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1.0 INTRODUCTION

1.1 GENERAL INTRODUCTION

Solar dryer can be defined as a special structure that

enhances the drying power of the sun and protect the

agricultural produce or food from dust, rain, birds, insects and

domestic animals while drying.

Drying is an excellent way to preserve food and solar fooddryers are appropriate food preservation technology for

sustainable development. Drying was probably the first ever

food preserving method used by man, even before cooking. It

involves the removal of moisture from Agricultural produce so

as to provide a product that can be safely stored for longer

period of time without getting spoiled.

Sun drying is the earliest method of drying farm produce

ever known to man and it involves simply laying the

agricultural products in the sun on mats, roofs or drying floors.

This has several disadvantages since the farm produce are laid

in the open sky and there is great risk of spoilage due to

adverse climatic conditions like rain, wind, moist and dust, loss

of produce to birds insects and rodents. It is totally dependent

on good weather and very slow drying rate with danger of

mould growth, thereby causing deterioration and

decomposition of produce. The process also requires large area

of land, takes time and is labour intensive.

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With cultural and industrial development, artificial mechanical

drying came into practice but this process is highly energy

intensive and expensive which ultimately increase product cost.

Recently, efforts to improve "sun drying" have led to solar

drying.

In solar drying, specialized devices that control the drying

process and protect agricultural produce from damage by

insect pests, dust and rain are used. In comparison to natural

"Sun 'drying", solar dryer generates higher temperatures, lowerrelative humidity, lower product moisture content and reduced

spoilage during the drying process. In addition, it takes up less

space, takes less time and relatively inexpensive compared to

artificial mechanical drying method. Thus, solar drying is a

better alternative solution to all the drawbacks of natural drying

and artificial mechanical drying.

The solar dryer can be seen as one of the solution to the

world's food and energy crises. With drying, most agricultural

produce can be preserved and this can be achieved more

efficiently through the use of solar dryers.

1.2 USEFULNESS OF SOLAR DRYER

The solar dryer system is used as replacement to the

traditional sun-drying methods. It is mainly used for drying of

agricultural produce. It has an improved feature that eliminates

the shortcomings inherent in the traditional sun- drying

method. Produced or food being dried in this device is therefore2


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protected against: rain, dust, birds domestic animals etc. The

usefulnes~ of the drying can be outline as follows:

1. The solar dryer, dries faster in the sense that, inside thedryer, it is warmer than outside.

2. The solar dryer system offer less risk of spoilage because

of the speed of drying (if the drying process is slow the

fruit start to ferment and the product is spoilt)

3. The solar dryer system is labour saving.

4. The quality of food or products dried using this device is

better in terms of nutrients, hygiene, texture and colour.

1.3 AIMS AND OBJECTIVES

The primary aim of this project is to design system that

provides move improved features that overcomes and replace

the traditional sun-drying method and its limitations, which

includes protection against flies, protection against rain,

protection against dust, protection against domestic animals

etc. The summary of the objective can be stated as followings.

1. To design a solar dryer that extends shelf life of farm

produce.

2. Guarantees foods security through out the year.

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3. To ensure that the food or products is protected against

rain, dust birds, insects, domestic animals etc.

4. To know the principles behind the basic construction andoperation of a solar drying equipment.

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However reports abound in literature on the 18th century

works of Archimedes on concentrating the Sun's rays with flatMirrors, Antoine Lavoisier on solar furnace, Joseph priestly on

concentrating rays using lens. In the 19th century,

development of solar distillation unit covering 4750 sq meters

of land, operated for 40 years and producing 6,000 gallons of

water from salt water per day was reported and noted

alongside with John Ericson's work on conversion of solarenergy into mechanical energy through a device which

produced the (146W) for each 9.3m2 of collection surface.

Modern research on the use of solar energy started during

the 20th century. Development includes the invention of a solar

boiler, small powered steam engine and solar battery, but it

was difficult to market them in competition with engine running

on inexpensive gasoline. During the mid 1970's shortages of oil

and natural gas, increase in cost of fuels and the depletion of

other resources stimulated efforts in the United States to

develop solar energy into a practical power source. Thus,

interest was rekindled in the harnessing of solar energy for

heating.

