Elenco Solar Energy - Manual (Page 6)

5
Experiment no. 6 The solar heater
Take your heat absorber bag and fill it with cold water. You may find
this difficult as there is very little room between the transparent cover
and the black backing. It is necessary to prepare the heat absorber
bag so that you can use it.
To do this, ask an adult to heat some water until it is hot, but not
boiling. Hold the bag at A and B and dip it into the water for about
half a minute, be careful the water will be hot. Remove it and blow
into A as if it was a balloon which you want to inflate. Hold B with
your finger to prevent the air from escaping and keep it like that for
about a minute. The bag cools and stays inflated, ready for use.
Take your heat absorber bag and fill it with cold water, then lean it against the box lid
or the polystyrene tray, in such a manner that the transparent side of the bag is facing
the sun. As the sun heats the water in the bag, the warmer water becomes lighter and
rises to the top of the absorber bag. The cold water will drop down. You may able to feel a
temperature difference by touching the bag at top and bottom.
A commercial hot water tank is very similar to our bag. A water tank is placed above
the heater and a pipe from the bottom of the tank is connected to inlet A and another
from the top of the tank to outlet B. As the water is heated, it rises and goes to the top
of the tank. As water rises in the tank, it pulls in colder water from the bottom
of the tank to be heated.
A B