Study of aluminum corrosion in aluminum solar heat collectors using aqueous glycol solution for heat transfer. Annual technical progress report, July 30, 1979-July 31, 1980
The effects of glycol aging at elevated temperatures over long periods of time were studied and the zinc powder protective technique was optimized. Glycols are known to gradually decompose into organic acids at high temperatures. These product species may be aggressive to aluminum in the long run. In addition, corrosion inhibitors may also breakdown due to continuous exposure to high temperatures. As for the zinc powder protective technique, efforts have been made to determine the optimal conditions under which aluminum solar collector panels can be protected most effectively and economically. Both uninhibited and inhibited ethylene as well as propyleneglycols have been aged at three different temperatures (100, 140, and 190/sup 0/C) for 6000 hours continuously. Aliquot samples were taken at 1000 hour intervals for pH measurement and chemical analysis. Results showed that in most cases solution pH dropped sharply during the first 1000 hours of exposure and gradually decreased at a slower pace as the aging process progressed. It was also noted that higher temperatures appeared to hasten this pH shift. The corrosiveness of these aged glycol solutions towards aluminum was determined based on laboratory corrosion tests. The critical pitting potential (E/sub p/) of aluminum in chloride-ion containing aqueous glycol solutions was determined. Its dependence on temperature, chloride-ion concentration, and glycol content was investigated in detail. E/sub p/ was found to become more negative with higher chloride-ion concentration, increasing temperature, and decreasing glycol content. (MHR)
- Research Organization:
- Giner, Inc., Waltham, MA (USA)
- DOE Contract Number:
- AC04-79CS31072
- OSTI ID:
- 5210042
- Report Number(s):
- DOE/CS/31072-T2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALUMINIUM
CORROSION
GLYCOLS
CORROSIVE EFFECTS
AQUEOUS SOLUTIONS
CORROSION INHIBITORS
HEAT TRANSFER FLUIDS
POWDERS
SOLAR COLLECTORS
TEMPERATURE DEPENDENCE
ZINC
ALCOHOLS
CHEMICAL REACTIONS
DISPERSIONS
ELEMENTS
EQUIPMENT
FLUIDS
HYDROXY COMPOUNDS
METALS
MIXTURES
ORGANIC COMPOUNDS
SOLAR EQUIPMENT
SOLUTIONS
141000* - Solar Collectors & Concentrators