A Columnar Shear-Assisted Freeze Desalination System

Abstract

Abstract Freeze desalination is an emerging desalination technique. Previous studies showed that shear-assisted freeze desalination could achieve drinking water production through one freezing cycle. However, the productivity of this approach is relatively low and the energy consumption is relatively high. To address these drawbacks, we developed a columnar shear-assisted freeze desalination system, where seawater flows through a vertical tube with ice formed at the inner surface of the tube. At constant seawater flow rates, potable water is produced at high flow rates. Unfortunately, the drinking water productivity remains low (0.48 kg·m–2·h–1) and the energy consumption is high. By linearly lowering the seawater flow rate during freezing, the drinking water productivity reaches 2.28 kg·m–2·h–1, a 4.8-fold increase compared to the cases with constant flow rates, and the total specific energy consumption is significantly reduced from 11.64 to 1.20 kWh·kg–1. Experiments with natural seawater are also conducted. Due to the relatively low salinity of the natural seawater used (32.53 g·L–1), the productivity of drinking water and the total specific energy consumption reach 5.32 kg·m–2·h–1 and 0.83 kWh·kg–1, respectively. The results indicate that the proposed desalination system is promising for commercialization.