International Journal of Engineering and Technology Volume 6 No.8, August, 2016

ISSN: 2049-3444 © 2016 – IJET Publications UK. All rights reserved. 260

Development of Software for Design and Construction of Rotary Dryer for

Drying Ground Cassava

Ademiluyi F. T Department of Chemical/Petrochemical Engineering. Faculty of Engineering,

Rivers State University of Science and Technology,

Nkpolu, Port Harcourt, Nigeria

ABSTRACT

A software was developed in this study using Microsoft Visual Basic.Net for the design of rotary dryer for drying ground cassava.

Basics equations which are needed for the design of part of the dryer is also presented. A graphical user friendly interface and 2D/3D

graphics for determination of Heat load required for drying, Diameter of dryer, Length of dryer, Number of flights, Radial height of

flight, the thickness of rotary shell, the thickness of insulation, Air blower power, the power of motor for feed drive, the power of

motor to drive drum of dryer and the total heat resistance through the dryer were developed. The data generated from the software

developed "Rotcassavsim" v1.0 was also used to construct a bench scale rotary dryer. This software developed is a useful tool for

engineers, operators, and designers of rotary dryer for drying ground cassava.

Keywords: Rotary Dryer, Drying, Software, Design, Ground Cassava, Rotcassavsim, Construction

1. INTRODUCTION

The rotary dryer is one of the most popular types of

convective dryers used in the chemical industry for large-

scale production. Apart from being commonly operated in the

agricultural, chemical and pharmaceutical industry; rotary

dryers have become increasingly important in other sectors

because they cover a wide range of material, sizes and shapes.

This type of dryer permits easy scale up of pilot dryer to

industrial.[1] Drying is the best method of preservation of

fermented and unfermented ground cassava, and the rotary

dryer was proposed to be the best dryer for drying ground

cassava [2,3] The rotary dryer is good for continuous

operation, and can dry large quantity of ground cassava , it's

easy to operate, with low maintenance cost.

According to the Food and Agriculture Organization of the

United Nations [4], more than 228 million tons of cassava

were produced worldwide in 2007, of which Africa accounted

for 52%. In 2007, Nigeria produced 46 million tons making it

the world's largest producer of cassava. Unfermented ground

cassava can be processed into Unmodified starch, modified

starch and glucose which are used for many purposes: directly

as cooked starch food, custard and other forms; thickener

using the paste properties of starch in the manufacture of

baby foods. They are also use as filler contributing to the

solid content of pills and tablets and other pharmaceutical

products etc.; binder, to consolidate the mass and prevent it

from drying out during cooking (sausages and processed

meats); and stabilizer, owing to the high water-holding

capacity of starch. Starch makes a good natural adhesive.

There are two types of adhesives made of starches, modified

starches and dextrins: roll-dried adhesives and liquid

adhesives. Cassava dextrin is preferred in remoistening gums

for stamps, envelope flaps and so on, because of its adhesive

properties and its agreeable taste and odour. Unfermented

cassava with high starch content, which are not good for

human consumption was also recommended for production of

ethanol in the work of Ademiluyi et al., [5]. Local polymer

(cassava starches) can also be used as a substitute for

imported sample in viscosity and fluid loss control of water

based drilling mud [6] .

Dry fermented ground cassava is a favourite food in Nigeria

and is produced mainly by female small-scale gari processors.

More than 90% of the gari produced from cassava is toasted

in open steel-pans while the rest is toasted in open clay-pots

[7]. Despite the various applications of cassava products,

preservation of cassava after harvest before processing into

cassava starch is still a problem in Africa. The Cost of rotary

dryer is not affordable to farmers in Nigeria and Africa hence

the need to make available design equations that can be used

to fabricate major parts of the rotary dryer for medium scale

and large scale drying. and also provide solution to the

storage problem of cassava after harvest.

Some of the equations available for designing of rotary dryers

are scattered in Engineering books and few in journals. Most

authors only look into the modeling and kinetic aspect of the

drying using rotary dryer [8,9,10]. Other only give equations

for determination of diameter of dryer, design of Flights,

residence time and length of dryer [11,12] but most past

works did not provide enough information on how to

determine the thickness of plate used in the fabrication of

Rotary Drum of the dryer, determine the thickness of

insulation for the rotary dryer, sizing the power of air blower,

sizing the motor to drive the feed, and sizing the motor to

drive drum of dryer etc. Drying softwares [13-17] available

International Journal of Engineering and Technology (IJET) – Volume 6 No. 8, August, 2016

ISSN: 2049-3444 © 2016 – IJET Publications UK. All rights reserved. 261

are not suitable for design of component part of rotary dryer

for drying fermented ground cassava.

