Design and Construction of A Solar Dryer for Mango ... - Tropentag

50 cm
Inlet vent
10 cm
Fig.2 Side view of the constructed dryer.
103 cm
6
vent
Exit
76 cm
10 cm
13 cm
A simple box frame 103cm long, 100cm wide and 76cm high at the back and 50 cm high in
front made of angle irons (2.54cm x 2.54cm) was fabricated. Sheets of mild metal sheet 0.1cm
thick were welded onto three sides and bottom of the fabricated frame.
Glass wool was used as insulator with a thickness of 5 cm and placed above the bottom mild
metal sheet. A 98cm x 99cm corrugated galvanized metal sheet was placed above the glass wool
and fitted to the bottom of the box by nails and rivets in addition to wood. The corrugated metal
sheet then painted in black as absorper plate.
Two tray holders made of angle iron (2.54cmx2.54cm) were welded in such away to hold
tray inside drying chamber. The lower holder was 15cm above the absorber plate and the upper
was 15 cm a part.
Masonite sheets of 0.3cm thick were used as insulators and fitted to the three inner sides of
the frame.
Aluminuim foil sheets were glued to masonite and used as moisture barrier; prevent moisture
from masonite and to reflect incident solar radiations to absorber from sides.
One panel of a 4-mm thick transparent glass (102.5cm x 99 cm) was glued to the top part of
the frame with silicon rubber sealant, which allow the expansion of glass at high temperature.
The glass used was low in iron content (water- white glass) because of its good transmissivity for
solar radiation. The glass was inclined at an angle of 15 due south , which is the angle of the
latitude of the experimental site.
In side the drying chamber there were two movable wire mesh trays that can be placed on
their holders. The frame of each tray was constructed from wood with dimensions of (97cm x
94cm ), while the tray had a surface area of (91cmx87.5cm ) and 7cm deep, with effective area of
91cm x 84cm. Each tray was made of wood and galvanized wire mesh.
For loading and unloading of material to be dried ,a hinged door was made for this purpose.
The hinged door was constructed from galvanized metal sheet (0.1cm thick), 3cm thick cork was
used as insulator. The door was sealed to prevent air leakage between the surroundings and the
drying chamber.