEK Powervar Cary, NC, USA

2.1.3 Fabrication and assembly of the machine components
Figure 1 shows the three dimensional view of complete assembly of the machine components.
Assemblage of the machine began with the welding of the frames, the hopper and the electric
motor seat and the differential seat as well. The front yoke was welded to the main shaft from
the differential unit.

2.2 Performance Evaluation of the Machine
Performance evaluation of the machine was carried out by operating the machine using four
factors which include soaking time (which resulted in differential moisture content), three
variable oilseeds (palm kennel, groundnut seed and soya bean) temperature and the extraction
speed. Each of these factors was investigated using 1.5 kg of oilseed at three replicates to
determine the optimal performance of the machine. The parameters determined include oil
yield, throughput capacity and oil extraction efficiency. The effect of the processing conditions
of the oil seeds on the performance of the machine was analyzed using one way analysis of
variance (ANOVA) and Duncan’s multiple range test.

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Olaoye et al.: Development of Multi Seeds Oil Expeller. AZOJETE,16(4):699-716. ISSN 1596-2490; e-ISSN 2545-5818,
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Determination of yield of oil
The yield of oil in parentage was calculated as follows:

yoil =
Qj
Qf

(34)

Where
Qj = quantity of oil extracted in kg
Qf = quantity of oil seed processed in kg (quantity of oil extracted and the cake in kg)

Determination of throughput capacity of the machine
The capacity of the machine was calculated as shown:-
Capacity of machine (capm) = Qf

t
(35)

Where
Qf = Quantity of oilseed processed in kg.
t = Time taken in minute.

Determination of efficiency of the machine
Oil extraction efficiency (Ee) in percentage is the ratio of the weight of oil extracted to the
product of the oil (moisture content) of the oilseed and the eaglet of the product before
extraction. (Olaoye and Oyelade, 2012)

Ee = Qj x 100
X Qf

(36)

Where
Qj is quantity of oil extracted in kg.
X is the oil content (moisture content of oil) in %
Qf is total quantity of material fed into the machine in.

3. Results and Discussion
Tables 1, 2 and 3 show the data obtained on oil yield, throughput capacity and efficiency of the
machine at different conditions (moisture content and shaft speed) for the three oilseeds
processed. The average oil contents of the oilseeds were used to compute the mean values of
the efficiency of the machine. New Dungeons Multiple Range Test (DMRT) was used to
determine the differences in the mean treatment effect of moisture content on oil yield.

3.1. Effect of Shaft Speed, Moisture Content and Type of Oilseeds on Oil Yield
As shown in Table 1, increase in moisture content from 5 to 15% and increase in shaft speed
from 47.6 to 92.0 rpm increased the oil yield in all the oil seeds. At shaft speed levels of 47.6,
87.0 and 92.0 rpm, increase in the moisture content of Palm kernel oilseed increased the oil
yield from 19.0 to 23.0%, 26.0 to 48.0% and 27.0 to 51.0% respectively. With the soya bean
seed, there was no oil expelled at 5% moisture content but the oil yield later increased from
0.0 to 16.0 % as the moisture content increases for all the levels of the shaft speed as
presented in Table 2. In the case of groundnut, as the moisture content was increased from 5%
to 15%, the oil yield increased from 7.3 to 31.7%, 5.7 to 26.0% and 7.3 to 28.0% for the levels
of shaft speed as presented in Table 3. These results obtained indicated that higher oil yield can
be achieved at low shaft speed and moisture content of the seed between 5 to 10 %. These
follow the trend reported by Orhevba et al. (2013) and Samuel and Alabi (2012) though their
research work was based on neem seed.