Hence the objectives of this work are to provide an insight

into design equations for designing a rotary dryer and

development a user friendly software which can be easy used

by fabricators of Rotary dryers for drying ground cassava.

2. MATERIALS AND METHODS

2.1. Parameters required for Rotary Dryer design

A.Required Input Parameters

Dryer inlet Air Velocity

Product Inlet Mass Flow Rate

Mass of cassava to be dried

Density of cassava to be dried.

Air Inlet Temperature.

Rotational speed of feed drive

Torque to drive feed

Material for construction of dryer

Material for insulation of rotary drum

B. Required Output Parameters for Rotary Dryer

Heat load required for drying Q

Diameter of dryer, D

Length of dryer. L

Design of Flight

o Number of flights.

o Radial height of flight

the thickness of Dryer

the thickness of insulation.

Material of insulation: Rock wool or glass wool

Material of construction of dryer: stainless steel

Air blower power

the power of motor for feed drive

the power of motor to drive drum of dryer

The total resistance RT

Resistance of hot air

Resistance of stainless steel dryer

Resistance of insulation (rock wool)

Resistance of stainless steel cylinder covering

insulator

Resistance of air at surrounding of dryer

2.2. Design equations and models for Drying ground

cassava in a rotary dryer.

2.2.1. Determination of Heater load Required for Drying

The heat transfer within a control volume has been considered

in terms of an overall or volumetric heat transfer coefficient

defined by the equation

lmv TaVUQ (1)

where Tlm is the logarithmic mean of the temperature

differences of the air and the product at the inlet and outlet of

each dryer element. The coefficient Uva consists of the

product of a heat transfer coefficient, Uv, based on the

effective area of contact between the gas and the solids, and

the ratio a of this area to the dryer element volume. The use

of this coefficient eliminates the need to specify the area over

which heat transfer occurs.

where Uva will be calculated using the Myklestad equation

[18]

8.0

52.0

A

GaU a

v (2)

The Heater load will be used to size the heater for drying the

material:

For fermented ground cassava Ademiluyi et al., [19]

determined the Specific heat load empirically as a function of

the inlet air temperature, the inlet air velocity and mass flow

rate of feed (fermented ground cassava) as presented in

equation 3.

Q = Heat load of rotary dryer =

)889.291172.30358.0541.0( faiai MT kJ /kg

hr (3)

where

Tai = inlet air temperature in oC

Vai = velocity m/s,

Mf = mass flow rate of feed kg/hr

2.2. Diameter of dryer

The diameter of dryer is obtained from the mass flow

rate of air and the mass flow velocity of air

Area of dryer

=

s) m(kg/ air of velocity Mass

(kg/s)air of rate flow Mass2

m2

(4)

Diameter of dryer =

21

aM

4

aGx

m (5)

Input parameters for calculation of Diameter of dryer:

Ga = Mass velocity of air kg/m2 sec

Ga = ( - 0.0028 (Tai +273) + 1.9967* Va ) kg/m2 sec

(6)

Ma = Mass flow rate of air kg/s [20] =

)()1( aoaipaa TTCY

Q (7)

where for fermented ground cassava

Ya = absolute humidity of air (kg water/ kg dry air)

Tai = inlet air temperature of dryer (oC)

Va = is the specific volume of air m/s

Tao = outlet air temperature (oC)

Cpa = Specific heat capacity of air = 1.026 kJ/kg oC

International Journal of Engineering and Technology (IJET) – Volume 6 No. 8, August, 2016

ISSN: 2049-3444 © 2016 – IJET Publications UK. All rights reserved. 262

Mf = mass flow rate of feed kg/hr

2.2.3. Length of dryer

The length of dryer is obtained from equation 8 [20] once the

diameter and heat load Q has been calculated from equations

1 and 5.

