Modeling flow and heat transfer in pipes with turbulators for advanced heat exchangers with high and very high (from a million to a billion) Reynolds numbers

Abstract

Objective. The paper considers the solution of the heat transfer problem for flow turbulators with a semicircular cross-section using multiblock computational technologies based on the solution of Reynolds' equations (closed for the transient regime using Menter's shear stress transport model) and the energy equation (on intersecting structured grids of different scales) by the factorized finite volume method (FVM).

Method. The paper uses computational methods to mathematically model heat transfer in pipes with turbulators for viscous coolants at very high (up to a billion) Reynolds criteria, characteristic of developed turbulent flow regimes.

Result. The calculations were performed using a theoretical method based on the solution of Reynolds' equations by the factorized finite volume method, closed for transient regimes using Menter's shear stress transport model, and the energy equation on intersecting structured grids of different scales (FVM). Using the FKOM method, both local and average flow and heat transfer characteristics were obtained in pipes with turbulators for a viscous coolant for a developed coolant flow regime. This allowed us to determine heat transfer intensification levels for these regimes.

Conclusion. Heat transfer intensification in air is postulated for high millionth O. Reynolds criteria, which is potentially relevant for channel flows in heat exchanger channels, with noticeable increases in hydraulic resistance and can increase relative to reduced O. Reynolds criteria for large relative protrusions d/D = 0.90. It was formulated that for billionth O. Reynolds criteria, channels with protrusions are inferior to channels with roughness in terms of heat transfer intensification, since there is a lower level of heat transfer intensification with approximately the same increase in relative hydraulic resistance.