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The forces acting on the elementary volume of liquid in the pipeline in the laminar boundary layer are considered. A new dimensionless complex the surface number and the concept of the turbulence coefficient laminar boundary layer is proposed. The calculation of Froude, Euler numbers, the inverse Reynolds number and the surface number in laminar boundary layer for water under normal conditions is given. It is shown that the Froude number and the inverse Reynolds number are 4-5 orders of magnitude smaller than the surface number and Euler number in laminar boundary layer, which allows neglecting the forces of gravitation and friction in these conditions. Equations are proposed for calculating the average thickness of laminar boundary layer. The dependence of the surface number on the coefficient of surface tension of the refrigerant is obtained. It is shown that a decrease in the surface tension coefficient minimizes the average thickness of the laminar boundary layers in the wall system of the pipeline and liquid and increases the average velocities of the coolant flows in these layers, as a result of which such a system is capable of more efficient transfer of heat. It is substantiated and experimentally confirmed that at optimum concentrations of surfactants, the values of the surface number are minimal.

Modeling the interaction of coolant flows at the liquid-solid boundary with allowance for the laminar boundary layer