Geometrical Analysis of Heat Transfer in a Corrugated Channels Heat Exchanger under Forced Convection and Turbulent Flow

This study presents a numerical investigation of a steady, two-dimensional, incompressible turbulent flow with forced convection along a small channel with corrugated walls in a trapezoidal shape. The objective of this study is to evaluate the effect of corrugation geometry on the heat transfer rate and pressure drop through the channel. The constructal design method was applied to the geometry domain with two constraints: the total area of the channel and the area of the trapezoidal corrugation upstream of the channel. Two degrees of freedom are considered: the ratio of the smaller base to the larger base of the upstream trapezoidal corrugation (LA₂/LA₁) and the ratio of the trapezoid’s height to its larger base (H₁/LA₁). All cases were simulated for convective flows with Reynolds and Prandtl numbers of Re_D = 22,000 and Pr = 0.71, respectively. The time-averaged mass, momentum, and energy conservation equations are solved using the Finite Volume Method with the RANS (Reynolds-Averaged Navier-Stokes) turbulence model and the k-ω SST (Shear Stress Transport) turbulence closure model. The results indicate that a specific H₁/LA₁ ratio improves the heat transfer rate by 26.2% compared to the worst case for the same LA₂/LA₁ ratio. Furthermore, larger insertions of trapezoidal corrugations at the bottom of the channel enhance the thermal performance of the heat exchanger, while the insertion of corrugations at the upper part of the channel has a negligible effect on heat transfer performance. From a fluid dynamic perspective, smaller insertions in the fluid flow direction led to lower pressure losses.