The surface properties of vegetable oils are investigated. It is shown that the investigated vegetable oils at the interface between the liquid-gas, liquid-solid surfaces, liquid-liquid behave as surface-active substances for milk. It is shown that the hydromechanical characteristics of milk are changing, which moves in the pipeline or apparatus, namely in the boundary layer under the influence of plant surface-active substances (surfactants). It is shown that the reduction of the surface tension coefficient minimizes the thickness of the boundary layer A in the system wall of the pipeline-milk, which means that it increases the average flow velocity in it and as a consequence, such a system is capable of effectively transmitting the amount of heat. A numerical range of the surface criterion for milk was found for adding surfactants.
vegetable oils, average thickness of the laminar boundary layers, surface number, surfactants, coefficient of surface tension
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