Physical Properties of Sunflower Seeds Components · PDF filePhysical Properties of Sunflower Seeds ... character on which the separation process will be based. ... To identify the

International Journal of Engineering & Technology IJET-IJENS Vol:13 No:01 103

I J E N S IJENS © February 2013 IJENS -IJET-4747-0124131

Physical Properties of Sunflower Seeds

Components Related to Kernel Pneumatic

Separation Gamal Rashad Gamea

Agricultural Engineering Department, Faculty of Agriculture, Minoufiya University, egypt gamea@[email protected]

Abstract-- The first part of the present study deals with some

physical properties for sunflower seeds components (seeds,

hulls and kernels) related to pneumatic separation which are

evaluated as a function of change in moisture content from 8% to 14% (d.b.). S imple linear empirical equations were

developed to predict sunflower seeds components properties

according to moisture content. All dimensions, mass, angle of

repose, coefficient of fraction, and terminal velocity increased

linearly with the moisture content increased up to 14 %, while the bulk density decreased linearly with the moisture content

increased. The second part was carried out on a series of

experiments to specify the optimum conditions of separating

operation which ensure the highest grade of separation

efficiency with minimum kernel losses. Pneumatic separation equipment was tested under different combinations of the

following factors: air stream velocity, feed rate, broken kernels

percentage and moisture content by using indices separation

efficiency and kernel losses. The combination of air velocity ,

feed rate, broken kernels % and moisture content affected significantly the separation efficiency and kernel losses. Air

stream velocity of 3.5 m/s combined with 30 kg/h feed rate,

10% broken kernels and (10 – 12%) moisture content can be

considered the most favorable combination values.

Index Term-- sunflower kernels, pneumatic separation,

terminal velocity, kernel losses

Nomenclature

L length, mm

W width, mm

T thickness, mm

Gd geometric diameter, mm

Ad arithmetic diameter,mm

Fs Surface flat area, mm2

Ts Transverse flat area, mm2

Db bulk densit, g/cm

m mass of seeds or kernels, g

Cd drage coefficient

ρa air density, kg/m3

V air terminal velocity, m/s

A particle area projected to air, m2

S.E Separating efficiency, %

M1 the mass of hulls in the out kernel tank, g

M2 the mass of hulls in feeding hopper, g

K.L Percentage of Kernel losses, %;

M3 the mass of kernel in the out kernel tank, g;

M4 The mass of kernel in feeding hopper, g.

M.C. moisture content(d.b.), %

1. INTRODUCTION

Sunflower seed ( Helianthus annuus L.) is an important

oilseed crop because it contains a large quantity of highly

nutritious oil. Sunflower considered as one of the most

Egyptian leading oilseed crops; it could be planted in

several soil types under varied climate condition. Allen et

al., (1983) reported that, sunflower is the second most

important source of vegetable oil in the world, it followed

soybean crop. Sunflower was developed as the primary

oilseed crop in the Russia and has been widely accepted in

Europe, Argentina, and Australia, since 1966. Oilseed of

sunflower became an important economic crop in the United

States and Canada

The oil production in Egypt has a great problem due to

the high gap between production and consumption. The

production of both cotton and soybean crops, which

considered the main source of oil, affect oil production.

Therefore, the direction toward untraditional oil crops such

as sunflower seeds becomes more intended.(Morsy, 1980).

Sunflower kernels can be used for preparation of many

production like tosta bread, tahina ,halawa, and

confectionery items. EL-Shaer et al., (1993) mentioned that,

sunflower seeds contained approximately 30 % hull and

70% Kernels. The hulls contain the high fiber, low protein

and high wax and only 2 - 3 % oil. Large proportion of oil is

retained by the high percentage of hull of oil seeds. If the

hulls are removed from the seed before processing, it would

yield comparatively more volume of oil, decrease the

production cost of edible oil and consequently increase the

rate production of oil because removing of the hull from

seeds decreased the mass of the used seeds.

Hulling is a process of removing hulls from the oil

bearing seeds for obtaining high quality edible oil by the

processing of kernels. This reduces fibrous content of the

meal and increases the marketability as stock feed. About

99% of oil is stored naturally in kernels and the hulls

contain not more than 1% oil. If the hulls are not removed

they reduce the total yield of oil by absorbing or retaining

oil in the pressed cake. In addition to this the wax and

coloring matters present in the hulls get mixed with the

expressed edible oil. This necessitated the refining process,

and therefore, increases the production cost of edible oil.

