Evaluation of surfactant drag reduction effect in a district heating system

A scale-up method proposed by Hoyt was used to evaluate the flow resistance of working fluid in a district heating system (DHS) after a surfactant drag reducer, CTAC/NaSal, was added. The measured drag reduction data of 100ppm surfactant solution obtained from an 18.5mm diameter pipe in the laboratory were used for the evaluation. The results show that the reduction of the pressure drop in the system reaches 23.28 by the addition of surfactants, indicating a very good energy saving effect and application prospective. Comparing with the effect of 100ppm solution, it is found that the drag reduction will not be further improved obviously in the system with increasing concentration. It was also found that the local pressure drop takes a large proportion in the total pressure drop of the DHS, which could not be reduced by adding the surfactants.