Multi-finned falling film desalination system with separated heat and mass transfer processes

Most conventional thermal desalination systems use horizontal or vertical tube arrays or parallel-plate structures in the evaporation and condensation units. Desalination is usually carried out in coupled heat and mass transfer processes which easily lead to scaling on the heat transfer structures which limits the desalination performance. This paper presents an innovative desalination system that performs falling film evaporation with separated heat and mass transfer processes using highly compact multi-finned structures. The system was developed and tested to study both the transient and steady state performance and the influence of the operating temperature and feed seawater flow rate on the fresh water yield. The results show noticeable improvement in the fresh water yield per unit heat exchanger volume and demonstrate the capability of the system to produce fresh water at operating temperatures as low as 36 °C. The separation of the heat exchange and the evaporation enables further enhancement of both processes, which cannot be easily achieved in conventional designs with coupled heat and mass transfer processes.