Moreover, processing oilseeds without dehulling reduces the

capacity of the extraction equipment in addition to more

repair and maintenance costs. A large proportion of oil is

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I J E N SIJENS © February 2013 IJENS -IJET-4747-0124131

retained by the high percentage of hull of oilseeds. If the

hulls are removed from the seed before processing, it would

yield comparatively more volume of oil (Canada, 1998).

After hulling of sunflower seeds, it is necessary to remove

the separate hulls, therefore separating machine is needed.

The separation of sunflower kernels from a hulled mixture is

very difficult due to the slight difference of the properties of

the mixture components and the lack of information about

the methods of separation of this product.

To the best of our knowledge, there is no evidence on the

physical properties of sunflower seeds components. Thus to

design equipment to improve the existing processing

method, the physical properties of the seed components has

to be known.

Dimensions are important to design the cleaning, sizing

and grading machines. Bulk density, kernel density and

porosity are major considerations in designing the drying,

aeration and storage systems, as these properties affect the

resistance to air flow through the grain mass. Angle of

repose and coefficient of friction are important in designing

equipment for solid flow and storage structures. The

coefficient of friction between seed and wall is important

parameter in the prediction of seed pressure on walls .

(Caumble and Maina, 1990)

El-Kadi and El-Shazly (1970) reported that, before

choosing the method of separation, there must be clear

difference between the compounds of the mixture at the

character on which the separation process will be based. The

process of separation impurities and strange grains occurs

according to engineering and natural characteristics of

compounds.

Clark et a1., (1980) mentioned that, removal of

sunflower hulls from kernels by aspiration has only limited

application because sunflower seed kernels are too easily

picked up along with hulls. Some other principle of

separation was needed, and specific gravity separation might

be selected.

Khairy and Al-Nakib (1989) reported that, the method of

separation was limited by the existence of the difference

between the physical characteristics of mixture components.

Many systems are used in separating seeds and grain,

they consists of one or more of the following units: screen

unit, disc and cylinder separators, spiral separator,

centrifugal separator, cyclone separator, and pneumatic

separator.

In handling and processing of several agricultural

products, air is commonly used as a carrier for transport

(kilickan and Guner, 2006) or for separating the desirable

products from unwanted materials (Khoshtaghaza and

Mehdizadeh, 2006).

In pneumatic separators, air is used for separation of

products according to its differences in size, shape, density,

and characteristics of surface air resistance. Air is supplied

by a centrifugal fan with an adjustable inlet for controlling

the flow. Air is moved through a chamber into which the

product to be cleaned or separated. Materials not carried by

the air stream drops on to a tray and removed. While the

material carried by the air stream is lifted to an air separator

from which it is removed from the system. This unit can be

used for separation of dry or wet materials. Successful

operation depends upon proper adjustment of airflow and

uniform feeding of the product into the air stream.

Therefore, the knowledge of terminal velocities of grain and

impurity particles becomes essential for design and

operation of pneumatic devices. Testa et al., (1967) reported

that, the cleaning efficiency of the pneumatic separator

affected by pneumatic separator design, air stream velocity,

unit load of feeding material, feeding material components,

dimension of separating duct, uniformity of air stream

velocity and initial velocity of mixture.

El-Sheikha et al., (1988) studied the effect of horizontal

air stream velocity, total impurity, and different proportion

of chaff and straw on separation efficiency at different

feeding rates. Gamea , (2004) mentioned that, using the air

as method of separating of rap-seed considered efficient to

obtain satisfactory values of separation efficiency with

minimum losses. Amer, (2009) Concluded that, the physical

and aerodynamic properties of flaxseeds were expressed by

the linear regression equations as a function of moisture

content. Ilori et al, (2011) studied physical properties of

Mexican sunflower seed.

Gupta et al., (2007) evaluated the terminal velocity of

sunflower seeds of three cultivars namely NSFH-36, PSF-

118 and SH-3322 as a function of moisture content and

concluded that the variation in moisture content as well as

variety either individually or in combination influences

terminal velocity and drage coefficient significantly. Their

results showed that, in the moisture range from 6% to 14%

d.b. , the terminal velocity of the seeds increased from 2.039

to 3.28, 2.54 to 3.04 and 2.98 to 3.53 m/s respectively for

the above varieties.

