Significance of shear induced structure in surfactants for drag reduction

 Cationic drag reducing surfactants are suitable means for reducing the energy costs in city district heating and cooling systems. Water used in these systems is usually a treated water, however, the loss of water due to the leakage is often supplied by water from the municipal network and thus the content of ions in the system may increase. That is why the influence of ions present in water and temperature on viscosity curves has been investigated and the effect of both on Shear Induced Structure (SIS) is shown here. We have proved that SIS is not an indispensable condition for the surfactant ability of drag reduction. Received: 7 August 1997 Accepted: 29 April 1998