DRAG REDUCTION AND HEAT TRANSFER ENHANCEMENT OF WATER FLOW IN A PIPE USING NEW SURFACTANTS FOR ENVIRONMENTALLY ACCEPTABLE DRAG REDUCING ADDITIVES

The drag reduction of a water flow with new drag reducing surfactants (mixture of amine oxide nonionic type surfactants and imidazolium betaine amphoteric type surfactants) which were selected as environmentally acceptable drag reducing additives was investigated experimentally. The flow resistances of the water flow with two kinds of surfactants were markedly reduced as compared with that of a water flow with only amine oxide under the conditions of cold water and hot water supplies, respectively. The heat transfer enhancement experiments were carried out using spring coil which was inserted in the test circular tube as a turbulence promoter. As a result, it was observed that heat transfer coefficient of the water flow with N-stearyl-NN-dimethylamine oxide using the spring coil increased up by about four times as compared with that without the spring coil. Useful non-dimensional correlative equations for flow resistance and heat transfer were derived by various non-dimensional parameters.