The main objectives of the present study may be

summarized as follows:

1. To identify the physical-mechanical properties of

sunflower product components (seeds, hulls and kernels)

and it is correlation with change in moisture content to

predict the air velocity required for separation of kernel

from hulls.

2. To carry out a series of experiments to specify the

optimum conditions of separating process, which ensure the

highest grade of separating efficiency with lowest kernel

loss.

2. MATERIALS AND METHODS

2.1. Materials

Sample of the sunflower seeds (Vidoc variety) were

taken from Oil Crops Institute, Ministry of Agriculture, and

have been used in this study. The sunflower seeds were

cleaned manually from (foreign matter, broken and

immature seeds) and stored in tightly sealed bin. Sunflower

seeds were hulled by a prototype for sunflower seeds hulling

designed and manufactured at the Agricultural Engineering

workshop, Faculty of Agriculture, El-Minoufiya University

by Gamea and Mohamed (2011). Components of hulled

product (full kernels, broken kernels and hulls) were

separated manually. Kernels to hulls ratio was calculated as

the ratio of mass of dry kernels to the mass of dry hulls. A

sample of 50 particles was taken randomly from every

component. The shape and size of samples were determined

by measuring the length (L), width (W), thickness (T),

geometric diameter (Gd) , arithmetic diameter (Ad), flate

surface area(Fs), transfer surface area(Ts) and

sphercity(s%). The main dimensions of seeds, kernels and



hulls (L, W, and T) under experiment were measured by

digital calipers. The following equations (El-Raie, 1988)

were used to calculate the values of the mentioned

properties:

Gd= (LWT)1/3

,mm

Ad= (L+W+T)/3,mm

Fs = π/4 LW ,mm2

Ts = π/4 TW ,mm2

S= (Gd/l) x 100, %

Masses of components were measured by sensitive

balance with an accuracy of 0.001 g.

The moisture content M.C.(d.b.) of the mixture, hulls and

kernels was determined by a low constant temperature oven

method (ASAE,2003). The method is good for species that

are rich in oil or volatile substances.

Bulk density(Db) was calculated for the seeds and kernel

of sunflower, by dividing the mass of quantity of a specific

seeds and kernels on its volume, which was measured by

using graduate cylinder.

The static friction angle for samples (seeds, kernels and

hulls) was measured against two structural materials (rough

rubber and galvanized iron).Samples were placed in the tray

over the tested surface. The tray which has the sample, was

tilted up around its side pivot, the angle of friction was

measured when 75% of the seeds reached the bottom and

the tray was stopped (Mohsenin, 1986).The calculated

friction angle for each sample with surfaces was the average

of ten replications.

Angle of natural slop (repose angle) is the angle at which

the sample, does not move when forming a cone. The

designed combined parallelogram and protractor was used

to measure the angle between the horizontal base and the

inclined side of the formed cone due to the free vertical fall

of the sample. Each experiment was repeated 10 times to

calculate the value of angle of repose for each sample.

The samples was conditioned to required moisture

content level by adding the required amount of water,

stirring occasionally and allowing it to achieve equilibrium,

then the moisture content was checked again.

The apparatus shown in fig. (1) was used to measure the

terminal velocity for suspension of different components

under study at different moisture content. It consists of a

tube constructed from transparent (plexi-glass) and

connected with the outlet of the electric blower. Two wire

screens were fitted at the bottom and top of the transparent

tube. An airflow straightened was attached with the lower

screen to improve flow uniformity through the tube. The

sample was placed on the lower screen. The terminal

velocity of the seeds, kernel and hull can be obtained by

measuring the air velocity required to suspend the particles

in the vertical air stream. When a particle is suspended into

the air stream, equilibrium is achieved between its weight

(mg) and the drag force, as follows: (Awady and El-Sayed,

1994)

mg = Cd ρa A V2

/2

2.2 Experimental procedure

The pneumatic separating equipment as sketched in

fig. (2) used in the present study was designed and

manufactured at the Agricultural Engineering Workshop,

Faculty of Agriculture, Minoufiya University, Egypt The

airflow was produced by an electric centrifugal blower of

600W and 800 r.p.m fixed on the frame. It has a circular

inlet hole of (40 mm Dia.) with a gate for controlling the

airflow rate, and has a circular outlet hole( 40 mm Dia).An

electric motor of 600W and 8000 r.p.m was used as a source

of power. The speed of the blower was changed by a simple

mechanism. The changing of air velocity was done by

changing the distance between electric centrifugal blower

and the bottom of the vertical-separating duct. Also, there

was a gate on the inlet opening for controlling the airflow

rate, consequently controls the air stream velocity through

the separating duct.