L =

lma TDG

Q

67.0

25.59

1000*

(8)

Where

Q = Heat load = (Q' x Mc) /3600) kJ/s

Mc = Mass of cassava to be dried kg

D= diameter of dryer m

Ga= Mass velocity of air = Ga = ( -0.0028 (Tai +273) +

1.9967* Va ) kg/m2 sec

Where the log mean temperature difference in

equation 8 is

.)/()(In

)()(

vaovai

vaovaiLM

TTTT

TTTTT

(9)

Tai = inlet air temperature oC

Tao= outlet air temperature oC

Tv =(Vaporization temperature) was obtained from Nt

Nt

.)(

)(

vao

vai

TT

TTIn

so that )1(

)(

Nt

aiao

Nt

v

TTT

(10) for an air–water system, where Nt is the number of transfer

units that lies within the range 1.5–2.5 for an economic

design of a rotary dryer, Tai is the inlet air temperature, and

Tao is the outlet air temperature. The L2/D ratio for a dryer

should be between 3 – 10.

Total length of dryer L 2 = L + 2L1

Fig 1 Schematic diagram of dryer and insulator

2.2.4. Design of Flights

Number of flights = (πD/off Distance between flight)

(11)

Assume Distance between flight to be 10%

Lip angle of flights = 360/( number of flights)

(12)

Radial height of flight hrf (Radial flight height: D/12 to

D/8)

hrf = (Diameter of drum)/12 (13)

2. 2.5.Calculation of the thickness of stainless rotary

Dryer [21]

) 2(

)1000* (t d

i

i

Pfjxx

DxP

.+ corrosion allowance (mm )

(14)

Where: td is the minimum thickness of dryer m, Pi = Design

pressure N/mm2, (take as 10-15 per cent above operating

pressure), , D= Diameter of Dryer m, f = Design stress based

on material of fabrication N/mm2 =100 and Maximum design

dryer temperature take j=1 (assume full radiograph)

Therefore the outer Diameter of rotary drum

Do = D + 2 x td (15)

2.2.6.Calculation of the thickness of insulator cover shell

[21]

) 2(

1000) (

i

Si

scPjxfx

xDxPt

.mm + corrosion

allowance (16)

Where: tsc is the minimum thickness of insulator shell m, Pi =

internal pressure N/m2, DS = Diameter of insulator shell m, f

= Design stress of insulator shell based on material of

fabrication N/m2

2.2.7. Determination of the thickness of insulation of

rotary dryer. tisl

The thickness of insulation is important in the design of

rotary dryer. A good insulation will reduce heat lost and

reduced drying time. Fermented cassava need to gelatinize

properly in the rotary dryer before drying and good insulation

will make this possible. Rock or glass wool can be used as

insulator. In order to determine the insulator to be used in the

design, we will consider the heat resistance through the dryer

wall, insulator , insulator cover and the surrounding air. Fig 2

and 3, shows a cross section of the dryer and the heat

resistances

Fig 2 Cross section of Rotary Dryer

L

L2

L1 L1

Insulator cover

D/2 + td + tisl + tsc

Dryer

Insulator

International Journal of Engineering and Technology (IJET) – Volume 6 No. 8, August, 2016

ISSN: 2049-3444 © 2016 – IJET Publications UK. All rights reserved. 263

Fig 3 Rotary Dryer and insulator and resistances.

Heat lost by dryer to surrounding is

Q = (Tai – Tatm)/RT (17)

The total resistance RT = Resistance of hot air + Resistance of

stainless steel dryer + Resistance of insulation (glass wool) +

Resistance of stainless steel cylinder covering insulator +

Resistance of air at surrounding of dryer as shown in Figure

2 above.

RT = R1+R2+R3+R4+R5 (K/W) (18)

Calculate Resistance of hot air R1 using equation 19 [22]

R1 =LDhva *)2/(**2*(

1

(K/W) (19)

Where heat transfer coefficient for hot air in dryer hva

))(4/(

)(

2

atmai

atmai

va

TTD

Q

TTA

Qh

(W/m2K

R2 = Resistance of stainless steel dryer = )***2(

)/( 12

sdkL

rrIn

(21)

Ksd conductivity of stainless steel dryer = 17 W/m K , td =

thickness of rotary dryer drum

R3 = Resistance of insulation (glass wool) =

)***2(

)/( 23

inskL

rrIn

(22)

