An experimental investigation of the solar still system

Abstract

Using solar energy to evaporate the brackish water and the resulting steam is condensed and collected as final potable water is called solar desalination. It operates on the same principle as rainwater which can be achieved by the solar still. It was realized that solar desalination for producing potable water can compete economically with other coveting methods.

This project aims to carry out a research on the solar still system and to design and fabricate a solar still prototype which can use the vacuum for increase the productivities. In the design, the solar still prototype consist of a basin (500mm long, 300mm wide and 180mm high) with a glass cover (487mm long and 295mm wide) sitting on it and properly sealed by silicone sealant. The glass cover angled 15 º respects to the horizontal. The distilled water is collected in a plastic tray which attached to the lower end of the glass cover. The distilled water is drained out by a water tube and measured directly by a collection vessel. A vacuum port locates at the back side of the still is used for vacuumize the still by a vacuum pump. A vapor trap is attached on it to prevent vapor escapes during vacuuming.

The experiments are carried out in Singapore and two different conditions were used: the solar still prototype was operating under sunlight with and without the vacuum condition. The duration time was 9½ hours for each condition from morning 8.30 o’clock to 18 o’clock. The temperature, humidity and distilled water volume were recorded at a regular time interval during the experiments. The productivity was then calculated and compared respectively.