| This is a study of fluid mechanics and heat transfer of surfactant water solutions, which exhibit drag reduction in the turbulent flow (when compared to pure water). The stress is placed on those aspects of flow and heat transfer behavior of drag reducing solutions which are relevant for application in closed circulation loops (for the purpose of savings of pumping power), like hydronic cooling and heating systems in buildings. Most of the tests are done with the same solution of the cationic surfactant ETHOQUAD T13 in concentration of 2300 ppm, plus 2000 ppm sodium salicylate as counter ion, at the temperatures close to the room temperature.; The following are the main problems studied: diameter effect, fluid characterization (drag reducing ability and capillary viscometry), different types of degradation (permanent and temporary), thermal and hydrodynamic flow development in the entry region, flow through an elbow, heat transfer in different heat exchangers, heat transfer enhancement, effect on pumps and valves, corrosion of standard building materials when exposed to the surfactant solution and disposal of used surfactant solution. We feel that all of the problems studied are understood and solved satisfactorily so that field test can be done. Despite encouraging results with inserts for heat transfer enhancement, reduced heat transfer in heat exchangers can be singled out as the most serious problem for successful application in circulation loops, which still requires more tests. |
