Freezing desalination: Heat and mass validated modeling and experimental parametric analyses

Abstract Freezing desalination (FD) is an attractive water treatment process with relatively low energy consumption and simple maintenance. In this work, indirect brine crystallization experiments are conducted to investigate the salinity gradient in the formed ice by freezing brine under different conditions and evaluate the effects of these conditions on freezing time and heat transfer. These experiments demonstrate salinity gradient reaching 60% reduction in axisymmetric tray of 20 cm diameter in the first 5% formed ice. The 1st principle heat balance model is developed to predict the freezing time and heat transfer. It was validated experimentally and the discrepancies are less than 5%. Sensitivity analysis based on the develop model were conducted to assess system parameters including the brine initial temperatures, freezing source temperatures and subcooling temperatures. Results reveal that the freezing time increases linearly with initial fluid and subcooling temperatures, but decreases exponentially with cooling source temperature. Freezing source temperature plays a significant role on the freezing time. Additionally, multistage-freezing desalination procedures show that potable water can be obtained from 35 g/L solution brine after four successive freezing steps at 5% ice yield in each freezing.