New trends in physics teaching, v.4; The ... - unesdoc - Unesco

A solar cooker
PREPARATION AND SUBSTITUTES FOR MATERIALS
1.
2.
3.
4.
5.
6.
7.
8.
If there are no big boxes available,
(a) use old newspapers to make papier mache and form a box from them.
(b) dismantle small boxes and paste or sew the pieces together to form a bigger one.
(c) form any low conductivity material into a box.
If black paint is available, it can be a substitute for the carbon paper.
For a more durable cooker, aluminium sheet can be used in place of aluminium foil, provided
the bottom part is painted black.
Mirror can be used instead of aluminium foil as reflector.
Gauge 10 transparent plastic sheet can be used if gauge 12 is not available.
The big carton should be at least 6 cm longer and wider than the small box for better insulation.
The greater the absorption area of the box, the more energy wil be collected. A 0.6 m2 area
or bigger gives a better efficiency. Generally, the lower the height of the cooking area, the
higher the temperature that wil be attained.
The plastic sheet should be stretched to avoid convection.
PROCEDURE AND QUESTIONS
A. To make the outer box, A
a. Cut and construct the outer box A from a large carton according to the dimensions
given in figure 1.
The final box has an open top and a 30 cm square hole cut in the taller end.
Note that the angle shown on the figure is equal to the approximate latitude of the
Philippines. If constructing the cooker elsewhere, the design must be modified so that this
angle is equal to the local latitude.
Figure 1.
3 03