Kins conductivity of insulation (rock wool) = 0.04 W/m K , tisl

= thickness of insulation round dryer

Resistance of stainless steel cylinder covering insulator

R4=)***2(

)/( 34

sckL

rrIn

(23) Ksc

conductivity of stainless steel dryer insulator cover = 17

W/m K and tsc = thickness of stainless steel cylindrical

insulator cover

Resistance of air at surrounding of dryer

R5 = 1/((hout*2*π*(tisl + D/2 + td + tsc )*L)) (24)

Where hout is heat transfer coefficient for air outside dryer

W/m2 K =15W/m2K

Tai = inlet air temperature of dryer

Tatm = atmospheric temperature

Tos= temperature of the outside surface and π =3.142

Hence summing equation 19 -24 gives equation 25

RT =

LDhva *)2/(*142.3*2*(

1+

)**142.3*2(

)/( 12

sdkL

rrIn+

)***142.3*2(

)/( 23

inskL

rrIn+

)**142.3*2(

)/( 34

sckL

rrIn+

Lhout *) t+ t+ D/2 + t(*142.3*2*(

1

scdisl

(25)

Rate of heat loss per m length of dryer = rate of heat lost

from the atmosphere.

T

amai

R

TTQ

=

5R

TTQ amos (26)

hence

atmos

amaiT

TT

TTRR

5 (27)

where RT = total heat resistance through the rotary dryer

Equating equation ( 25 ) and ( 27 ) we have equation (28)

LDhva *)2/(*142.3*2*(

1+

)**142.3*2(

)/( 12

sdkL

rrIn+

)***142.3*2(

)/( 23

inskL

rrIn+

)**142.3*2(

)/( 34

sckL

rrIn+

Lhout *) t+ t+ D/2 + t(*142.3*2*(

1

scdisl

=

Lhout *) t+ t+ D/2 + t(*142.3*2*(

1

scdisl atmos

amai

TT

TT

(28)

Replacing the Radius with Diameter of drum we have

equation (28)

R1

R2

R3

R4

R5

Hot

Dryer Air

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ISSN: 2049-3444 © 2016 – IJET Publications UK. All rights reserved. 264

LDhva *)2/(*142.3*2*(

1+

)**142.3*2(

)2//)2/(

sd

d

kL

DtDIn +

)**142.3*2(

)2//(tD/2t disl

ins

d

kL

tDIn +

)**142.3*2(

)2//(tD/2t disl

sc

dislsc

kL

tDttIn +

Lhout *) t+ t+ D/2 + t(*142.3*2*(

1

scdisl

=

Lhout *) t+ t+ D/2 + t(*142.3*2*(

1

scdisl atmos

amai

TT

TT

(29)

Choose tisl (thickness of insulation) beginning from (0.03-

0.3m) till left and right hand equation of equation 29 are

equal.

2.2.8. Determination of Diameter of insulator cover

plate (DSD)

Let DS = Diameter of insulator shell, from geometry

Ds = D + 2 td +2tisl (30)

so that the diameter of insulator cover plate

DSD = Ds +2ts (31)

Where D = Diameter of drum dryer. td= the thickness of drum

dryer shell and tisl= thickness of insulator. ts is thickness of

insulator cover shell

The insulator cover plate for the two ends of the insulator

shell are two in number.

Fig 4 Diameter of insulator shell and cover plate

2.2.9. Calculation of the Speed of rotation of the dryer

Revolutions per minute N = Peripheral Speed/Circumference

of Dryer

Assume the peripheral speed of rotation to be 1.5m/s =90

m/min.

Circumference of Dryer drum = πDs

2.2.10. Determination of the power required to drive

the rotary dryer drum

)000,100(

)73.0390.130.34( WWDDwNBHP SD

(32)

Where:

BHP: Break horse power required to drive drum [23]

N : No of revolution per minute

D in m = diameter of drum dryer m

DSD in m = Shell diameter .(rotary drum +insulator shell)

w = Load of material to be dried (kg) = volume of the shell x

density of ground cassava

Assume 10% hold up (H) then

w = 4

1LDH m (33)

W = weight of rotary drum of dryer + weight of material

+weight of insulation + weight of stainless steel cylinder

covering dryer insulator + weight of stainless plate to cover

insulating cylinder of dryer.

