Application of Exergy Analysis to Improve Performance a Weir-type Cascade Solar Still

In this paper, comparison between irreversibilities of different parts weir-type cascade solar still for a particular day has been carried out. By writing unsteady exergy balance for different parts of solar still system such as glass cover, brackish water and absorber plate, some equations are obtained for different irreversibilities of the system based on climatic and operating parameters. Simulation results show that in input mass flow rate 0.065 kg/min, the largest value of irreversibility rate belongs to absorber plate among of all of irreversibility rates of the system. Irreversibility rate of absorber plate in input mass flow rate 0.065 kg/min is 84.17% of all of system irreversibility rates. Whereas irreversibility rates in other parts of solar still can be neglected. Also study on exergy fractional shows that evaporative exergy fractional have more significant with respect to convective and radiational exergy fractional.