空调蒸发器铜管翅片间隙腐蚀研究

Study on Fin Crevice Corrosion Mechanism of Copper Tube in Air-conditioning Evaporator

针对售后空调蒸发器铜管翅片间隙腐蚀泄漏问题,结合空调实际生产情况及售后样件,从翅片间隙产生原因、间隙腐蚀机理、腐蚀介质来源及间隙腐蚀预防措施等方面进行分析。研究发现,蒸发器翅片间隙产生原因为翅片成型异常、胀管收缩、翅片少片等;空气中SO2、Cl2、H2S、NH3等通过翅片间隙溶于间隙冷凝水中形成腐蚀性离子,以及铜管表面残留有机溶剂和挥发油等水解产生的羧酸,使铜管表面形成自腐蚀微电池,造成腐蚀破坏。此外,蒸发器翅片间隙结构又形成间隙内与间隙口处铜管表面的氧浓差电池,使腐蚀以自催化形式进行,进一步加快腐蚀速率。对此提出控制翅片间隙、控制铜管表面腐蚀介质残留、提高铜管耐蚀性等预防措施。

Leakage caused by fin crevice corrosion of copper tube in after-sale air-conditioning evaporators is studied in the aspects of the cause of the crevice,the mechanism of the crevice corrosion,the source of the corrosive medium and the preventive measures for crevice corrosion,combined with the actual production of air conditioner and after-sale samples.It is found that the reasons for the fin crevice of the evaporator are abnormal fin formation,expanding shrinkage,and less fins,etc.SO2,Cl2,H2S,and NH3,etc,in the air dissolve in the condensate water through the fin crevice to form corrosive ions.The corrosive ions and the carboxylic acid produced by hydrolysis of organic solvents and volatile oil remained on the surface of the copper tube,cause the formation of a self-corrosive microbattery on the surface of the copper tube,eventually leading to the copper tube corrosion damage.In addition,the structure within the crevice forms the oxygen concentration difference battery between entrance and inside of the crevice,which makes the corrosion proceed in a self-catalytic manner,further accelerating the corrosion rate.In view of this,preventive measures such as controlling the fin crevice,controlling the corrosion medium remained on the surface of the copper tube,and improving the corrosion resistance of the copper tube are proposed.