Effect of covering by black polythene sheet and coal powder on nearby surfaces of sand bed solar still: Studying heat and mass transfer

Abstract

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.The lack of potable water poses a big problem in the world. Solar stills have long been used as an easy-to-operate and popular water production unit. In present work, the real situation near the seashores where wet sand is available in abundance with brackish water is being simulated and experiments were conducted. The experimental results are helpful for the coastal area where there is abundance of saline water but lack of potable water. The two experimental arrangements were compared for the heat and mass transfer within the single slope solar still and the yield in the month of March at Raipur (Latitude 21.16N and longitude 81.42 E) India. It has been observed that the daily distillation yield is more in second case where surrounding mass of sand has been converted as heat storage that enhances heat and mass transfer. The wet sand top surface temperature that resembles the water temperature of solar still of both arrangements increases slowly as the sun rises up and reaches to its maximum at 1:30 pm of 1st as well as 2nd day by rise of 231 % and 125% more with comparison to morning temperature respectively for solar still S-1. The same water temperature for solar still S-2 also reaches to its maximum at same time 1:30 pm of 1st as well as 2nd day by rise of 234 % and 139 % respectively. It has been observed that the second solar still S-2 remains always ahead as for as yield is concerned. Finally in two days of observation the second still gives 12.20% more yield (6.205 litres in comparison to5.530 litres) per m2 basin area in 48 hours of the basin in comparison to the first solar still S-1 under consideration. This yield can be increased significantly by increasing the area of the basin. One more interesting conclusion is the fact that in still wet sand nearly behaves as a free water surface.dc201