Recovery of surfactant-induced friction reduction in a closed hot water system.

Abstract

In the 1980's the use of surfactants to decrease pumping energy requirements in district heating systems was explored in Europe. FRAs are particularly attractive for district energy systems because they have long pipe runs and the associated pumping costs can be a large component of total operating costs. In this research project, a series of obstructing devices were designed and tested for their ability to disrupt micelles and reverse the friction reducing effect in a 3/4 inch diameter stainless steel experimental test loop. Four simple obstructing geometries were investigated: a central obstruction blocking one quarter of the flow area, a central obstruction blocking half of the flow area and two obstructions which blocked the area close to the pipe wall, blocking one half and three quarters of the flow area, respectively. The experimental friction reducing additive was a combination of a quaternary ammonium surfactant, Ethoquad O/12, and a 3-hydroxy-2-naphthoate counterion, at concentrations of 1600 ppm and 800 ppm respectively. The obstructions were tested at three temperatures, 70, 50 and 40 Celsius and at flow rates of 3.7, 3.0 and 2.0 m./s. (Abstract shortened by UMI.)