W=

4

)( 2

1

2

2 LDDsd +

4

1LDH m+

4

)( 2

2

2

3 LDDsli

+

4

))( 2

3

2

3 LDtD scsc +

4

))(2

2

1

2

3 LDtDx

scsp ( 34)

ρsd= Density of stainless drum

ρm = Density of material to be dried

ρisl= Density of insulator

ρsc= Density of insulator cover

ρsp= Density of stainless plate used to cover ends of rotary

dryer

D1 = diameter of rotary dryer drum.

D2 = Di+2td = diameter of rotary dryer drum + 2*Thickness

of rotary drum of dryer (td)

D3= D2 + 2tisl ( where tisl= thickness of insulator)

2.2.11. Determination of Air Blower Power for Dryer

The power of air blower is a function of volume of air

entering the blower and the air inlet temperature. The blower

power is expressed as: [22]

Power of blower = 2.72 x 10-5 Q * P (34)

Ds

DSD

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But Q = ( Mamx* Tai * 22.4)/(29 *Tst) so that

Power of blower (Pb) =2.72 x 10-5 *(( Mamx* Tai *

22.4)/(29 *Tst) ) * P ( 35)

Q - volume of air m3/hr

Tai -Temperature of inlet air

P – blower operating pressure, cm water column= 100 cm

water column

Mamx = Maximum Mass flow of air required for drying kg/hr

(Similar to Ma in equation 4)

Temperature of inlet air = Tatm

2.2.12. Determine the power required to drive the feed

The power required to drive the feed is expressed as:

to drive the feed

where HP =

5252

(torque) T x N (36)

HP = horse power

n = rotational speed of feed motor rpm,

T = Torque, lbf- ft

The power to drive the feed and the power required to drive

the rotary dryer drum were calculated in horsepower because

most motors are normally rated in horsepower.

2.2.13. Material of insulation of rotary dryer drum:

Rock wool or glass wool

2.2.14. Material of construction of rotary drum: Stainless

steel is recommended as material of construction for drying

ground cassava because of the high moisture content of

cassava and end use of the dried products are used for food

and drug related products.

2.2.15. Experimental Work

In order to generate input data and test the validity of the

software developed using equations above and obtain input

data such as Dryer inlet Air Velocity, Product Inlet Mass

Flow Rate, Mass of cassava to be dried, Density of cassava to

be dried, Air Inlet Temperature and optimum rotational

speed of feed drive motor. A known cassava cultivar was use

in this study - TMS 30572. The choice of this cassava cultivar

TMS 30572 was based on its preference by farmers, because

of its high yield and suitability for gari processing [24]. The

cassava was peeled, washed, grated and packed in sack for

pressing. The dewatered mash was allowed to ferment

naturally for 72hrs; sieved with a mesh of 3.5mm and then

dried in a bench rotary dryer. Changes of the air conditions,

including air temperature and moisture loss along the dryer

length was measured as drying progresses. The Data obtained

from previous works on Modeling drying kinetics of

fermented ground cassava in a rotary dryer and Effects of

Drying Parameters on Heat Transfer during Drying of

Fermented Ground Cassava in a Rotary dryer carried out by

Ademiluyi et al., [3] and Ademiluyi et al., [19] was also used

in the design.

2.2.16. Algorithmic Formulations For Software

Development

A Programs was written using all the design equation with

Microsoft Visual basic .NET (2013) to create a user friendly

package for determination of output parameters for designing

a rotary dryer for drying fermented ground cassava. The

algorithm used is shown in Fig 5.

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Fig. 5 Flow Chart for Software Development

3. RESULTS AND DISCUSSION

3.1. Description of Software package

The software developed in this work for the determination of

parameters needed for the design of rotary dryer for drying

ground cassava is referred to as "Rotcassavsim" v1.0. Fig. 6

shows the main window of the software which contains the

main menu. This software featured a user–friendly graphic

interface. A click on the menu bar and then the rotary dryer

input window will popup. Fig 7 shows input window, on this

window all the input data needed for the calculation of major

part of the rotary dryer will be entered. The first input data

"Drying air velocity/flow rate" involves the velocity of inlet

air from the air blower which, from the work of Ademiluyi

(2009) is within the range of 1 - 1.55m/s for proper

gelatinization of ground cassava during drying.

