Water desalination with flat plate solar energy collector
2018 – 2019
أ.د. أشرف سعيد
Our project “Water Desalination Assisted With flat plate” shows the experimental results of a solar desalination system to produce potable water for drinking purposes from either sea or salty ground water. This system has two components: a flat plate solar collector, and a desalination tower with heat recovery mechanism. The flat plate solar collector can be used in either direct or indirect heating mode. In the first case, the water that runs through the collector absorber is the condensate produced in the desalination tower. This condensate flows down on sidewall to a clean water tank at the bottom of the tower. The hot water in the tank evaporates and condenses on the walls of the first stage, directly heating the salty water in this stage. In the indirect heating, solar radiation is absorbed in the collector and transferred to a thermal oil flux, which transport this heat to a mass of salty water in the desalination tower. The heat transfer takes place in a heat exchanger at the lowest level, or the first stage in the desalination tower .Two units were built and tested, one for each heating mode. The desalination tower has six stages and a water circulation system through the stages to avoid salt concentration. The results show the good system thermal performance, and that improvements can be made to reach even higher potable water production rates. The water (polluted sea water and salty well water) laboratory test results show that the desalination process eliminated the Coliform group bacteria, being appropriated for human use. The flat-plate solar collectors are probably the most fundamental and most studied technology for solar-powered domestic hot water systems. The overall idea behind this technology is pretty simple. The Sun heats a dark flat surface, which collect as much energy as possible, and then the energy is transferred to water, air, or other fluid for further use.
These are the main components of a typical flat-plate solar collector:
- Black surface – absorbent of the incident solar energy
- Glazing cover – a transparent layer that transmits radiation to the absorber, but prevents radiative and convective heat loss from the surface
- Tubes containing heating fluid to transfer the heat from the collector
- Support structure to protect the components and hold them in place
- Insulation covering sides and bottom of the collector o reduce heat losses.