As a result of this, in the 1970s, Kelin, Beckmann and Duffle

(1975, 1976) developed the F-chart methodology based on

TRNSYS software simulations. They established correlations

between dimensionless design parameters and solar fraction

(ratio of the energy supplied by the solar system to the energy6


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demand of: the process). This methodology was developed for

water and air heating system. However, the focus was not on

the drying of agricultural products. The main characteristic of

the F- Chart is its simple operation and accessibility to people

not skilled in solar energy engineering.

At the end of the 1970s and beginning of the 1980s, the first

Brazilian studies on application of solar energy in drying

processes were done" at UNICAMP by a drying research During

this period Santos (1980) studied the use of collectors withbeds made of pebbles in in-bin Soy drying. The advantages of

this over flat collectors were the lower cost per unit of area, the

smaller collector area and the capacity to store energy and to

avoid temperature peaks.

Modern variations in solar dryer are to build special

enclosed drying rack or cabinet to expose the food to a flow, of

dry air heated by electricity, propane or solar radiation. In

recent time, the design of solar dryer had improved to building

of special structure that enhance the drying power of the sun

radiation in drying of produce and as well protect the produce

from external influences.

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CHAPTER THREE

3.0 METHODOLOGY

This chapter is focused on the methods employed in the

construction of the solar dryer. It reviews the design

consideration, description of main components and design

analysis. It also discusses the factors guiding material used for

the construction, fabrication techniques and engineering

analysis and its evaluation as well.

3.1 DESIGN

(a) Design Consideration:

(i) Temperature: The minimum temperature for drying food

is 30c and the maximum is 60c. Therefore, the range of

temperature for effective function of the device is 30c-

60c and any temperature above is 60c, the produce get

burnt.

(ii) Reliable: Solar dryer is more reliable than any other '

dryers because it dries produce without change in the

texture and the nutritional value.

(iii) Availability of the materials: Mild steel metal and

reflective glasses are cheaply and readily found.

Therefore, the choice of using them for the project

becomes necessary.

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(iv) Flexibility: The parabolic reflector is made flexible to

face the rays for radiation of the sun at any given angle

and direction with the aid of an adjustable screw rig and

fixture.

(v) Portability: The movement of the object from one place

to another is possible with the aid of fitted rollers. The

rollers not only assist to enhance the portability of the

object but also contribute greatly to the setting of the

parabolic reflector at the needed direction for effectivefunctioning.

(vi) Air gap: It is suggested that for hot climate passive solar

dryer, gap or holes of 4mm diameter inlet and air passage

and also reduction of exceeds heating of the produce. This

enhances the prevention of the produce from being burnt.

(vii) Drying items: The device to be designed should be

capable to dry vegetables, fruits, roots, tuber crops or

chips crop seed and some other.

(viii) Availability of power source: Sun being a natural

renewable source of energy, not only using for heatingpurpose can also be applied for drying sake without

noticing the rate of consumption.

(ix) Choice of reflector: The utilization of aluminum plate as

a reflector which enhances the effective reflection of the

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radiation to the focal point for proper drying efficiency is

considered.

(b) Description of the main components

(i) Glass Box: As the name implies, this box is constructed

using glass with reflecting surface. It houses the food

produce to be loaded in the box for drying. The reflective

surface of the glass enables the box to retain the heat

needed for drying. I t is also provided with air vent at both

sides to allow air passage out of the cabinet, thereby

releasing the moisture from the produce to aid drying.

(See diagram of the box.)

(ii) Parabolic Reflector or Concentrator: This is

constructed to have a parabolic shape made possible by

assembling sectors (segments) of equal sizes to form a

circle. It is incorporated with reflectors made of aluminum

sheet that enhance the drying power of the sun by

concentrating the heat to a focal point. (See assembling

diagram for dimensions).

(iii) Box Stand or Hanger:The box stand is constructed witha mild steel pipe. It serves as the seating for the drying

box. It has an, adjustment to suit the focal point of the

concentrator.

(iv) Main Stand: This is the main stand of the device. It is

constructed to hold the parabolic reflector in position. It is

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constructed using two circular galvanized steel rod, held in

position by mounting rods and crossed side tense rods. It

has an elevation pole for adjusting reflector seating to be

tilted at the proper angle. The base of the stand is

incorporated with three rollers to allow the reflector to be

following the direction of the sun. (see assemblies

diagrams for more details and dimensions).

(c) Design Analysis

Calculation for the focal point of the parabolic reflector 296mm

Employed the formula

F = D2

16d

Where F =focal point of the parabolic reflector.

