溴化锂中央空调换热管泄漏原因分析

ANALYSIS FOR LEAKAGE OF HEAT EXCHANGERS USING IN CENTRAL AIR-CONDITIONING UNITS WITH LITHIUM BROMIDE

用金相显微镜,扫描电镜及能谱分析详细研究了中央空调机组吸收器使用TP2磷脱氧紫铜换热管开裂泄漏的原因.结果表明,紫铜管上的裂纹是应力腐蚀裂纹.裂纹是在紫铜管表面的残余应力和含氧溴化锂溶液的综合作用下发生的.含氧条件下,溴离子会引起点蚀而促进应力腐蚀开裂.验证试验再现了裂纹的产生.

Absorbers of central air-conditioning units used by clients in factory A and factory B are made of pure copper tubes. After running for more than one year or even before formal usage, many cracks were found on the surfaces of these exchanger tubes. The reason for cracking was investigated by using optical microscope, scanning microscope and Energy - Dispersive X-ray spectroscopy （EDX）. Results revealed that the cracks on the tubes was caused by stress corrosion cracking , which was the result of joint action of residual stress and lithium bromide solution containing oxygen. Under the condition of existence of oxygen, bromine ion can induce pitting and promote stress corrosion cracking. Validating tests reproduced the appearance of cracks.