Important Engineering properties of Cereals, Pulses and Oilseed and there use in processing equipment.

1. Subject
Protected Cultivation and Secondary
Agriculture
Topic
Important Engineering Properties of
Cereals, Pulses and Oilseed
by
Dr. Sanjay Singh Chouhan
Assistant Professor
College of Agriculture, JNKVV,
Powarkheda, Hoshangabad
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2. Importance of Engineering Properties
Biological materials especially that are consumed as food or feed undergo various unit
operations like
• Pre-harvest to post harvest processing
• primary, secondary and tertiary processing,
• preservation,
• packaging and storage
• distribution,
• retailing,
• domestic storage and finally consumption.
Scientists and engineers need to know and understand the characteristics of the
material for designing and selecting such tools and equipment require information
regarding various properties.
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3. Important Engineering Properties
Physical properties:
Shape, Size, Volume, Surface area, Density, Specific gravity and
Porosity
Mechanical properties:
Hardness, Compressive strength, Impact & Shear Resistance and
Rheology
Thermal properties:
Specific heat, Thermal conductivity, Thermal Diffusivity, Enthalpy
and Emissivity
Aero and Hydrodynamic properties:
Terminal velocity and Drag coefficient
Frictional properties:
Angle of repose, Coefficient of friction, Rolling resistance
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4. Application of Various Engineering Properties
• Physical properties like size, shape, density, porosity has great implication in deciding
the equipment for screening, separation, handling and storage of materials, they also
come handy in calculating the heat transfer and mass diffusion rates.
• Frictional properties are useful in designing discharge and conveying devices.
• Aerodynamic and hydrodynamic properties are useful in designing spouted bed,
fluidized bed dryers, aspirators and pneumatic conveying system.
• Knowledge of thermal properties aids in designing thermal process and calculating
thermal load for canning, retorting, sterilization, pasteurization, blanching, cooking and
extrusion process.
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5. • Electric properties can be useful in designing and controlling thermal
processing and moisture content determination.
• Dielectric properties of the food strongly influenced the degree of heating of a
food material subjected to microwave or radio frequency processing.
• Rheological behavior under limited deformation has been widely used to
obtain information on the structure and viscoelasticity of materials.
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6. ➢Shape
➢Size
➢Volume
➢Surface area
➢Density
➢Porosity
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Physical
Properties

7. • Size is an important physical attribute of foods used in
screening solids to separate foreign materials, grading
of fruits and vegetables, and evaluating the quality of
food materials.
• In fluid flow, and heat and mass transfer calculations, it
is necessary to know the size of the sample.
• Size of the particulate foods is also critical as it affects
the viscosity and dispersibility and stability of the
product
• It allows the sorting of fresh market various agro-
produces into size groups. This is helps in assigning
market and price differentials of large and small
produce, to match consumer preferences and to allow
pattern packing. 7
SIZE

8. • Size determination is mandatory for modern or on-line fruit/ vegetables/
grain/spices density sorting, for which two size-related parameters, volume and
weight, are required.
• Grading of agro-produce into size groups is often necessary in the food industry, to
meet the requirements of some primary and secondary processing machines.
Methods of measurement of size:
• Projected area method
• Micrometer measurement (Vernier caliper, Micrometer)
• Electronic system (Digital imaging)
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9. 9
Shape describes the object in terms of a geometrical
body. Shape is also important in heat and mass
transfer calculations, screening solids to separate
foreign materials, grading of fruits and vegetables,
and evaluating the quality of food materials.
Some of the shapes are:
➢Round- Pea, soyabean
➢Elliptical- Rice, Wheat
➢Oblate- Orange, Pumpkin
➢Conic- Carrot, Ladies finger, Reddish
➢Obovate- Mango, Papaya
➢Truncate- Capsicum
SHAPE

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11. Volume
Volume is defined as the amount of three-dimensional space occupied by an object,
usually expressed in units that are the cubes of linear units, such as cubic inches and cubic
centimeters, or in units of liquid measure, such as gallons and liters. In the SI system, the
unit of volume is m3.
• Apparent volume/ Bulk volume: The volume of substance includes all pores within the
material (internal pores) and also the void volume outside the boundary of individual
particles when stacked in bulk (external pores). Bulk volume can be calculated by
measuring the volume of the bulk sample by keeping the material in a container.
• Solid volume/ True volume: This volume is the actual volume of the solid granular
material, which devoid of the volume of internal pore space as well as intergranular
spaces.
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Density

