Experimental Investigation on Finned Solar Still with Enhanced Thermal Energy Storage

In the present study, a novel solar still incorporated with fins and phase change material (PCM) based energy storage, was designed. To investigate the influence of fins and energy storage unit, four cases of stills were considered. In case I, a conventional type was considered, whereas square hollow fins were fitted over the basin liner of the still in case II. In addition to fins as in case II, case III employs energy storage unit wherein PCM was packed beneath the basin liner. Case IV was similar to case III except the extension of fins into the storage unit. The addition of fins above the base liner improved the absorber surface area and the extension of the same beneath the basin liner enhanced the storage efficiency. Experiments were carried out on all the four modules with a constant basin water depth of 2 cm. The maximum productivity of the conventional solar still was found to be 3.25 litre/m2/day. On the other hand, the results reveal improvement in productivity of 17.54%, 48.61% and 55.69% with cases II, III and IV, respectively. Although stills with energy storage unit exhibited higher exergy efficiency, the presence of fins in the PCM increases the internal irreversibilities. The cost of water yielded by modified solar still (MSS) used in case IV is proved to be less as compared to conventional solar still (CSS). Further, the payback period of MSS is found to be lesser than that of CSS.