Desalination : discharging brine into coastal waters

• Main Author: Cher, Leo Wei Kwang.
• Other Authors: Law Wing-Keung, Adrian
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Civil engineering::Water resources
• Online Access: http://hdl.handle.net/10356/15862
• Institution: Nanyang Technological University

The increase demand of fresh water due to the shortage of water has amplified the development of desalination technologies. This also brings problems such as discharging of concentrated brine into coastal waters that may give rise to potential and permanent damage to the marine ecosystem. Concentrated brine is a solution that has a higher density than seawater, thus causing them to be negatively buoyant. The brine tends to sink and spread along the seabed. Therefore, it is vital to find the techniques to enhance mixing of brine in the “allocated impact zone” thus preventing the spread of high salinity out of this region. In this study, investigations and experiments were done to examine the mixing characteristics of the discharge by changing the geometrical shape of the nozzle from a round (circle) to a square and their results were compared. From the analysis of experimental results, the centerline trajectory of the square jet has a larger curvature than the round jet but there are no significant changes in both the location of the maximum height and impact point. It was also observed that there was no significant increase in dilution at both the centerline peak and impact point when evaluating both the square and round jets at their corresponding density. Both concentration and velocity profiles exhibit the Gaussian-like distribution at the upper layer but due to the buoyancy-induced instabilities, the lower layer tends to deviate away from the centerline trajectory. Lastly, the concentration and axial velocity of the square jet remained constant near the nozzle exit up to 3D.