The second input data is "Product inlet mass flow rate"

(kg/hr). This is the mass flow rate of the ground cassava to be

dried within a specified time. The change in this value will

affect the heat load, length, Diameter of the rotary dryer. The

"air-inlet temperature" is also an important input data which

for fermented ground cassava should be between 140 - 190oC

for proper gelatinization and unfermented ground cassava

(dried starch) should between 70oC - 100oC. A thermocouple

and temperature controller should be installed to keep the

temperature constant in the design.

Figure 6. Main window of software

The fourth data on the input window is the rotational speed

of the drum, and for fermented ground cassava the speed of

the drum should be slow enough to allow proper

gelatinization of the product (i.e 6 - 12rpm Ademiluyi et al.,

[19] while for unfermented cassava a faster rotational speed is

needed since the product is not expected to gel. The torque to

drive the feed is also necessary. The torque needed to drive

the feed should be specified in a way that the ground cassava

will not clog the hopper chamber due to high moisture

content. Ground cassava's moisture content is expected not to

Compute R3, R4, R5, RT, RT2

Declare and initialize

variable used

If Abs(RT -

RT2) <=

0.0001

Start

Compute Tv , deltaTlm, Q

Compute Ga , Ma, Dd, ,L

Compute Nf, hrf, td , Di , hva, R1, R2, R3, tsc

Let tisl = 0.03

Compute tisl = tisl+ 0.01

If Abs(RT -

RT2) <= 0.002

Print Q, Dd, L, Nf, hrf, td, Di, tisl, R1,

R2, R3, R4, R5, RT, Ds, tsc, N, w, W,

BHP, Qvol, Pb, HP

Compute Ds, N ,w , D1, D2, D3,

W BHP , Qvol, Power for blower, HP

Stop

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be greater than 50% moisture on wet basis if rotary drying is

required for the drying. A screw press should be constructed

alongside the rotary dryer during the design. The material of

insulation should be rock wool, or glass wool. Insulation of

dryer is very important to avoid excess heat losses. The

insulation material used in this software was rock wool and

all the properties of rock wool were used in the soft ware.

Other input data like "atmospheric temperature" in oC was

specified on the input data window. The material of

construction of used in this soft ware is stainless steel and the

density of material was inculcated in the software.

The percentage hold up of ground cassava inside the dryer

was also specified on the input data window. The last input

data box is the density of ground cassava (kg/m3) to be dried.

A click on the compute box lunches the data output form and

all the parameters needed for the design of the rotary dryer is

displayed as shown in Fig. 7.

Fig 7 Input data window for ground cassava rotary dryer design

software

The output data window for design of rotary dryer for drying

fermented ground cassava is shown in Fig. 8. The first output

data box is the heat load required for drying. The value

obtained will enable the designer determine the rating of

heater required for the drying. The heat load actually

determines the length of the dryer. The second and third box

on the left displays the diameter and length of dryer. The ratio

of L/D for a dryer should be between 3 - 10. The value of L/D

obtained for this design was 5.0 which falls within the

acceptable limits.

The number of flights inside the dryer and the radial height of

flight is also displayed, which doe this design is 8. Flight are

essential in design of rotary dryer for drying ground cassava

to avoid lump formation of product as drying progresses. The

thickness of shell used to construct the stainless drum of the

rotary dryer, the thickness of the material of insulation

(preferable glass or Rockwool), thickness of insulator shell

are displayed on the output data window of Fig 6. The

resistance of heat through the wall of the dryer, insulator,

insulator cover and shell are also displayed so as to motor the

heat loss through the wall of the dryer.. The value obtained

for this design in Fig 6 for the total heat resistance RT was

1.81k/W which shows that the total heat loss through the wall

from the dryer is negligible.

Fig 8 Output data window for ground cassava rotary dryer

design software

The speed of rotation of the rotary dryer drum is also

displayed on Fig 8 . In practical terms this can only be

achieved by installing a speed controller alongside the motor

for the rotary dryer. The speed controller must be installed to

step down the speed at which the feed is driven through the

feed hopper since manufacturers speed of most motors are

high than 1000rpm.The power of the motor of the air blower

and the power for the feed drive motor were also displayed in

Fig 8.