Dwyer Thermal Anemometer 470 was used to measure

the air stream velocity (ft/min) then the readings were

converted into m/s.

The galvanize smooth iron hopper was fixed to easily

feed the mixture of seeds, hulls and kernels. The hopper

had four adjustable walls to obtain the proper slope for the

mixture to slide smoothly inside the equipment. Under the

hopper There was an inclined smooth channel for receiving

the mixture from the hopper tank. The slope of channel

could be controlled by elevator to control the initial velocity

of mixture besides control the feeding rate of the mixture.

The experimental separating unit was equipped with three

screens as shown in fig. (2). The first and second were to

retain the mixture of seeds, kernels and hulls away from the

blower; while the third was to retain the impurities in

sediment chamber.



Z

1-1-Electric plower. 2-Lower wire screen. 3-Transparent tube. 4-Upper wire screen.

Fig. 1. Schematic diagram and image of the terminal velocity apparatus.

To observe the movement of mixture inside the

separating duct, the front face of the equipment was made

from plex-glass. The kernels and hulls were mixed to obtain

the different levels of the tested samples. The samples were

conditioned to the required moisture content level by adding

the required amount of water, stirring occasionally and

allowing it to achieve equilibrium, the moisture content was

checked again. The experimental separator was feed by a

mixture of seed, kernels and hulls stored in the hopper. The

mixture moved into the separating duct (150×150 mm cross

section). The proper slope of the screen causes smooth

slide movement for the mixture over the screen. The kernel

gate was laid along the screen with the same inclination to

allow slide of cleaned kernels of the screen causes smooth

slide movement for the mixture over the screen.

The kernel gate was laid along the screen with the same

inclination to allow slide of cleaned kernels. A bag was

fixed on it to receive the clean kernels. An air stream was,

directed vertically to the sample. The cleaned kernels were

collected in a bag. The hulls and foreign materials carried by

the air stream were lifted to a sediment chamber, then

collected and massed. The kernels which were separated

with the light particles was then separated manually and

weighed to calculate the separation efficiency and kernel

losses percentage.

The main tested factors for separating unit were

moisture content of mixture, percentage of the broken

kernels, velocity of air stream and feeding rate of

mixture.

15cm

70 cm

4 cm 1

4

3

2



1- Centrifugal blower. 2- Feeding hopper. 3- Vertical separating duct.

4- First screen. 5- Kernel gate. 6- Frame. 7- Sediment chamber. 8- Feeding gate. 9- Second screen. Dims: cm

Fig. 2. Elevation view of the separating equipment.

Their effect on separating efficiency and kernel

losses percentage was carried out individually at the

following levels:

Three different levels of mixture moisture content (d.b.)

(8, 10, 12and 14 %).

1- Three different quantities of broken kernel in sample

(10, 20 and 30 %).

2- Three different velocities of air stream (3, 3.5 and 4

m/sec).

3- Two different feeding rates (30 and 50 kg/h).

Each measurement was replicated three times thus, the

number of compound variables were 72 while the total

number of tests were 216.

The performance of the separating unit was evaluated

from the point of view of separating efficiency and

percentage of kernel losses.

The used formula for calculating the separating

efficiency was suggested by (Ismail et al, 1994) as follow:

S.E % = (M2 – M1)/M2 × 100 %

The percentage of kernel losses was calculated by the

following formula (Ismail et al, 1994) :

K.L% = (M4- M3)/M4 × 100 %

The analysis of variance test (ANOVA) was used to test

the effect of the experimented independent variables on

separation efficiency and kernels losses percentage.