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Arid Zone Journal of Engineering, Technology and Environment, December, 2020; Vol. 16(4):699-716. ISSN 1596-2490; e-ISSN 2545-
5818; www.azojete.com.ng

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Table 1: The mean values of Measured Parameters for Palm Kernel
Type of Oil
seed

Mean Temperature
(°C)

Mean Throughput
Capacity (Kg/h)

Mean Oil Yield
(%)

Mean Machine
Efficiency (%)

M1 S1 97.00 1.81 19.0 39.4
M1 S2 95.33 1.94 26.0 51.1
M1 S3 92.33 0.89 27.0 52.1
M2 S1 92.33 0.91 22.0 33.9
M2 S2 83.33 0.79 19.0 36.9
M2 S3 82.33 0.53 27.0 52.1
M3 S1 85.00 0.83 23.0 45.6
M3 S2 84.33 1.07 48.0 93.2
M3 S3 83.33 0.62 51.0 99.6
Legend S = Shaft speed (rpm)

M = Moisture content (%)
S1 = 47.6 rpm
M1 = 5%
S2 = 87.0 rpm
M2 = 10%
S3 = 92.0 rpm
M3 = 15%

Table 2: The mean values of Measured Parameters for Soya Bean
Type of Oil
seed

Mean Temperature
(°C)

Mean Throughput
Capacity (Kg/h)

Mean Oil Yield
(%)

Mean Machine
Efficiency (%)

M1 S1 69.67 0.00 0.00 0.00
M1 S2 68.67 0.00 0.00 0.00
M1 S3 67.67 0.00 0.00 0.00
M2 S1 69.00 0.42 12.1 62.1
M2 S2 67.00 0.57 14.5 74.4
M2 S3 66.33 0.34 11.3 57.9
M3 S1 71.67 0.52 16.0 82.1
M3 S2 69.00 0.56 16.0 82.1
M3 S3 68.67 0.52 16.0 82.1
Legend S = Shaft speed (rpm)

M = Moisture content (%)
S1 = 47.6 rpm
M1 = 5%
S2 = 87.0 rpm
M2 = 10%
S3 = 92.0 rpm
M3 = 15%

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Corresponding author’s e-mail address: salthaqib@yahoo.com 712

Table 3: The mean values of Measured Parameters for Groundnut
Type of Oil
seed

Mean Temperature
(°C)

Mean Throughput
Capacity (Kg/h)

Mean Oil Yield
(%)

Mean Machine
Efficiency (%)

M1 S1 65.0 0.09 7.3 16.7
M1 S2 66.3 0.07 5.7 15.9
M1 S3 61.7 0.09 7.3 16.7
M2 S1 68.4 0.23 18.7 42.4
M2 S2 65.0 0.31 23.3 53.1
M2 S3 60.0 0.21 17.0 38.6
M3 S1 52.4 0.55 31.7 72.0
M3 S2 46.5 0.50 26.0 59.1
M3 S3 47.7 0.57 28.0 63.6

Legend S = Shaft speed,
M = Moisture content
S1 = 47.6 rpm
M1 = 5%
S2 = 87.0 rpm
M2 = 10%
S3 = 92.0 rpm
M3 = 15%

As shown in Tables 1, increasing the machine speed from 47.6 to 92.0 at 5% moisture content
of palm kernel, caused an increase in the oil yield from 19.0 to 27.0 %, while at 10% moisture
content, increase in the shaft speed caused variation in the oil recovery ranging between 19.0
and 27.0 %, and also at 15 % moisture content, increase in the shaft speed increased the yield
from 23.0 to 51.0%. In the case of soya bean, at 5% moisture content, there was no oil expelled
for all the levels of the shaft speed, and also at 10 % moisture content, the increase in the shaft
speed varied the yield ranging between 11.3 and 14.5 %, while at 15 % moisture content, the
yield was constant at 16 % for all the levels of shaft speed as presented in Table 2. This implies
that moisture content of at least 10 % is required for oil extraction from soya bean. In the case
of groundnut, at 5, 10 and 15% moisture content, increase in the shaft speed resulted to
variation in the yield which ranged between 5.7 and 7.3%, 17.0 and 23.3%, also 26.0 and 31.7%
as shown in Table 3. This observed pattern in the oil yield for the seeds being considered could
happen as a result of the heat effect which helps in better rupture of the cell walls and globules
which helped in easy oozing out of the hull. This trend was reported by Shukla et al. (1992).