3.2. Construction of Rotary dryer

The output data from Fig 8 were used to construct a bench

rotary dryer for drying of fermented ground cassava with a

capacity of 4kg/hr to validate the software. Fig. 9a- d shows

the parts of the rotary drawn with Autodesk Inventor

professional 2016. Fig 9a is the sectional diagram of rotary

drum, Fig 9b is sectional diagram of the product receiver. the

design of the product receiver is based on the geometry of the

rotary drum, Fig. 9c is the heater housing which were also

designed based on the geometry of the rotary drum. Fig.9d is

the dryer stand. Fig 9e and f. display a pictorial diagram of

International Journal of Engineering and Technology (IJET) – Volume 6 No. 8, August, 2016

ISSN: 2049-3444 © 2016 – IJET Publications UK. All rights reserved. 268

the rotary dryer designed at different elevations while Fig. 10

is the rotary dryer constructed from the software developed.

Fig 9a Sectional diagrams of Rotary dryer drum and

insulating Shell

Fig 9a Sectional diagrams of Rotary dryer product

receiver

Fig 9c Sectional diagrams of Rotary dryer heater

housing

Figure 9d shows the hopper attached to the rotary drum, the

sizing of the hopper is based on the design of the feed drive

motor. From the result from the output data box in Fig 8, a

one Horsepower (~ 1 Hp) motor will be adequate for this

design. The diameter of the shaft of the feed motor

determines the size of the hopper orifice in Fig 9d

.

Fig 9d Sectional diagrams of Rotary dryer hopper

International Journal of Engineering and Technology (IJET) – Volume 6 No. 8, August, 2016

ISSN: 2049-3444 © 2016 – IJET Publications UK. All rights reserved. 269

Fig 9e shows the rotary dryer stand. The design of the stand is

based on geometry of rotary dryer, heater housing and product

receiver.

Fig 9f Showing pictorial diagrams of rotary dryer

constructed at different elevations from the data

generated from the software designed.

.

Fig 8 Rotary dryer Constructed

4. CONCLUSION

Development of Software for Design and Construction of

Rotary Dryer for Drying Ground Cassava was carried out in

the study. A program was written using Microsoft Visual

Basic.NET 2013 and all the basics equations which are

needed for the design of part of the dryer were inculcated in

the design. A graphic user friendly interface and 2D/3D

graphics for the determination of heat load required for

drying , diameter of dryer, length of dryer, design of number

of flights, radial height of flight, the thickness of rotary shell,

the thickness of insulation, air blower power, the power of

motor for feed drive, the power of motor to drive drum of

dryer and the total heat resistance through the dryer were

developed. The data generated from the software developed

was also used to construct a bench scale rotary dryer. This

software developed is a useful tool for engineers, operators,

and designers of rotary dryer for drying ground cassava.

ACKNOWLEDGEMENTS

Thanks to the management of the Raw Materials Research

and Development Council Nigeria (RMRDC) who sponsored

the development of this software and the management of

Tertiary Education Trust Fund, Nigeria (TETFund) who

provide funds for the construction of the Rotary dryer.

Special thanks to Professor M.F.N Abowei , Prof M. J.

Ayotamuno (River State University of Science and

Technology, Port Harcourt) and Professor B. O. Oyelami

(National Mathematics Center, Abuja) for their support.

REFERENCES

Bacelos, M. S., Jesus, C. D. F. and Freire, J. T. (2009)

Modeling and Drying of Carton Packaging Waste in a

Rotary Dryer, Drying Technology, 27, 9, 927 — 937

International Journal of Engineering and Technology (IJET) – Volume 6 No. 8, August, 2016

ISSN: 2049-3444 © 2016 – IJET Publications UK. All rights reserved. 270

Audu, T. O. K and Ikhu-Omoregbe, D. I. O. (1982). Drying

characteristic of fermented ground Cassava. Nigerian

Journal of Engineering and Technology Development, 7, 2–

20.

Audu, T. O. K., (1983) Determination of the optimum

parameter of rotary dryer for gari processing, Chemical

Engineering Journal, 26, 157-163.

Ademiluyi F.T and Puyate, Y. T. (2013) Modeling drying

kinetics of fermented ground cassava in a rotary dryer,

Transnational journal of Science and Technology UK , 3, 5,

1- 24 ISSN 1857-8047 Available:

http://tjournal.org/tjst_may_2013/01.pdf

FAO (2009) Food outlook. Food and Agriculture

Organisation Corporate Document Repository

Retrieved:http://www.fao.org/docrep/012/ak341e/ak341e06.h

tm.

