| Summary: | Life is not easy for the low-income rural population of Southern Africa. This includes
those living in the informal settlements around cities. It is in part due to shortcomings
in basic services such as water, sanitation and electricity.
More than half of the households are without running water. One of the day-to-day
problems is gathering and carting sufficient water for domestic use from communal
water sources. The water is often of dubious quality, and waterborne pathogens
cause a range of bacterial, viral and parasitic diseases. Children and people with
compromised immunities are especially at risk.
Traditional energy sources for heating this domestic water, such as firewood and
charcoal, are also scarce and expensive. This, inevitably, leads to a compromise in
hygienic practices, and have a negative outcome on the health of the people.
A device is thus envisaged that can assist the people in transporting, disinfecting and
heating their water. The use of solar energy for heating the water will reduce the
dependency on traditional and conventional energy sources. Southern Africa is
blessed with abundant solar insolation. As a result, solar water heating was selected
to be used for this device, but it must then have the ability to store the hot water until
at least in the evening.
The technology and regulatory background of solar water heating were studied. An
ICS type solar water heater, with insulation and glazing, was selected for implementation.
The mobility of the device was modelled on the familiar wheelbarrow;
therefore the device was christened as the Solar Heat Barrow, or SHB. The physical
and performance requirements of the SHB were determined and specified.
A study of the history and practice of water disinfection led to the realisation that
solar pasteurisation, though possible in the SHB, will not reliably meet the day-to-day
requirements. An additional requirement for chemical disinfection was formulated. A
concept was generated for a disinfectant dispenser that could be added to the SHB
where necessary. This device was named the Dispenser. It could, however, not use
chlorine as disinfectant due to the chemical's sensitivity to heat degradation. A South
African produced disinfectant, Steripure, was then selected for this purpose.
Prototype Solar Heat Barrows, in two batches of ten and fifteen, were manufactured
using representative processes. The first batch was tested for performance and
conformance to requirements. It showed that the goals set were mostly fulfilled. In
mid-winter, water could be heated to an average of 60°C by mid-afternoon. Water at
40°C was still available at 20:00, and this performance could easily be improved with
simple human intervention. Some problems were experienced in both manufacturing
and testing. It can, however, be solved with relatively straightforward development of
the device.
A single prototype of the Dispenser was also manufactured. It served the purpose of
proving the functional principles, and a large scale manufacturing approach would be
needed for further development. The manufacturing process thereof especially has to
be addressed. The use of Steripure in the Dispenser, from the perspectives of both
disinfection and longevity at temperature, will also have to be proven.
The commercial viability and user acceptance of the Solar Heat Barrow were
evaluated. A costing exercise showed that the direct production cost of units would
come to approximately R 380. With the additional costs of operations, distribution
and marketing, the units would have to sell for at least R 600 to be commercially
viable. This would depend on a market for 60 000 units over a five year period, which
was shown to be realistic. Assuming the same market, the Dispenser will have to be
sold for at least R 100 to be commercially viable.
Users in the rural community of Mabedlane, KwaZulu Natal, evaluated the second
batch of fifteen SHB units over a two-month period. Although they were more than
satisfied with the performance of the SHB, none could afford to pay more than R 100
for the product. Other surveys in the informal settlements around Pretoria indicated
that a selling price of R 300 could still attract reasonable sales. It was, however,
shown that a policy environment does exist, in South Africa in particular, to count on
institutional support for some of the shortfall in affordability. === Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2004.
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