3.2. Effect of Shaft Speed, Moisture Content and Seed Type on Machine Efficiency
As presented in Table 1, the efficiency of the machine when used in processing palm kernel
increases with increase in moisture content and machine shaft speed. The machine reaches its
optimum performance in terms of efficiency (99.6 %) when processing palm kernel at 15 %
moisture content and machine speed of 92.0 rpm. For soya bean, 0% machine efficiency was
obtained at moisture content below 10%, while the highest machine efficiency (82.1%) was
obtained at 15% moisture content for all levels of the machine speed. Groundnut requires a
low level of shaft speed and high moisture content to obtain the best machine efficiency.
Highest machine efficiency of 72.0% was obtained at 5% moisture content and 47.6 rpm shaft
speed. The lower machine speed increases the heat effect on the seeds which helps in better
rupture of the cell walls and globules which helped in easy oozing out of the hull. This result is
corroborated by the findings of Jimoh and Olukunle (2013); Orhevba et al. (2013); Ashaolu and
Noibi (2013). The variation in terms of the optimum performance of the machine is as a result
of the difference in properties of the seeds considered in the study.

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Arid Zone Journal of Engineering, Technology and Environment, December, 2020; Vol. 16(4):699-716. ISSN 1596-2490; e-ISSN 2545-
5818; www.azojete.com.ng

Corresponding author’s e-mail address: salthaqib@yahoo.com 713

3.3. Effect of Processing Condition on the Throughput Capacity
The throughput capacity of the machine varies with moisture content of the seed and machine
speed. For palm kernel, the highest throughput capacity (1.94 kg/h) was obtained at 5%
moisture content and machine speed of 87.0 rpm. As presented in Table 1, there was variation
in the throughput capacity obtained at different levels of moisture content and shaft speed This
variation may be as a result of the oilseed compressive strength and shearing force in the palm
kernel. This follows the trend recorded by Omoruyi and Ugwu (2013).

The throughput capacity of soya bean at 5 % moisture content was 0.0 kg/h for all the levels of
shaft speed, while throughput capacity of 0.42, 0.57 and 0.34 kg /h was obtained at 10 %
moisture content for the 3 levels of the shaft speed. Also, at 15 % moisture content, the
throughput capacity values were 0.52, 0.56 and 0.52 kg/hr for the 3 levels of the shaft speed
(47.6, 87.0 and 92.0 rpm) respectively as shown in Table 2. The highest throughput capacity of
soyabean was obtained at 10% moisture content and 87.0 rpm machine speed.

In the case of groundnut, the throughput value at 5 % moisture content was 0.09, 0.07 and 0.09
kg/h for the 3 levels of shaft speed, while throughput capacity of 0.23, 0.31 and 0.21 kg/h was
obtained at 10 % moisture content, 0.55, 0.50 and 0.57 kg/h was also obtained at 15 % moisture
contents for the 3 levels of the shaft speed (47.6, 87.0 and 92.0 rpm) respectively as shown in
Table 2. Higher moisture content causes plasticizing effect which reduces the level of
compression (Shukla et al, .1992). Similarly, heat generated by the wormshaft during pressing
can be fully transferred to the individual fat globules, which result in breakdown of the emulsion
form of the fat and help in releasing more oil droplets. Olayanju et al. (2006)

3.4. Effect Processing Conditions on Volumetric Flow Rate of the Oil
The processing condition such as type of oil seed, moisture content and shaft speed on
volumetric flow rate was discussed in this section.

In Table 4, it could be observed that the volumetric flow rate of palm kernel ranges from 0.7 ×
10-6 to 1.77 × 10-6 m3s-1, the highest volumetric flow rate was observed at 5% moisture content
and 92.0 rpm shaft speed. In the case of soya bean, the volumetric flow rate is between 1.31 ×
10-7 m3s-1 to 2.95 × 10-7 m3s-1, the volumetric flow rate reached its peak value 15 % moisture
content and 92.0 rpm shaft speed. Similarly, the volumetric flow rate of groundnut ranges
between 0.34 × 10-6 to 0.84 × 10-6 m3s-1, and reaches the maximum level at 5 % moisture
content and 87.0 rpm shaft speed as shown in Table 4. This indicates that, the highest
volumetric flow rate was observed in palm kernel while the lowest volumetric flow rate was
observed in soya beans. Samuel and Alabi (2012), corroborated the findings stating that at
constant temperature, excessive increment in moisture content of kernel seeds could reduce
the expulsion ability and wear of mechanical parts of expeller.

