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Study of corrosion and its control in aluminum solar collectors. Progress report, September 1, 1977--March 31, 1978

Technical Report ·
DOI:https://doi.org/10.2172/6563670· OSTI ID:6563670

Aluminum solar heat collectors operating on water/glycol heat transfer fluids are potentially attractive but for the critical problem of aluminum corrosion. A non-destructive electrochemical technique (linear polarization resistance method) was developed to determine the overall corrosion rate under various conditions. It was concluded that uninhibited ethylene glycol solutions most probably will cause catastrophic plant failure when used as a heat transfer medium in an aluminum solar collector system. The linear polarization resistance method and the pit depth measurement technique are used to evaluate the corrosion problems. In addition, a thin foil test method and an aluminum circulation panel (with a heat rejecting surface) were developed and successfully applied. The effects of using chemical scavengers for contaminants were also investigated. Also included are: (a) an investigation of the performance of the inhibited solution at high temperature (T > 100/sup 0/C), (b) an extension of the work to propylene glycol solutions, (c) the verification of the cube root law, and (d) the determination of the parameter a. An extensive literature review showed that phosphates, borates, nitrates, silicates and sodium mercaptobenzothiazole are the effective corrosion inhibitors used in ethylene glycol solutions.

Research Organization:
Giner, Inc., Waltham, MA (USA)
OSTI ID:
6563670
Report Number(s):
COO-2934-6
Country of Publication:
United States
Language:
English