Ademiluyi F.T, and Mepba H. D (2013) Yield and Properties

of Ethanol Biofuel Produced from Different Whole Cassava

Flours, ISRN Biotechnology

Ademiluyi F.T, Joel O. F. and Amuda A. Kazeem (2011)

Investigation of local polymer (cassava starches) as a

substitute for imported sample in viscosity and fluid loss

control of water based drilling mud Journal of Engineering

and Applied Science

6 (12).

Ademiluyi, F. T. (2009). Development of predictive models

for drying fermented ground cassava. Ph.D Thesis,

Department of Chemical/Petro-Chemical Engineering,

River State University of Science and Technology,

Port Harcourt, Nigeria.

Menges H.O, and Can Ertekin (2006), Mathematical

modeling of thin layer drying of Golden apples Journal of

Food Engineering 77,119–125

Iguaz .A, Esnoz. A, Martýnez G., Lopez, A., and Virseda .P

(2003) Mathematical modelling and simulation for the

drying process of vegetable wholesale by-products in a

rotary dryer. Journal of Food Engineering, 59, 151–160

Jia C.C Yang W. T.J Siebenmorgen A.G Cnossen (2002)

Development of Computer Simulation software for

single grain kernel drying , tempering, and stress analysis

Transactions of the American Society of Agricultural

Engineers 45 (5) 1485-1492.

Lisboa, M. H; Vitorino, D. S.; Delaiba, W. B.; Finzer, J. R.

D. and Barrozo, M. A. S. (2007) A study of particle

motion in rotary dryer Braz. Journal of Chemical.

Engineering. 24 (3) São Paulo July/Sept.

Jules Thibault, Pedro I. Alvarez, Roman Blasco & Rolando

Vega (2010) Modeling the Mean Residence Time in a

Rotary Dryer for Various Types of Solids, Drying

Technology: An International Journal 28, (10) 1136-1141.

Mathew G. Pelletier, Joseph W. Laird, Gary L. Barker, and

Suhas V. Patankar (2001) Analysis and Design of a Drying

Model for Use in the Design of Starch-Coated Cottonseed

Dryers The Journal of Cotton Science 5:234-242

Kemp, I.C.; Hallas, N.J.; Oakley, D.E. (2004), Developments

in Aspen Technology drying software. Proceedings of

14th Intl Drying Symposium (IDS), Sao Paulo, August

Volume B, 767-774.

Kemp, I.C. Drying software: past, present and future, Drying

Technology 2007, 25(7), 1249-1263.

Menshutina, N.V.; Kudra, T. (2001) Computer Aided Drying

Technologies. Drying Technology , 19 (8), 1825-1850.

Zhen-Xiang Gong and Arun S. Mujumdar (2016) Software

for Design and Analysis of Drying Systems

Retrieved : http://www.arunmujumdar.com/

File/Simprosys/DryingSoftwareArticle. pdf.[Accessed 23rd

June 2016]

Myklestad, O. (1963). Heat and mass transfer in rotary dryers.

Chemical Engineering Progress Symposium Series, 59

(41), 129–137.

Ademiluyi F.T., Abowei, M. F. N., Puyate, Y. T.,

Achinewhu, S. C. (2010) Effects of Drying Parameters on

Heat Transfer during Drying of Fermented Ground Cassava

in a Rotary dryer. Drying Technology. 28: 4, 550 - 561.

McCabe, W. L Smith J.C Harriott .P (2001) Unit Operations

of Chemical Engineering McGraw-Hill Book Co, 6th ed., New

York

Sinnott R.K (2005) Chemical Engineering

Design Volume 6 fourth Edition Elsevier Butterworth-

Heinemann

Eastop, T.D. & McKonkey, A. (2002). Applied

Thermodynamics for Engineering Technologists (5th ed.).

London: Pearson Publishing.

Perry, R.H.; Green, D.W. and Maloney, J.O., Perry's

Chemical Engineers Handbook, McGraw-Hill Book Co, 6th

ed., New York (1984).

Eke, J. (2006). Physico-chemical and pasting properties of

starch and tapioca from different cassava. Ph.D Thesis,

Department of Food Science and Technology, River State

University of Science and Technology, Port Harcourt, Nigeria

.