Fundamental Study of Non-Contact Water Salinity Sensor by Using Electromagnetic Means for Seawater Desalination Plants

With the increase of the world's population and the improvement of living standard, the need to use fresh water will accordingly rise. As a result, we will face the problem of water shortage. To ensure the supply of water in a stable manner, seawater desalination plants are built with a view to filtering sea water into fresh water. In this paper, we propose the development of a non-contact water salinity sensor to measure the salinity in the water that has already been processed in seawater desalination plants. This non-contact water salinity sensor is configured from two parts; the exciting coil and the detection coil, which is considered the most important, with a figure-eight coil. When the exciting coil is supplied by high frequency of alternating current, the electromotive force will be induced in the figure-eight coil when changes in the salinity of the medium happen, the phase difference between the current supplying to the exciting coil and the electromotive force being induced in the figure-eight coil will accordingly change. As mentioned above, we develop a non-contact water salinity sensor to measure the salinity based on this phase difference. The sensor was able to determine the 0.05% salinity, which is the upper limit of the freshwater.