Claims
- 1. In a method of collecting solar energy involving the use of concentric conduits wherein a heat transfer fluid flows through the inner conduit and a relatively low vacuum is maintained in the annulus between the conduits, the improvement of using a heat transfer fluid composition comprising a blend of about 5-30% biphenyl, 25-75% diphenyl oxide, 10-50% ortho-terphenyl and 5-25% meta-terphenyl, said composition being substantially free of water and aryl compounds having alkyl substituents and maintaining by its thermal stability at temperatures of at least 350.degree.-400.degree. C. and pumpability at temperatures of -10.degree. C. or lower.
- 2. In a method of collecting solar energy involving the use of concentric conduits wherein a heat transfer fluid flows through the inner conduit and a relatively low vacuum is maintained in the annulus between the conduits, the improvement of using a heat transfer fluid composition comprising a blend of about 5-15% biphenyl, 45-75% diphenyl oxide, 15-45% ortho-terphenyl, and 5-20% meta-terphenyl, said composition being substantially free of aromatic compounds having alkyl substituents such that the fluid has a hydrogen permeation rate of less than about 6.times.10.sup.-4 1-torr./hr cm.sup.2 as determined by the Hydrogen Permeation Test.
- 3. A method of claim 1 wherein the ratio of biphenyl to ortho-terphenyl to meta-terphenyl is 30.9:47.5:21.6.
- 4. A method of claim 1 wherein the heat transfer fluid composition comprises a blend of from about 10% to about 23% biphenyl, from about 25% to about 65% diphenyl oxide, from about 16% to about 35% ortho-terphenyl and from about 7% to about 16% meta-terphenyl.
- 5. The method of claim 1 wherein the heat transfer fluid contains at the most 2000 ppm of aryl compounds with alkyl substituents.
- 6. The method of claim 2 wherein the heat transfer fluid contains at the most 2000 ppm of aryl compounds with alkyl substituents.
Prior Application
This is a continuation of application Ser. No. 280,601, filed Dec. 8, 1988, which is a continuation-in-part of application Ser. No. 160,554, filed Feb. 25, 1988, now abandoned.
US Referenced Citations (13)
Foreign Referenced Citations (3)
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Aug 1985 |
DEX |
8907634 |
Aug 1989 |
WOX |
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Non-Patent Literature Citations (4)
Entry |
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Johns et al., "Thermal Stability of Organic Compounds", I & EC Product Research and Development, pp. 2-6, 1962. |
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Continuations (1)
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Number |
Date |
Country |
Parent |
280601 |
Dec 1988 |
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
160554 |
Feb 1988 |
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