Paper presented at the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July, 2008.
A new energy-efficient and sustainable desalination system
has been developed in this research. This system operates under
near-vacuum conditions created by exploiting natural means of
gravity and barometric pressure head. The system can be
driven by low grade heat sources such as solar energy or waste
heat streams. Theoretical and experimental studies were
conducted to evaluate and demonstrate the feasibility of the
proposed process. Theoretical studies included thermodynamic
analysis and process modelling to evaluate the performance of
the process driven by the following alternate energy sources:
solar thermal energy, solar photovoltaic/thermal energy,
geothermal energy, and process waste heat emissions.
Experimental studies included prototype scale demonstration of
the process using direct solar and a combination of solar
photovoltaic/thermal sources. In the tests using direct solar
energy, freshwater production of 5 L/d was achieved using
direct solar energy alone, at efficiencies ranging from 65 to
75%. In the tests using solar photovoltaic/thermal energy,
freshwater production of 10 L/d was achieved, at efficiencies
ranging from 65 to 90%. Specific energy required for this
process to produce 1 kg of freshwater was 2926 kJ, all of which
was derived from solar energy.