D = Diameter of the parabolic reflector

d = depth of the parabolic reflector

F = =

F = 684mm11

d = 296mm

D = 18000mm

(180002) 3240000

296 x 16 4,736


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Calculation for the stand of the reflector

For the angle

U sing Pythagoras theorem

[AB]2 + [BC] = [AC]2 =

8202 = [AB2

] + 6502

[AB]2 = 8202 - 6502

= 672400 - 422500

= 249900.

12

820mm 650mm

C

499.9mm

B

A


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AB = 249900 = 499.9mm

Cos A = 8202+ 6202 - 499.92 x 820 x 650

672400 + 455500 - 249900.01 = 0.7931066000

Cos A = 844999.99 = 0.7931066000

A = Cos-1 = 370,3"

Area of the Triangle

Cos A = 844999.991066000

Area = 2 x X L x b

= L x b = 650 x 499.9

= 324.94mm2

Area of the top circle i.e. reflector rim.

A= r2 = or

= = 212399.2mm2

13

C

A B499.9mm

650mm

820mm

d2

4d2

4

D


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Area of mounting bottom rim

= = 3.14(610)2

= 292284.55mm2

Area of the parabolic reflector

= = 2545020mm2

Total area of the whole body

AT = 324.94+212399.2+292284.55+2545020

= 3050028.69mm2

Weight of the device i.e. the parabolic reflector and its sta is =

35kg (i.e. the weight weighed by using electronic weighingmachine).

Thus, 35 x 9.81 = 343.35N.

Therefore stress, = = 1.96 x 10-4N/mm2

Now, taking 3 as the factor safety.

Recall that;

Factor of safety =

Ultimate Stress = Factor of Safety x Working Stress

14

d2

44

d24

3.14 x 18002

343.25

1745008.69

Ultimatestress

Workin stress


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Ultimate Stress = 3 x 1.96 x 10-4

= 7.9 X 10-4 N/mm2

Calculation for the dryer box

Area of fig. A = L x b = 302 x 100 = 30,200mm2

Area of fig. B = Lx b = 210 x 100 = 2100mm2

Area of fig. C = b x h = X 210 x 202 = 21,210mm2

:.'The area of the dryer box = 30,200 + 21,000 + 21,210

= 73, 250mm2

Mass of the box = 3kg

Weight of the box 3 x 9.81 = 29.43N

Mass of a piece of a meat = 0. 12kg

15

283mm

100mm

210

310mm

B

A C

302

100mm


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Mass of 20 piece of meat = 0.12 x 20 = 2kg .I

Weight of a piece of meat = 0.12 x 9.81 = 1.18N

Weight of 20 pieces of meat = 1.18 x 20 = 23.6N

Total weight =.weight of the box + weight of 20 pieces meat

= 29.43 + 23.544 = 52.974N

Area of the dryer stand = Area of the box seat + Area of pipe A+ pipe B.

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BOX SEAT

Area of box seat = L x B

= 320 x 320 = 102 400mm2

Curve surface area of pipe A= base circumference x height

Curve surface area A = 2r x h

= dh = 3.142 x 25 x 910

= 71480.5mm2

17

320mm

320mm

Pipe A

25mm

910mm


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Note: r = d2

Curve surface area of pipe B = 2rh = dh

= 3.142 x 30 x 700 = 65982mm2

Area of the dryer stand = 102400 + 71480.5 + 65982

= 239862.5mm2

Total area = Area of dryer box "+ area of the dryer stand =

66575 + 239862.5 = 306437.5mm2

Mass of the dryer stand = 7kg

Weight of the dryer stand = 7 x 9.81= 68.67N

Stress = Weight/ Area

Stress weight on the stand =

Total weight = weight of box and 20pieces of meat + weight of

stand

18

Pipe B

700mm

30mm

Total weight on the stand

Total area


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Weight of box and 20 pieces of meat = 52.974N Weight of the

stand = 68.67N

Total weight on the dryer stand = 52.974N + 68.67N =121.644N

Recalling that total area = 306437.5mm2

:. The stress = 121.644 = 3. 969 x 10 -4 N/mm2

306437.5

Due to variation in the load i.e, items to be dried, let factor of

safety be 1.5.

Ultimate stress = allowable working stress x Factor of safety

Allowable working stress = 3.969x 10-4 N/mm2

Factor of safety = 1. 5

:. Ultimate (M) = 3.969 X 10-4 x 1.5

= 5.9535 X 10-4 N/mm2

Note: 3.969 x 10-4 N/mm2 = Allowable working stress.