3. RESULTS AND DISCUSSIONS

3.1. physical properties of seeds, hulls and kennels

Linear dimensions:

The variations of length (L), width (D), thickness (T) and

the geometric mean diameter (Gd ) of the seeds , hulls and

kennels with moisture content are plotted in fig.s (3a), (3b)

and (3c).

9

1

8



0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

7% 9% 11% 13% 15%

Dim

ensi

ons,

mm

.

Moisture content, % (d.b).

L W T GD

Fig. 3a. Effect of moisture content on dimensions of sunflower seeds.

All the dimensions were increased with moisture content

up to about 14%. The total average expanded was moving

along its minor axis in comparison with its other two

principal axes. This behavior was also observed by

dehspande (1993).

The relationships between principal dimensions (L, W, T

and Gd ) and its moisture content represented as follow:

For seeds:

0.00

2.00

4.00

6.00

8.00

10.00

12.00

7% 9% 11% 13% 15%

Dim

ensi

ons,

mm

.


L W T GD

Fig. 3b. Effect of moisture content on dimensions of sunflower hulls.

L = 7.45M.C. + 11.948 R2 = 0.95

W = 1.8M.C. + 5.712 R2 = 0.98

T = 4.8M.C. + 3.337 R2 = 0.73

Gd = 4.76M.C. + 6. 11 R2 = 0.85

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

7% 9% 11% 13% 15%

Dim

en

sio

ns,

mm

.


L W T GD

Fig. 3c. Effect of moisture content on dimensions of sunflower kernels.

For hulls:

L = 1.1M.C. + 9.884 R2 = 0.84

W = 1.6M.C. + 4.104 R2 = 0.91

T = 1.65M.C. + 0.676 R2 = 0.96

Gd = 2.68M.C. + 3.03 R2 = 0.96

For kennels:

W = 1.4M.C. + 3.526 R2 = 0.78

L = 1.7M.C. + 6.808 R2 = 0.95

T = 1.15M.C. + 1.131 R2 = 0.99

Gd = 1.76M.c. + 300 R2 = 0.94

The results showed that the relationship between

dimensional characteristics and moisture content of the

studied samples suggested in trend with the results of

Matouk ,2004and amer ,2009

Sphericity:

The values of spheicity for sunflower seed components were

calculated individually by equation mentioned above, by

using data or geometric diameter and major axis of the

sample and the results obtained are presented in fig. (4). The

relation between M.C and sphericity % is linear and

represented by the following regression equation:

Ss = 19.7 M.C. + 49.648 R2

= 0.84

Sh = 24.7 M.C. + 30.428 R2 = 0.9

Sk = 14.4 M.C. + 43.93 R2 = 0.86

Flat and transfer surface area:

Variation of samples surface area with seed moisture content

is shown in fig (5a) and (5b). The surface area of both

transfer and flat were increased with moisture content up to

about 14%.

And the following equations represents the relation between

flat and transfer area and M.C for seeds, hulls, and kennels.



20

25

30

35

40

45

50

55

7% 9% 11% 13% 15%

Sp

hercit

y,%

Moisure Content, % (d.b.)

seeds hulls kernels

Fig. 4. Effect of moisture content on sphercity for sun flower seeds, hulls

and kernels.

10

20

30

40

50

60

70

7% 9% 11% 13% 15%

Fla

t S

urfa

ce a

rea

, m

m2

Moisture Content, % (d.b.)

seeds hulls kernels

Fig. 5a. Effect of moisture content on flat surface area for sunflower seeds,

hulls and kernels.

Tss = 27.7 M.C. + 14.888 R2 = 0.795

Tsh = 6.55 M.C. + 2.16 R2 = 0.95

Tsk = 4.85 M.C. + 3.09 R2 = 0.95

Fss = 52.25 M.C. + 53.495 R2 = 0.97

Fsh = 16.15 M.C. + 31.841 R2 = 0.97

Fsk = 12.4 M.C. + 18.546 R2 = 0.88

0

5

10

15

20

7% 9% 11% 13% 15%

Tra

nsfer a

rea

, m

m2

Moisture Content, % (d.b.)

seeds hulls kernels

Fig. 5b. Effect of moisture content on transfer surface area for sunflower

seeds, hulls and kernels.

Thousand piece mass

The measurements of thousand piece of different

components with different M.C are displayed in fig (6).

