Patent ID: 7987866

Claim:
A method for reducing drag in a water-based liquid system flowing in conduits for the efficient distribution of heat or cold, which method consisting essentially of adding to the water-based liquid system a combination consisting essentially of a zwitterionic surfactant having the formula wherein R is a saturated or unsaturated aliphatic group with 10-24 carbon atoms, or a group R′NHC 3 H 6 — where R′ is the acyl group with 10 to 24 carbon atoms, R 6 and R 7 are independently of each other an alkyl group of 1-4 carbon atoms or an hydroxyalkyl group of 2-4 carbon atoms, and R 4 is an alkylene group of 1-4 carbon atoms; and an anionic ether surfactant having the general structure R 1 (OA) n B, R 1 O(AO) n C m H 2m D or R 3 NH(AO) n C m H 2m D or a mixture thereof, where R 1 is a hydrocarbon group of 10-24 carbon atoms, R3 is an acyl group of 10-24 carbon atoms, A is an alkylene group having 2-4 carbon atoms, n is a number from 1 to 10, m is 1-4, B is a sulphate group OSO 3 M and D is a carboxylate group COOM, in which M is a cationic group; wherein the weight proportion between the zwitterionic surfactant and the anionic ether surfactant is from 100:1 to 1:1; and wherein the water-based system is a heat-transfer medium with a temperature in the range of about 50° C. to about 120° C.