3.2 Material Selection

For the construction of this device, the selection of

materials used was based on its availability and cost.

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As a result of this, two main materials were considered and

used for the construction of the device.

(a) Carbon steel: This is also called plain carbon steel. Itis a steel where the main interstitial alloying

constituents is carbon. According to American iron and

steel Institute (AISI) defines carbon steel as a steel in

which no minimum content is specified or required for

chromium, cobalt molybdenum etc. In the construction,

carbon steel was the stand of the box and the parabolicreflector, then carbon mild steel was used for the

construction of the sectors or segment that form the

parabolic reflector. Apart from the availability and

affordability of this carbon steel, it is a good choice for

construction because of its availability and hardness

though it has some disadvantages such as poorresistance to corrosion and less brittle.

Aluminium: It was used as a reflector because of its

shinning nature.

(b) Glass: This was used for the construction of the box. It

was considered because of its transparent nature and to allow

easy penetration of solar energy (heart from sun). It is

constructed with its reflective surface inside the box to allow

reflection of heat in the box thereby retaining the heat needed

for drying.

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3.3 THEORETICAL BACKGROUND OF THE STUDY

The movement of the sun's ray follows the laws of refraction.

This is illustrated as follows:

Movement of sun-rays

LAWS OF REFRACTION

The laws of refraction state as follows

21

Incident rays

Glass (medium of ray

Refracted rays in the solar

i i

^ ^


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(i) The incident and refracted rays are on opposite sides of

the normal at the point of incidence and all three are in

the same plane.

(ii) Also know as snell's law. The ratio of the sine of the angle

of incidence to the angle of the angle of; refraction is a

constant for a given pair of media.

22

N

Oi

r

Air

Glass

AO = incident rayOB = Refracted rayNNI = NormalI = Angel of incidentr =Angel of refraction

Refraction of Light (Sun)

N

S 1

TE 1

E 2

S

T

Refracted rays through the glassblock


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Straight line SS is representing the surface separation between

air and glass ,is drawn in a sheet of drawing paper on a

drawing-board together with a normal on and several lines at

various .angles to on to represent incident rays from the sun

(solar) generation power sources.

A line TT' to represent the lower edge of the glass block is now

drawn. Without moving the ruler, the block is now placed

carefully in contact with the ruler. The two lines SS' and If'

should now coincide exactly with the upper and lower verticalface of the block.

REFRACTIVE INDEX

The value of the constant sin i for a ray passing from one

medium to sin r another is called the refractive index of the

second medium with respect to the first, and is denoted by the

symbol n.

23

Sun (lightIncident rays

Refracted rays in thesolar box

Glassmedium

S1

SNELLS LAW OF REFRACTION

T1


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For simplicity, only one pair of rays has been shown, we see

that:

Sin i = AB and sin r = CDAO CO

Therefore sin i AB x COSin r AO CD

AO = CO (radii of circle)

Therefore sin i = ABSin r CD

For each pair of. rays, AB and CD are measured and recorded in

a table. The AB/CD Should be found constant, thus verifying

snell's law. Thus, if any ray passes from air into glass, the

refractive index of water = n = Sin i/Sin r.24

AB

S

P1

P

2

O S1

CE1T T1

=

E2D


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3.4 FABRICATION TECHNIQUES

Fabrication is simply the process of constructing a

mechanical structure or device by bringing together the various

components or parts using any of the method of joining. This

includes welding, bracing, soldering, bonding, riveting and

bolting.

(a) Joining Method: For the purpose of this design, the

joining methods of this device are:

(i) Welding

(ii) Bolt and nuts

(iii) Adhesive bonding

Welding process was applied for the; construction of the stands

using a welding machine and electrodes. However, the major

coupling and assembling was done with bolts and nuts cap

screws, and machine screw. They were used to fasten and hold

together the sectors (segments) that form the parabolic shape

reflector. The joining of the glass box was mainly done by

adhesive materials e.g. glue.

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(b) Machining Process: Greater part of this project was

achieved by machining. The machining process undertakenduring the construction of this device involves the cutting and

machining of the plain mild steel plate to form a parabolic

shaped sectors (segments) used for the reflector. Other

operation carried out is the cutting of the glass using diamond

cutter. During the machining processes, the materials (i.e. plain

glass and carbon mild steel plate) were measured, marked andcut to require sizes and shapes as presented in the working

diagrams. (see assembling diagram).

