2006 Volume 55 Issue 7 Pages 312-319
Air leakage is considered as a main factor of the troubles in absorption refrigerator. In this study, accelerated corrosion tests simulating air leakage have been conducted using 20 RT absorption refrigerator with air leak system. As a function of air leak speed, changes of dissolved oxygen levels and corrosion product concentrations (ion and oxide) of copper and carbon steel have been measured both in LiBr coolant and refrigerant.
In addition, the effects of temperature and concentrations of dissolved oxygen and copper ion on corrosion potentials of carbon steel were investigated in LiBr solutions containing various inhibitors. From anodic polarization curves of carbon steel, pitting potentials were determined at various temperatures. From the relationship between corrosion potentials and pitting potentials, accelerating factors of corrosion damage of carbon steel were considered.
From above investigations, a model of acceleration process of carbon steel corrosion by air leakage has been proposed as follows.
(1) Copper ion dissolves into LiBr coolant by air leakage
(2) Corrosion potentials of carbon steel shift noble near the pitting potentials by the combination effects of dissolved oxygen, copper ion and inhibitors.
(3) Corrosion potentials of carbon steel exceed the pitting potentials only in special combinations of dissolved oxygen, copper ion and inhibitors.