Mass of components increased linearly with increasing

moisture content of sunflower components.

The relationship between mass of 1000 pieces and M.C may

be represented by the following equations:

Ms = 240 M.C. + 64.6 R2

= 0.91

Mh = 115 M.C. + 8.6 R2

= 0.988

Mk = 115M.C. + 56.6 R2

= 0.988

0

20

40

60

80

100

120

7% 9% 11% 13% 15%

Ma

ss o

f 1

00

0p

ea

ce, g

Moisure Content, % (d.b.)

Seeds Hull Kerenl

Fig. 6. Effect of moisture content on mass of thousands piece for sunflower


Bulk density

The experimental results of the bulk density for seeds,

hulls and kernels at different moisture levels are ploted in

fig. 7. As the moisture content increased from 8 to 10 %

(d.b.), the bulk density decreased from 450.45 to 408.2,

from240.4 to 212.3 and from 690.6 to 615.1 kg/m3

for seeds,

hulls and kernels respectively.

Fig. 7. Effect of moisture content on bulk density for sunflowers seeds,

hulls and kernels.

The following linear regression equations described the

relationship between bulk density and moisture content

(d.b):

Bds = -680M.C. + 501.8 R2 = 0.98

Bdh = -115M.C. + 8.6 R2 = 0.99

Bdk = -115M.C. + 56.6 R2 = 0.99



Angle of repose:

The experimental results for the angle of repose of the

seeds, hulls, and kennels at various moisture levels are

shown in fig. 8.

The relationship between angle of repose and moisture

content could be represented by the following equation:

For seeds:

RAs = 74M.C. + 23.66 R2 = 1.00

For hulls:

RAk = 61.5M.C. + 19.96 R2 = 0.99

For kernels:

RAh = 113M.C. + 27.42 R2 = 0.95

A linear increase in angle of repose when the material

moisture content increases has also been noted for sun

flower seeds by cupta ,1997.

The mean value of angle of repose for. The mixture of

hulls and kennels were 31.0 , 32.8 , 34.5 and 35.8 for

mixture moisture content 8,10,12 and 14% respectively.

Static coefficient of fraction

The effect of moisture content of seeds, hulls and kennels

and the static coefficient of friction against galvanize iron is

plotted in fig. 9.

The static coefficient of friction increased also linearly

with respect to moisture content up to 14 % d.b. The

relationship between coefficient of friction and material

M.C may be represented by the following equations : C.F.s

= 1.4637M.C. + 0.2844 R2 = 0.98

C.F.k = 1.3195M.C. + 0.259 R2 = 0.99

C.F.h = 1.8843M.C. + 0.3647 R2 = 0.97

Terminal velocity

Fig. 10 represent the variation of terminal velocity with

moisture content. The fig. showed that, as moisture content

increased, the terminal velocity tend to increase linearly for

seed, hulls and kernels. Similar increasing trend was

observed for terminal velocity with increase in moisture

content for edible squash seed (Paksoy and Aydin, 2004),

for rapeseed (Calisir et, al, 2005) , for pin nut (Ozguven et

al, 2005) , for sunflower seed (Gupta et al, 2007) and for

turgenia latifolia seeds and wheat kernels(Nalbandi et al,

2010).

20.0

25.0

30.0

35.0

40.0

45.0

7% 9% 11% 13% 15%

Rep

ose

angel

, d

egre

e.

Miosture content, % (d.b)

Seeds Hull Kerenl

Fig. 8. effect of moisture content on angle of repose for sunflower seeds,

hulls and kernels.

0.3

0.35

0.4

0.45

0.5

0.55

0.6

0.65

0.7

7% 9% 11% 13% 15%

Co

effi

cien

t o

f fr

icti

on


Seeds Hull Kerenl

Fig. 9. Effect of moisture content on static coefficient of friction .

The terminal velocity was much lower for hull than that

for seed and kernel at all levels of moisture content.

However, the difference between the hull and the seed was

more than with seed and kernel. The relation between

terminal velocity and moisture content can be represented

with the following equations:

Vt.s = 24.5M.C. + 2.03 R2

= 0.99

Vt.k = 31.5M.C. + 2.21 R2 = 0.92

Vt.h = 20M.C. + 0.3 R2 = 1

0.30

1.30

2.30

3.30

4.30

5.30

6.30

7.30

7% 9% 11% 13% 15%

Ter

min

al V

elo

city

, m

/s


Seeds Hull Kerenl

Fig. 10. Effect of moisture content on terminal velocity for sunflower


With the help of these results it is easy to determine the

engineering parameters for separating unit.