(c) Surface finishing: This refers to the general broad range

of industrial process that alters the surface of the manufactured

item to achieve a certain property. The finishing processes

'employed in this work are: sand papering, filing, internal and.:,

external cleaning and painting of the device (solar dryer). This

process was employed to improve the appearance and

smoothness of the manufactured solar drying device, as well as

to control the surface friction.

3.5 ENGINEERING ANALYSIS AND EVALUATION

(a) Cost analysis and Evaluation: the following cost

and Evaluations were made on the construction of

this solar dryer

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27

S/N QTY Description of material

Length &Thickness

Rate Cost

1. 1 Sheet of plain glass 1500mm x700mm 7,800 7,8002. 3 Sheet of mild

carbon steel platefull length

1800mm x900mm

4,730 14,190

3. 2 Galvanize pipe 200mm long 3,300 6,6004. 1 Pack of electrode 1,800 1,8004 Roll of sand paper 350 3505. Pack of bolt and

nuts

1,600 1,600

6. 4 Rubber roller stand 450 1,8007. 4 Tins of oil paint 375 1,5008. 2 Brush 300 3009. 1 Merge wire 900 90010. 2 Hinges 220 55011. 3 Aluminum

cardboard sheet1800mm x900mm

3,000 9,000

12. Machining shop 8,000 8,00013. Miscellaneous 4,000 4,000

Total N 58,390


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(b) Tools used

1. Hammer

2. Chisel

3. Drilling Machine

4. Drilling Bit

5. Diamond cutter

6. T-Square

7. Plier

8. Tape

9. Centre Punch

10. Riveting machine

11. Wood Bench

12. Screw driver

13. Hand file.

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FUNCTION OF THE TOOLS USED

29

TOOLS FUNCTIONHammer Used for striking the head of the chisels and

center punch

Center punch For creating dots on the work-piece to enabledrill bit centre itself for operation

Tape Used for the measurement of the variouscomponent

Diamond glass It is used for the cutting of the plane glass intotheir cutter required pattern.

Drilling machinedrilling bits

Generation of holes on the work-piece fixed inthe drilling chuck to generate the required holes

Hack saw for cutting and sawing aluminum framesVice Hold work-piece in position

Drawing set, Teesquare anddrawing board

Used for the preparation of working diagrams

Hand file Removal of small particles of metal from thework-piece

Riveting machine Used for the riveting of rivet screws

Sand paper For the smoothing of the ply-wood

Hand brush Used for the painting of the ply wood

Cutting machine Cuts the aluminum frames Into different

dimensioned partsComputer It is used for the Auto-card

System (laptop) Design of the drawing in the system


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CHAPTER FOUR

4.0 EXPERIMENTATION/TESTING AND DISCUSSION

OF RESULT

4.1 EXPERIMENTATION AND TESTING

The testing of the solar dryer was done in the month of

December for 3days. The solar dryer was placed outside with

the concentrator or reflector facing the direction of the sun. Theparabolic concentrator has been rigidly fixed to its stand at an

angle approximately 45c to the horizontal to obtain

approximately perpendicular beam of sun rays. A fresh fish

weighing 1.5 kg was cut into 3 pieces and arranged on the

drying bed in single layer. The dryer chamber door was closed

and placed in position. The result obtained for hourly reading of6 hours everyday is tabulated in the table 1-3.

4.2 RESULT

Result on 17th December, 2012

Table 1: Variation of temperature with time on the first

day.

DayTime 10am 11am 12pm 1pm 2pm 3pm 4pm

Ts (C0) 28 30 33 35 35 32 40Tp (C0) 40 48 51 55 58 54 56

MA 1.5 1.28

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(kg)

Ts (CO) = Temperature of the sun.

Tp (CO) = Temperature of the drying chamber.

M 1 = Mass of fish at 10am

M2 = Mass of fish at 4pm

Moisture removed = Ml- M2 = 1.5- 1.28 = 0.22kg.

Result on 18th December, 2012.

Table 2: Variation of temperature with time on the second Day.

Day 2Time 10am 11am 12pm 1pm 2pm 3pm 4pm

Ts (C0

) 25 27 30 32 32 31 30Tp (C0) 38 42 50 55 58 55 52MA(kg)

1.28 1.13

Ml = 1.28, M21.13

Moisture removed = 1.28 - 1.13 = 0.15kg

Result on 19th December, 2012.

Table 3: Variation of Temperature with time on the third Day.

