Investigation on solar still greenhouse evaporator to enhance the yield of potable water from saline water tannery

Abstract

Water is vital for the survival of biotic organisms on the earth. The rapid population growth and industrialization have led to the pollution of natural water sources like rivers and underground water, thus ending up in shortage of potable water for human beings. However, impure brackish and saline water can be purified using solar desalination technologies to produce potable water. Single basin single slope passive solar stills are commonly used to disinfect and desalinate brackish and saline water to produce drinking water. But the main bottleneck haunting the wide dissemination of this system is its poor yield per unit area. Hence, this study aims to overcome this problem through the usage of latent heat energy storage medium, dual glazing and rotating cylinders wrapped with cotton wick in solar still and to compare the distillate yield of these modified solar stills with that of the conventional solar still (Type A). All the experiments were carried out at the Institute for Energy Studies, Anna University, Chennai, India. During the experimentation with seven modified solar stills and one conventional solar still, the temperature of absorber plate, water, air, inner glass cover surface and outer glass cover surface temperature of the still and yield of the still was recorded for every 30 minutes. The first set of experiments made use of three different stills namely Type A, Type B and Type C solar still, while both Type B and Type C still were incorporated with same amount of paraffin PCM which starts to melt at 55.1°C. The PCM encapsulation container used in Type B still was plain tube whereas in Type C still concentric tube annulus was used. In Type B still, 16 numbers of tubes having an inner diameter of 25.4 mm were incorporated to the basin of the still to accommodate the paraffin PCM, whereas in Type C still, the PCM was embodied in between the annulus of the outer tube of diameter 31.75 mm and the inner tube of diameter 6.35 mm newline