Study of the Influence of Turbulence Models on Hydrodynamic and Thermal Parameters of Heat Carriers in Calculations of Heat Exchangers

In this paper, the heat exchange processes between a cold (oil) and a highly heated (water) heat carrier in a“tube-in-tube” type heat exchanger with a parallel flow scheme are studied using semi-empirical turbulencemodels: k-ω SST, k-ε, and Transition SST. The analysis of the obtained results showed that the k-ω SSTturbulence model was more preferable for the calculation of a heat exchanger with a sufficiently small tubediameter, because of the effect of the boundary layer in the tube. This turbulence model more pronouncedlyreproduces the laminar-turbulent transition, which is carried out in these processes, where the viscosity of oilstrongly depends on temperature. Finite difference and finite volume methods were chosen for numericalmodelling and calculation of heat exchange processes. The calculations were carried out on the basis ofComputational Fluid Dynamics, using the Ansys Fluent. The RANS equations closed by means of thegamma-Retheta turbulence model, which takes into account the laminar-turbulent transition and the k-ω SSTmodel equations, were used for numerical modelling of coolant hydrodynamics. Based on the proposedturbulence model, the distributions of hydrodynamic and thermal parameters and similarity criteria (Re, Pr,Nu) of the process along the length of the tube are obtained.