From Table 4, it could be observed that increase in the moisture content from 5 to 15 % while
the shaft speed is kept constant at 47.6 rpm, the volumetric flow rate of palm kernel fluctuate
between 0.90 × 10-6, 0.70 × 10-6 and 0.85 x 10-6 m3s-1. Also at 87.0 rpm, increase in the
moisture content as stated caused the volumetric flow rate to also fluctuate between 1.22x10-6,
1.21 x 10-6 and 1.17 x 10-6 m3s-1. While maintaining a shaft speed of 92.0 rpm and increase in
the moisture content, the volumetric flow rate decreases from 1.77 x 10-6 to 1.73 x 10-6 m3s-1.
This trend was also reported by Ezeoha et al (2017). Similar trend was also observed in the
case of soya bean and groundnut and which was corroborated by the findings of Rouhollah and
Seyyed, (2016).

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Olaoye et al.: Development of Multi Seeds Oil Expeller. AZOJETE,16(4):699-716. ISSN 1596-2490; e-ISSN 2545-5818,
www.azojete.com.ng

Corresponding author’s e-mail address: salthaqib@yahoo.com 714

Table 4: Processing condition of the volumetric flow rate of oil
Type of oilseed Shaft speed (rpm) Moisture content (%) Volumetric flow Rate (m3/s)

47.6 5 0.90 x 10-6

Palm Kernel 47.6 10 0.70 x 10-6

47.6 15 0.85 x 10-6

87.0 5 1.22 x 10-6

Palm Kernel 87.0 10 1.21 x 10-6

87.0 15 1.17 x 10-6

92.0 5 1.77 x 10-6

Palm Kernel 92.0 10 1.74 x 10-6

92.0 15 1.73 x 10-6

47.6 5 1.31 x 10-7

Soya Bean 47.6 10 1.36 x 10-7

47.6 15 1.43 x 10-7

87.0 5 1.78 x 10-7

Soya Bean 87.0 10 1.75 x 10-7

87.0 15 1.81 x 10-7

Soya Bean
92.0
92.0
92.0

5
10
15

1.91 x 10-7
1.93 x 10-7
2.95 x 10-7

47.6 5 0.61 x 10-6

47.6 10 0.58 x 10-6

Groundnut 47.6 15 0.34 x 10-6

87.0 5 0.84 x 10-6

87.0 10 0.67 x 10-6

Groundnut 87.0 15 0.70 x 10-6

92.0
92.0

5
10

0.70 x 10-6
0.67 x 10-6

92.0 15 0.66 x 10-6

4. Conclusion
Development of a machine to extract oil from different classifications of oil seeds (hard or soft)
is possible provided the properties of the seeds are carefully considered at the design stage.
The effect of processing conditions such as the moisture content of the seeds and shaft speed
of the machine on properties such as the oil yield, throughput capacity and efficiency of the
machine was examined. The study revealed that optimum performance of the machine in terms
of oil yield for all the seeds (hard or soft) occurs at 15% moisture content of seed and 47.6
rpm machine speed. Volumetric flow rate of oil from the seeds is directly influenced by the
shaft speed, moisture content and oil temperature. The highest efficiency of the machine will be
attained at low shaft speed and moisture content of the seeds ranges between 5 to 10%. In
general, the data presented in the study will be useful in optimizing the mechanics of mechanical
oil extraction using the multi-seed oil expeller.

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Arid Zone Journal of Engineering, Technology and Environment, December, 2020; Vol. 16(4):699-716. ISSN 1596-2490; e-ISSN 2545-
5818; www.azojete.com.ng

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www.azojete.com.ng

Corresponding author’s e-mail address: salthaqib@yahoo.com 716

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