Biodegradable, frost proof heat-transfer fluid, use thereof in near-surface geothermal installations, and a concentrate for preparing same

摘要

Biodegradable, frost proof heat-transfer fluid, use thereof in near-surface geothermal installations, and a concentrate: subject matter of the present invention is the use of a triazole-free composition which as well as water comprises a) 9.2% to 49.5% by weight of at least one C2 to C3 alkylene glycol, C2 to C3 polyalkylene glycol or glycerol, b) 0.1% to 4% by weight of at least one corrosion inhibitor, with the provisos that c) the composition is readily degradable biologically in accordance with test method OECD 301 A, d) the composition has an anaerobic biodegradability of at least 75% in accordance with test method OECD 311, e) the corrosion inhibitor or all corrosion inhibitors used are readily degradable biologically in accordance with OECD 301 A (for water-soluble corrosion inhibitors) or OECD 301 B (for corrosion inhibitors of low water-solubility), in near-surface geothermal installations as a heat-transfer fluid.

主权项

1. A process for operating a near-surface geothermal installation, comprising the step of bringing about the transfer of thermal energy with a triazole-free composition which, as well as water, comprises
a) 9.2 to 49.5% by weight of at least one C2- to C3-alkylene glycol, of a C2- to C3-polyalkylene glycol or glycerol, b) 0.1 to 4% by weight of at least one corrosion inhibitor, in which the corrosion inhibitor is an alkali metal, alkaline earth metal or amine salt of a compound of the formula where R1 is branched C6-C13-alkyl, or C5- or C6-cycloalkyl or polycycloalkyl having 6 to 13 carbon atoms, which may be substituted by one or two C1-C4-alkyl groups, R2 is hydrogen or C1-C6-alkyl and R3 is C1-C11-alkylene in a straight or branched chain, with the provisos that
c) the composition has good biodegradability (is “readily degradable”) according to test method OECD 301 A,d) the composition has an anaerobic biodegradability of at least 75% according to test method OECD 311,e) the corrosion inhibitor or all corrosion inhibitors used have good biodegradability (are “readily degradable”) according to OECD 301 A (for water-soluble corrosion inhibitors) or OECD 301 B (for sparingly water-soluble corrosion inhibitors).