Intentional mechanical degradation for heat transfer recovery in flow of drag-reducing surfactant solutions

Temporary intentional mechanical degradation of surfactant solutions was investigated as a method of heat transfer recovery for heat exchangers installed in recirculating systems where surfactant solutions are used as drag-reducing additives. Heat transfer recovery is particularly important for implementation of the drag reduction technology in systems such as buildings or district heating and cooling. We studied and quantified the degradation and subsequent recovery processes associated with this heat transfer recovery technique, and the strong effect of fluid temperature on recovery. Some of the important issues for successful implementation of the approach studied here include also the efficiency of the degradation devices and the optimization of the relevant properties of surfactant solutions, which are both needed to achieve maximum overall drag reduction in the system while still maintaining sufficient heat transfer in the exchangers. These results and the concepts related to heat transfer recovery in heat exchangers are discussed in terms of practical implementation considerations and in light of the results from an associated field test conducted in a hydronic cooling system in a building. (C) 2017 Elsevier Inc. All rights reserved.