13. Density
Bulk Density:
It is the density of material when stacked or packed in bulk. Bulk density of the material is
determined by dividing the material volume inclusive of voids to weight of product. There
are two kinds of voids, voids between particles and void within particles. The bulk density
is an important in packaging requirement and is often 2-20% of true density
Tapped Bulk Density:
Tap bulk density is measured for powdery samples. The volume is measured after tapping
the powdery material so that the product is adjusted to intergranular spaces, but it cannot
eliminate all the intergranular spaces.
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14. Particle density / true density:
Density of solid material constituting the true volume of the occupied by the material,
excluding any interior pores that are filled with air.
Apparent Density:
Apparent density is the density of a substance including all pores within the material
(internal pores). Apparent density of regular geometries can be determined from the
volume calculated using the characteristic dimensions and mass measured. Apparent
density of irregularly shaped samples may be determined by solid or liquid displacement
methods.
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15. Porosity
It is the measure of void space
between the materials. It is
defined on the percentage of
volume of inter grain space to the
total volume of grain bulk.
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16. Surface Area
Surface areas of cereals are
important in investigation
related to heat transfer
studies in heating and cooling
processes.
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17. 17
Thermal Properties
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18. The emissivity of the surface of a
material is its effectiveness in
emitting energy as thermal
radiation. Thermal radiation
is electromagnetic radiation that
may include both visible radiation
(light) and infrared radiation,
which is not visible to human
eyes. The thermal radiation from
very hot objects is easily visible to
the eye.
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Thermal Emissivity(E):-

19. Thermal Conductivity
Thermal conductivity is
defined as the amount of heat
flows through unit thickness of
material over an unit area per
unit time for temperature
difference.
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20. Specific heat
Heat required to raise the
temperature by 1°C for unit mass of
the body.
Thermal diffusivity
It is rate at which heat is diffused out
of the materials. It is the ratio
between thermal conductivity to
volumetric heat capacity.
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21. Aerodynamic
Properties
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22. Aerodynamic properties
Aero and/or hydrodynamic properties are very important
characters in hydraulic transport and handling as well as
hydraulic sorting of agricultural products.
The two important aerodynamic characteristics of a body
are
1. Terminal velocity
2. Aerodynamic drag.
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23. Drag Coefficient
• It is used to quantify drag
or resistance of an object is
a fluid environment such as
air or water.
• It is a dimensionless
quantity.
• Drag coefficient is always
associated with surface
area.
• A lower drag coefficient
indicates the object will
have less aerodynamic.
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24. Terminal velocity is the maximum
velocity attainable by an object as
it falls through a fluid (air is the
most common example). It occurs
when the sum of the drag force
and the buoyancy is equal to the
downward force of gravity acting
on the object. Since the net
force on the object is zero, the
object has zero acceleration.
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Terminal Velocity

25. Relation Between
Terminal Velocity
&
Drag Coefficient
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26. Frictional Properties
Angle of repose
Coefficient of friction
Rolling resistance
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27. Angle of Repose
• The angle of repose, or critical angle of repose of a granular
material is the steepest angle of descent or dip relative to the
horizontal plane to which a material can be piled without slumping.
• The angle of repose can range from 0° to 90°.
• The morphology of the material affects the angle of repose; smooth,
rounded sand grains cannot be piled as steeply as can rough,
interlocking sands.
• The angle of repose can also be affected by additions of solvents. If a
small amount of water is able to bridge the gaps between particles,
electrostatic attraction of the water to mineral surfaces will increase
the angle of repose, and related quantities such as the soil strength.
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28. Coefficient of friction:
• Coefficient of friction is important in designing storage bins, hoppers, chutes, screw
conveyors, forage harvesters, and threshers.
• The material generally moves or slides in direct contact with trough, casing, and other
components of the machine.
• The various parameters affect the power requirement to drive the machine. The frictional
losses are one of the factors, which must be overcome by providing additional power to
the machine.
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29. Rolling resistance
• Rolling resistance, sometimes called rolling
friction or rolling drag, is the force resisting
the motion when a body rolls on a surface.
• In some material handling application, rolling resistance
or maximum angle of stability in rolling agricultural
material with rounded shape is considered. When a ball
or a cylinder rolls over a horizontal surface with a force of
the surface deforms, there will be a resultant force.
• Rolling resistance is directly proportional to the weight of
the rolling object, indirectly proportional to the effective
radius of the rolling object and directly proportional to
coefficient of rolling resistance which depends on the
rigidity of the supporting surface. 29

30. MECHANICAL PROPERTIES
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31. Mechanical Properties
• Mechanical Properties are defined as those having to do
with the behavior of the material under applied forces.
• Following this broad definition, such properties as stress
strain behavior of a material under static and dynamic
loading as well as flow characteristics of the material in air or
in water, can be classified as mechanical properties
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32. 32
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Strain: The unit change , due to force, in the size or shape of a body referred to its original
size or shape. Strain is non-dimensional quantity, but it is frequently expressed centimeter
per centimeter, m/m, mm/mm etc.
Stress: The intensity of a point in a body of the internal forces or components of force that
act on a given plane through the point. Stress is expressed in force per unit area (kg-force/
mm2)
Strength: The resistance to applied force (kg/cm)
Ultimate strength: The stress corresponding to the rupture point (kg/cm2)
Pressure: A measure of the mean normal stress on a point of body (kg/cm2)

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