Impact of feed spacers on flow dynamics in seawater desalination: A review

Seawater desalination is a key technological approach to address the global problem of water scarcity. Spacers in water treatment membrane modules play a critical role in the water treatment process. The use of a spacer improves fluid dynamics, enhances heat and mass transfer efficiency, and effectively mitigates concentration polarization, reduces fouling risks, and increases the long-term operational stability of the system as a whole. Although numerous novel spacer designs have been proposed in recent years, their large-scale commercialization still faces significant challenges. This review summarizes the critical strategies for improving hydraulic performance, mitigating scaling issues, and enhancing heat and mass transfer performance of spacers. It focuses on structural innovations that aim to optimize spacer performance and meet the diverse demands of various desalination methods. On the basis of a comprehensive analysis of spacer performance in typical application scenarios, it summarizes the limitations of current research, identifies future research directions, and highlights the potential of novel spacer designs to improve desalination efficiency. This review enhances understanding of the role of spacers in desalination systems and offers new research directions for future developments in seawater desalination technology.