Drag‐reducing surfactants

Although drag reduction by polymers has become common practice for the pipeline transport of crude oil, drag reduction by surfactants for district heating or cooling has so far been applied only in Japan. Resistance to the adoption of this approach by the rest of the world is based on environmental concerns and the reduced capacity of heat exchangers that are all designed for turbulent flow. Newly developed types of drag‐reducing surfactants with improved biodegradability and the ongoing activity to find more suitable exchanger designs will, it is to be hoped, lead to a widespread use of this promising technology.