3.2. Evaluation of separating prototype:

The experiments were confined to different air stream

velocities ,feeding rates ,broken kennels percentage and

moisture content of mixture

The performance of the prototype was defined by the

separating efficiency % and kennels loss % .The author

aimed to determine the most favorable combination of all

these variables to be fulfilled in the adopted agricultural

mechanization procedure , so as ensure the high grade of

separating efficiency coupled with minimal kennel losses .

Fig. 11 show the relationship between the moisture content

and separation efficiency at different values of air stream

velocity (3,3.5,4 m/s), broken kennel percentage (10,20 and

30%) and feeding rate (30 and 50kg/h). Fig. 12 show the

relation between kernels losses % at different levels of all

variables.

Generally , the results showed that , separating efficiency

increased by increasing the air stream velocity . the



minimum separating efficiency was 73.8% at 3m/s air

velocity ,50kg/h feed rate, 30% broken kernel and 14%

moisture content. The maximum value of 100% was

obtained at 4.0m/s , 30kg/h , with all moisture contents and

broken kennels . At all feeding rates, it was observed that,

with increasing air stream velocity from 3 to 3.5 m/s, the

increasing rate for separation efficiency was more than the

increasing rate with increasing air stream velocity from 3.5

to 4 m/s. It may be due to that, air stream velocity 3.5m/s

was greater than the critical velocity for hulls. While, the

lowest values of separation efficiency at lowest air stream

velocities were due to the presence of some hulls with the

kernel recovered because the airflow was insufficient to

carry all the hulls out with it. On the other hand the results

showed that, kernel losses percentage increased with the

increase of air stream velocity. The highest mean percentage

of losses was 20.0 % observed at 4m/s air velocity, 8 %

moisture content, and 30kg/h feed rate. While, the lowest

mean percentage of losses was 0.0 % at 3.0 m/s air stream

velocity,10 % broken kernel and all feeding rates. At all

tested levels of feeding rates, it was observed that, at

increasing air stream velocity from 3.5 to 4 m/s, the

increasing rate for kernel losses was more than the

increasing rate if the air stream velocity changed from 3 to

3.5 m/s. This may be due to the 3.5 m/s, air stream velocity

was more than the critical velocity for hulls and broken

kernels. While, at lower value of air s tream velocity, the

airflow was too weak to carry all the hulls and kernels out.

Generally, the minimum amount of kernels losses could be

achieved at air velocity range of 3 to 3.5 m/s.

Separation efficiency decreased especially when

moisture content increased from 12 % to 14 %. But the

decreasing in separating efficiency resulting from moisture

content changed from 8 to 12 was little bit. The results

indicated that, increasing the air stream velocity increased

the percentage of kernel losses at all levels of moisture

contents. But, increasing the values of moisture content

decreased the kernel losses at 3 and 3.5 m/s air stream

velocity. However, increasing the values of moisture content

from 12 to 14% increased the kernel losses at 4 m/s air

stream velocity.

The separation efficiency decreased as the feed rate

increased from 30 to 50 kg/h. The highest value obtained at

30 kg/h and 10 % broken kernels with different levels of

other variables. The effect of feed rate was related to the

increase of the thickness of mixture layer through the

separating duct , consequently, the separation condition got

worse because of the effects the air resistance per unit

length. The data of kernels loss reveled that, by increasing

feed rate the kernels losses decreased at air velocity range of

3.5 to 4 m/s while the effect of feed rate was poor on kernels

loss at air velocity 3 m/s .

Asharp decrease in separation efficiency occurred by

increasing the broken kernel % from 20 % to 30% at

different levels of other variables while the decrease in

separation efficiency resulting from increasing of broken

kernels from 10 to 20 % was less. Also, increases of kernels

losses noticed at increase broken kernels especially at 4 m/s

air stream velocity. However the decrease of broken kernel

improved the separation efficiency and decreased kernels

loss.

