Effect of intermittent operation on the productivity of a single basin single slope passive solar still containing nanofluids

الملخص EN

This study assess the effect of using two nanofluids; composed of Ferric Oxide (Fe2O3) which is a metalic oxide and Red Clay Brick Waste (RCBW) containing over 60% SiO2 a nonmetalic oxide nanoparticles in ordinary water upon the performance of a basin solar still.

An increase in the still productivity was observed for both the tested nanomaterials while the gain achieved with Fe2O3 exceeded that for RCBW at all the concentrations used.

For both materials, the rise in concentration adds to the still yield which reached its maximum values; 11% and 9.5% for Fe2O3 and RCBW respectively at 0.01 vol % then a depltion in the still yield was recorded with additional increase in concentration.

The operation of the tested solar still is intermittent as the basin fluid is kept stationary during offshine sun hours.

This leads to a continous decrease in thr still productivity over its operating period due to the loose of nanofluid stability causing aggregation, clustering and gravity aided sedimentation of the nanoparticles.

These effects negatively affect the optical and heat transfer characteristics of the nanofluid suspension which determines the rate of vaporization and condensation of water in the still.

Over 70% depltion in the still yield relative to that obtained in the first day of operation was recorded in the third day of operation for Fe2O3 nanofluids while four consecutive days of operation were needed for RCBW nanofluids to cause similar effect.