Freeze desalination: Current research development and future prospects

Abstract

Desalination is the solution for water security in regions with insufficient resources. This comes at high energy cost and hence improving desalination technologies translate into huge saving. Freeze desalination (FD) is emerging as an attractive low energy and less corrosion alternative to provide the needed fresh water. The maturity of the heat driven cooling technology and solar cooling have given freeze desalination an additional momentum. This paper summarizes the latest research progress done on FD that continues to push this technology towards deployment. It gives an overview of the FD configurations and highlighting its pros and cons, presents the recent experimental work that investigate the physics of the technology, and reviews the latest high-fidelity numerical modeling of brine freezing and salt diffusion away from crystal lattice which taps on the advanced development in computational power and multiphysics integration. This enables one to identify the challenges facing FD technology and stating the prospect and foreseeable research. The finding suggests that direct and indirect FD have been evolved well while the indirect is becoming the mainstream method for risk avoidance, while vacuum freezing and eutectic freezing are still facing large obstacles in their application. For direct FD, gas hydrate combined with liquefied natural gas (LNG) regasification has been popular topics to reduce their desalination cost. Simulation and modeling development in indirect FD continue to improve the knowledge of the mechanism of ice growth and salt entrapment which are key problems that need further experimental and numerical investigations. Nonetheless, the current successful application of LNG cold energy in freeze desalination, the hybridization of FD with conventional desalination technologies, as well as ultrasound assisted freezing are promising directions for FD commercialization.

Keywords: Crystal growth; Energy; Freeze crystallization; Freeze desalination; LNG; Solutes concentration; Ultrasound.