Numerical modeling and calculation of heat transfer between heat carriers in heat exchangers

Heating of oil and oil products is widely used to reduce energy loss during transportation. An approach is being developed to determine the effective length of the heat exchanger and the temperature of the cold heat carrier at its outlet in the case of a strong dependence of oil viscosity on temperature. The oil of the Uzen field (Kazakhstan) is considered as a heated heat carrier, and water is considered as a heating component. The method of the average-logarithmic temperature difference, modified for the case of variable viscosity, and methods of computational fluid dynamics are used for calculations. The results of numerical calculations are compared with the data obtained on the basis of a theoretical approach at constant viscosity. When using a theoretical approach with constant or variable viscosity, the heat transfer coefficients to cold and hot heat carriers are found using criterion dependencies. In the case of variable oil viscosity, the transition of the laminar flow regime to the turbulent one is manifested, which has a significant effect on the effective length of the heat exchanger. To solve this problem comprehensively, a mathematical model of hydrodynamics and heat transfer of heat carriers has been developed and multiparametric numerical calculations have been performed using the “Ansys Fluent” software package.