Drag reducing surfactants for district heating

An application of specific surfactants in district heating and cooling systems can give notable economical benefits due to a reduction in friction and heat transfer attributed to a formation of an additional viscous sublayer along the pipe walls, buffering the turbulence. A mathematical three-layer model of water velocity profile is composed for the calculation of drag reduction and flow-capacity increase. At a properly chosen surfactant and concentration, the local drag can be reduced up to 80%. A computer simulation and optimization for a selected district heating network model with additive shows 4% saving in total costs because smaller pipes and weaker pumps are required.