Solar Dryer Made with Locally Available Indigenous Materials

Dr. Sreekanta SheelEmail: drsheel63@gmail.com

Mobile: +8801714083764

Solar Drying System Made with Indigenous Materials

Drying is an important method of food preservation through which, fruits and vegetables may be preserved year round. Solar drying is a low cost drying technique in which, the commodities may be dried in a hygienic way using natural energy. The present activity aims to introduce fabrication techniques of solar dryer to be used for drying cabbage, cauliflower, jute leaf etc. Also the drying operation for banana and potato chips will be performed using the solar dryer. The activity will be performed under an small scale agro-processing industry to be conducted by the heterogeneous group of 15 members comprising mainly poor women. Through implementation of the activities at commercial level, income generation for the group is expected and thus, the group will find out a way for attaining food security as well as through processing of the agricultural crops, the post-harvest loss of them will be reduced to a great extent.

Fabrication of Solar Dryer

For fabrication of solar dryer, five partitions are made with thin sleepers of bamboo according to Fig. 2. Measurements are shown in the figure. If the partitions are placed vertically, it will be shaped into a box as Fig. 4. The steps of fabrication of dryer are given bellow serially:

1. Sleepers are made from tall and straight bamboos and cut into desirable sizes (Fig. 2 and Table 1).

2. Thin sleepers are made from bamboo and 10 mats (Chatai) are prepared for 5 partitions as Fig. 3.

3. Some paddy straws are collected.

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Fig. 1. Box type direct solar dryer

Fig. 2 Lay-out of the sleepers of bamboo

4. For making partitions, at first, one set bamboo sleeper is placed in plain ground according to Fig. 2, and then a bamboo mat is placed above it. Paddy straw is spread on it with a thickness of 2.5-5 cm. Then again one set of sleeper is placed on it.

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Fig. 3 . Five partitions of the solar dryer

5. One extra sleeper is placed at each of four sides. Then lower and upper sleeper is affixed together with rope or wire. Thus 5 partitions are made.

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2 2 2 3 o o o o o o o o

3 2 2 2 2 2 2 2 3

3 2 2 3 3 2 2 2 2 2 2 2 3 3 2 2 3

o o o o o o o o3 2 2 2 2 2 2 2 322

2 2 2 3

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Front Partition

Backside Partition240 cmX 80 cm

O O O O O O O O

Base Partition240 cm X 120 cm

O O O O O O O O

Side Partition

6. Eight round holes of 5-8 cm diameter are prepared maintaining equal distances at each of the partitions to be placed in front and back positions.

7. The side partitions are placed vertically surrounding the lower partition and joined together with rope or wire according to Fig. 4.

8. Four bamboo pillars are prepared and placed one pillar at each of four corners, so that the whole dryer can be placed 15 cm above ground.

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Fig. 4 Sketch of the solar dryer

9. Inner sides of the partitions are coloured with black colour. For preparation of black colouring material, some charcoals are powdered, flour is mixed with water and heated to make it adhesive and the coal powder is mixed with it uniformly. The adhesive material is then spread at the inner sides of the partitions with the help of a brush made with jute fibre. The coloured sides are then dried in the sun properly.

10. A polythene or polypropylene sheet is purchased from market according to the measurement given in Table 1.

11. The dryer box is covered with the polythene/polypropylene sheet. Four bamboo sleepers are affixed with the end sides of the polythene/polypropylene sheet so that, the sheet does not move or hang due to wind. It should be noticed that, the polythene/ polypropylene sheet will be placed in such a manner that, the holes of the partitions will not be covered.

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80 cm

30 cm

80

120 cm

240 cm

O O O O O O O O

O O O O O O O O

12. For preparation of trays, 4 rectangular wooden frames (like chowki without top) are made with wooden bars according to the measurements shown in Table 1. The top of the trays are covered with plastic net.

The required materials for fabrication of solar dryer are shown in Table 1. with quantity/no. and measurement in detailed.

Table 1. Calculation of building materials for a solar dryer

Sl. No.

Building Material Measurement(cm)

Quantity/No.

1 Bamboo sleeper 240 28 No.120 32 No.137 6 No.

80 20 No.30 20 No.

2 Bamboo mat (Chatai) 240 × 120 2 No.240 × 80 2 No.240 × 30 2 No.

120 × 120 1 No.3 Polythene/ polypropylene sheet 270 × 170 1 No.4 Bamboo pillar 95 3 No.

45 3 No.5 Paddy Straw - 10 Kg6 Wheat flour - 2 Kg7 Charcoal powder - 2 Kg8 Tray 107 × 48 4 No.9 Wooden bar for trays 5×4×153 8 No.

5×4×46 4 No.4×2.5×153 8 No.

4×2.5×46 4 No.5×4×10 16 No.

10 Plastic net for trays 107×48 4 No.

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