The effect of the interactions among air stream velocities

and percentage of broken kernels on kernel losses were

highly significant. The highest percentage of kernel losses

(20%) was at the interaction of 4 m/s air stream velocity and

30% broken kernels. While, the lowest percentage (0.0 %)

was at 3 m/s air stream velocity and 10% broken kernels.

Feed rate 30 Kg/hr

70

75

80

85

90

95

100

105

110

7% 8% 9% 10% 11% 12% 13% 14% 15%

Sep

ara

tio

n E

ffic

ien

cy

, %

Moisure content. % (d.b.)

3 m/s 3.5 m/s 4 m/s

70

75

80

85

90

95

100

105

110

7% 8% 9% 10% 11% 12% 13% 14% 15%

Sep

ara

tio

n E

ffic

ien

cy

, %

Moisture content, % (d.b)

3 m/s 3.5 m/s 4 m/s

10 % B.K

20 % B.K

30 % B.K



4. CONCLUSION

1- The physical properties of sunflower seeds, hulls

and kernels varies linearly with moisture content

2- The average terminal velocity for sunflower seeds

was 4, 4.5, 4.9 and 5.5 m/s, for sunflower hulls

1.9, 2.3, 2.7 and 3.1 m/s and for sunflower kernels

was 5.4, 5.7, 6.1 and 6.5 m/s at moisture content

8, 10, 12 and 14 % (d.b.) respectively

3- The air stream velocity was a major controlling

factor that affects the separating efficiency and

kernel losses. The air stream velocity, which

fulfilled the best results was 3.5 m/s.

4- The decrease of broken kernels percentage

improved the separation efficiency and kernel

losses

5- Increasing of moisture content (from 12to 14%)

decreased the separating efficiency. But

increasing moisture content (from 10to 12%) the

decreasing of separating efficiency is very small.

6- Air stream velocity of 3.5 m/s combined with 30

kg/h feed rate, 10% broken kernels and ( 10 –

12% ) moisture content can be considered the most

favorable combination values of these variables to

obtain the highest separation efficiency with

minimum kernel losses.

7- Using the air as the method of separating of

sunflower kernel considered efficient to obtain

satisfactory values of separation efficiency with

minimum kernel losses at suitable levels of feed

rate, broken kernels and moisture content.

8- The separation equipment succeeded for purpose

as astep forward to the complete design coupled

with hulling machine for optimal hulling and

separation machine.

Feed rate 50 Kg/hr

70

75

80

85

90

95

100

105

110

7% 8% 9% 10% 11% 12% 13% 14% 15%

Sep

ara

tio

n E

ficen

cy

, %


3 m/s 3.5 m/s 4 m/s

70

75

80

85

90

95

100

105

110

7% 8% 9% 10% 11% 12% 13% 14% 15%

Sep

ara

tio

n E

ffic

en

cy

, %

Moisutre content, % (d.b.)

3 m/s 3.5 m/s 4 m/s

70

75

80

85

90

95

100

105

110

7% 8% 9% 10% 11% 12% 13% 14% 15%

Sep

ara

tio

n E

ffic

en

cy

, %


3 m/s 3.5 m/s 4 m/s

Fig. 11. Effect of moisture content on separation efficiency at differen t levels of air stream velocity, broken kernels and feed rate.

10 % B.K

20 % B.K

30 % B.K



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0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

7% 8% 9% 10% 11% 12% 13% 14% 15%

Kern

el

Lo

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0

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7% 8% 9% 10% 11% 12% 13% 14% 15%

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18.0

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7% 8% 9% 10% 11% 12% 13% 14% 15%

Kern

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Lo

sses,

%


3 m/s 3.5 m/s 4 m/s

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

7% 9% 11% 13% 15%

Kern

el

Lo

sses,

%


3 m/s 3.5 m/s 4 m/s

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

7% 8% 9% 10% 11% 12% 13% 14% 15%

Kern

el

Lo

sses,

%


3 m/s 3.5 m/s 4 m/s

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

7% 8% 9% 10% 11% 12% 13% 14% 15%

Kern

el

Lo

sses,

%


3 m/s 3.5 m/s 4 m/s

Fig. 12. Effect of moisture content on kernel losses (%) at different levels of air stream velocity, broken kernels and feed rate.

10 % B.K 10 % B.K

20 % B.K 20 % B.K

30 % B.K 30 % B.K



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