In its simplest form, a SWH consists of an
absorber, a storage tank, insulation, piping and a transparent cover.
Solar energy heats the absorber surface and a heat-transfer fluid
(indirect) or water (direct) flowing through tubes attached to the
absorber. If a heat-transfer fluid is used, there is a heat exchanger
that then heats the water. The heated water is transferred to the
insulated storage tank either with a pump (active) or without a pump
through natural convection (passive). A transparent cover (glass or
plastic) is placed above the absorber to reduce heat losses due to
radiation and also on account of wind flowing over the absorber. The
bottom and sides of the absorber are covered with insulation to reduce
both types of heat losses. The absorber, cover and insulation are
placed within a plastic or metal container.
The basic design of a solar geyser is based on a collector box
assembly situated below a storage tank. Within the box is an absorber
made of black copper sheets, to the back of which are attached copper
pipelines. The absorber is covered with a transparent glass and
insulated at the back and sides to reduce heat losses. The collector
works like a miniature greenhouse trapping heat that is transferred to
the water in the pipes. Cold water flows from the bottom of the
storage tank to the collector, from which heated water rises to the
top of the storage tank. To maintain the functioning of the system, a
constant supply of cold water must be available, for which an overhead
storage tank on the roof is convenient (Figure 1,2
& 3).
The general requirements for installing a solar geyser include a
shadow-free roof or ground area with sufficient strength to carry the
collector and storage tank (3 m’ of area capable of supporting 200kg
of static load for every 100 1pd). There must be cold water
available at a minimum head of 3m. There must be provision to adjust the inclination of
the collector to receive maximum solar radiation, a drain plug to
flush the system, an air vent to release air locks, and proper
supports and piping.
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