DayTime 10am 11am 12pm 1pm 2pm 3pm 4pm

Ts (C0) 29 33 35 33 31 30 27Tp (C0) 40 42 47 48 55 49 50MA(kg)

1.13 1.03

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M1 = 1.13, M2 1.03

1.13 -1.03=0.10kg

4.3 DISCUSSION OF RESULTS

Based on the results obtained during the test of the solar

dryer, temperature a9ove 45c was recorded against ambient

temperature in the drying chamber, large quantity of moisture

O.22kg was removed on the first day because the fish was

fresh and full of moisture and it was easy for evaporation to

take place. As the fish dried, the skin becomes harden and rate

of evaporation reduced, so quantity of moisture removed on

the third day reduced to 0.10kg. Table 1 to 3 shows the

variations of inside temperature of the drying chamber with

respect to time.

4.4 MAINTENANCE AND SAFETY

The solar dryer should not be mishandled, over loaded and

never left out in the rain. The only maintenance it should need

is cleaning of the reflector surface. Since the aluminized

cardboard sheet used on the surface of reflector attracts dust,

it should be lightly wiped periodically with a soft, dry cloth. The

dryer's box should be cleaned always after use. It should also

be lightly wiped allover with a wet cloth.

The dryer's box should be handled with great care since it is

constructed with glass which makes it more fragile than any

other component of the device. When not in use, the solar32


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dryer should be stored out of the sun or covered with a

waterproof cover.

Other components such as the box stand and reflector standshould be inspected and painted from time to time to avoid

rust.

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CHAPTER FIVE

5.0 CONCLUSION AND RECOMMENDATION

5.1 CONCLUSION

In conclusion, the need for the construction of a solar

dryer arose as an alternative to ordinary sun-drying technique.

Base on the results obtained during test, temperatureabove 45c was recorded. This high temperature in the drying

chamber cause 0.22 kg" of moisture will be removed on the

first day, 0.15kg on the second day and 0.10kg on the third

day. At the end of the, third day, the mass of 1.5 kg of fresh

fish was reduced to 1.03kg. Total amount of moisture removed

was 0.47kg which is the required amount for safe storage of

fish.

5.2 RECOMMENDATION

To use the solar dryer, simply place the solar box on it's

stand facing the parabolic reflector and adjusts the tilted angle

of the parabolic reflector through the elevation pole until the

box shadow falls in the centre of the parabolic reflector for the

best focus to be obtained. This is about 684mm from the depth

of the reflector.

The parabolic reflector stand holds the reflector and allows it to

be rotated to follow the sun as it moves across the sky.

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The device should be use in area, where sunshine is plentiful.

The performance of the solar dryer can still be improved upon

especially in the aspect of reducing the drying time and

probably storage of heat within the system.

Also, meteorological data should be readily available to

designer, and users of solar products. Proper account of heat

loss, reflective power of the reflector and focal point of the

systems should be considered to ensure maximum efficiency

and effectiveness of the system on further design. Furtherrecommendation on usage is considered as follows:

1. Pre-treatment of the food such as blanching (boiling/

steaming) before drying is advisable.

2. Effective drying is accomplished with a combination of

heat and air movement.

3. Typical drying time ranges from 1 to 3 days depending on

sun, air movement humidity, quantity and type of food.

4. Food to be loaded in the box should be cut into thin slice

and spread out to allow free air movement.

5. Allow food to cool completely before storing.

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REFERENCES

Beckman W. A. Klein S. A. and Duffie J. A. (1977), Solar heating

Design Published by John Wiley 1st

edition, New York.

Barbara K. (1999). The design of solar dryer and cooker,

published by stainable living center, Arizona, U.S.A.

Duffie J. A. and Beckman W. A. (1991), Solar Engineering of

thermal process, 2nd edition. Published by John Wiley,

New York.

George M. Kaplan (1985). Understanding Solar Concentrators,

Published by VITA, USA.

Harringshaw, D. (1997). All about food drying.

Published Ohio State, University.

Olaleye D. O. (2008), the design and construction of Solar

Incubator. Project Report submitted to Department of

Mechanical Engineering University of Agricultural

Abeokuta.

Sukhatme S. p. (1996), solar energy. Principles of thermal

collection and storage, McGraw Hill Publishing Company.

Whitefield D. E. (2000) solar dryer system and the internet.

Important resources to improve food preparation,

proceedings of international conference on solar cooking.

Kimberly South Africa.

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