Exergy and thermo-economic analyses of a combined solar organic cycle with multi effect distillation (MED) desalination process

Solar energy with different configurations of multi-effect distillation process is thermo-economically evaluated. In this work, two different combined solar cycles with different configurations of multi effect distillation (MED) processes are considered. In the first technique, the solar energy is directly utilized from the solar collector field via evaporator heat exchanger to the first effect of the MED process. This technique produces only potable water. In the second technique, the exhausted energy from the organic Rankine cycle (ORC) turbine is used in the first effect of the MED process. The second technique produces power electricity and desalted water. The comparison is implemented according to the operation of Parabolic Trough Collector (PTC) with toluene organic oil and water working fluids. Therminol-VP1 Heat Transfer Oil (HTO) is considered for indirect vapor generation operation across the solar field and evaporator heat exchanger. The comparisons are manipulated according to 100 m3/day of distillate product as a case study. As a result, only desalination technique is considered more attractive than desalination and power technique due to higher gain ratio and lower solar field area needed. Parallel feed configuration is dominated against the forward feed with feed heater configuration while increasing the number of effects to more than 12 effects.

Research Highlights► Different configurations of MED desalination process are compared. ► Parallel feed configuration could be dominant while increasing the number of effects. ► Combining solar organic cycle with such configuration is required. ► The combination is evaluated based on exergy and thermo-economic analyses. ► Stand alone technique harvests lower solar field area and higher gain ratio.