Numerical simulation on flow and heat transfer characteristics in shell side of outward convex corrugated double-pipe heat exchangers

The flow and heat transfer mechanism in the shell side of corrugated double-pipe heat exchanger are studied numerically based on the k-ε model. The independent analysis of first layer thickness and main flow region grid are carried out using hexahedral mesh in the whole region combined with dense mesh in the corrugation region. Compared the data from empirical formula with computational results, the accuracy of numerical methods is verified. The strengthening heat transfer mechanism is revealed by analyzing the difference of the flow and heat transfer parameters distribution (speed, temperature and turbulent kinetic energy and turbulence dissipation rate) between corrugated tube and smooth tube. Meanwhile, the local Nusselt numbers and pressure drop distributed law along the corrugation wall is also analyzed. The results indicate that the detached vortex formed at the downstream side of corrugation which resulting in an obvious effect of heat transfer augmentation destroys the velocity and temperature boundary layer meanwhile increase the frictional resistance and thermal diffusivity.