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Based on the previous background regarding the electrochemical protection of heat exchangers, the following are the operating conditions of heat exchangers for which anodic protection is not suitable: conditions involving non-oxidizing dilute acids/weakly corrosive media. Anodic protection relies on metals forming a stable passivation layer; in non-oxidizing media such as dilute sulfuric acid and dilute hydrochloric acid, metals are unable to form such a passivation layer, and anodic polarization actually accelerates metal dissolution and corrosion, rendering it completely ineffective as a protective mechanism. In environments with high levels of chloride ions, such as seawater or highly chlorinated circulating water, these ions can destroy the passivation layer and cause pitting. Conventional metals like steel are unable to form a stable passivation layer, resulting in the complete failure of anodic protection; in such situations, cathodic protection is a more suitable solution. In operating conditions with large fluctuations in medium composition, anodic protection requires extremely high precision in potential control. If the concentration of the medium, its oxidizing capacity, and temperature fluctuate significantly and frequently, the range of the passivation zone becomes unstable, which can easily lead to passivation corrosion or activation corrosion, making system maintenance very difficult. Heat exchangers made of unactivated-passivated metal materials: Anodic protection is only applicable to activated-passivated metals such as carbon steel, stainless steel, and titanium, which can form a passive layer; metals like copper and aluminum, which are unable to form a stable passive layer, cannot be protected against corrosion through anodic protection at all. In heat exchangers with complex structures deep within the tubes, the protective effect of anodic protection is limited to a short length at the tube inlet; it is difficult to establish a uniform passivation potential deep inside the tubes, making it impossible to provide effective protection for the entire device. Such structural configurations are not suitable for this purpose.