Solar thermal desalination system with heat recovery

This work presents the energy and mass balance equations, the numerical simulation results for the production rate, and the experimental laboratory water tests for a thermal desalination unit with a heat recovery system. The system components are a solar collector and a desalination tower, although the system can be operated with other energy sources. The desalination tower is made of six stages and a water circulation system through the stages to avoid salt concentration. The numerical results calculated using ambient data show that the production rate can reach 25 L/m2/d, which is by a factor of five times greater than the rate of a basin-type solar desalination unit. The water (polluted seawater and well water) laboratory tests results show that the desalination process eliminated the Coliform group bacteria and reduced the salt concentration to very low levels.

The solar desalination unit can reach very good thermal performance, as shown by the numerical simulation, when well built. The results show that it can reach a water production rate of 25 L/m2/d for a value of 4.8k Wh/m2/d of solar radiation. This represents a rate of 5.2 L/kWh m2 and a factor of five to six times greater than the tank-type distiller. The problem of salt concentration has been taken into consideration through the continuous water flow through the unit. The laboratory tests presented in Table 1 for very polluted seawater and for well water show Subscripts c circ e hx in k l leak o out r w — — — — — — — — — — — — Convection Circulation Evaporation Heat exchanger Inlet Conduction Loss Leakage Oil Outlet Radiation Water