Research progress on the deposition mechanisms and mitigation of particulate and crystallization fouling in heat exchangers

Fouling deposition in heat exchangers is a critical issue that reduces heat transfer efficiency, increases energy consumption, and compromises long-term operational stability. This paper systematically reviews the research progress on the formation mechanisms and mitigation strategies of particulate fouling and crystallization fouling in heat exchangers. The deposition of particulate fouling is a multifactor coupling process primarily influenced by fluid dynamic conditions, particle characteristics, and surface properties. It involves a dynamic balance of particle transport, adhesion, and re-detachment on the heat transfer surface, with the initial sites and deposition patterns strongly regulated by flow direction. Crystallization fouling originates from the nucleation and crystal growth of inverse solubility salts in supersaturated solutions, with its formation highly dependent on local temperature fields, ion concentration distributions, and surface energy characteristics. In high-salinity or particle-laden complex systems, crystallization and particulate fouling may interact synergistically, leading to the formation of a composite fouling layer with a denser structure and greater thermal resistance. In terms of monitoring and mitigation, this paper comprehensively reviews the principles and application performance of multiple strategies, including fouling monitoring techniques (e.g., machine learning-based predictive models and infrared thermography), chemical methods (e.g., antiscalant addition and chemical cleaning), and physical methods (e.g., surface modification, online mechanical cleaning, and physical water treatment). Finally, the major challenges currently facing the field are summarized, and future research directions are outlined. The aim is to provide insights for a deeper understanding of fouling mechanisms and the development of efficient and reliable mitigation technologies, thereby enhancing the overall performance and operational reliability of heat exchangers.