<p>This study explores the dynamic characteristics of plate-type raw sewage heat exchangers and their correlation with fouling thermal resistance. To better understand this process, a mathematical model specifically designed for raw sewage was developed, which derived a transfer function for internal wall temperature under varying flow conditions. Comprehensive experimental results demonstrate that flow rate variations significantly reduce the fouling deposition rate but simultaneously prolong the formation time of fouling thermal resistance. Additionally, the wall temperature exhibits a slight increase, further enhancing fouling thermal resistance and highlighting the intricate interplay between fluid dynamics and heat transfer. These findings establish a theoretical framework for optimizing the design of plate-type sewage heat exchangers and provide actionable insights for improving their operational performance.</p>