Numerical investigation of the heat transfer in a meandering millichannel by a coupled 1D-flow-channel / 3D-surrounding-solid model

Abstract

Heat exchanger/reactors with corrugated channels are used to implement especially exothermal chemical reactions. Heat conduction effects in their solid material are not negligible and induce in particular heat flows between adjacent channels. In this context, this work proposes a model of a plate-type heat exchanger/reactor with a 2D-meandering millichannel, taking into account these conduction effects by coupling a 1D approach for the channel flow, with correlations for the friction factor and the Nusselt number, to a 3D approach for the solid part. This model is a compromise between the 1D classical reactor models that don’t account for 3D conduction effects in the solid and the 3D simulations of the channel flow with the surrounding solid which are computationnally expensive or unachievable for a large reactor. In the tested case, the 1D/3D and 3D CFD results are in good agreement (5 min vs 4 h computational time), which suggests valid model assumptions and internal model consistency. Simulated and experimental conversion rates of a fast highly exothermic reaction are then compared, showing the relevancy of the model. Further investigations are performed to highlight the effect of conjugate heat transfer in millistructured heat exchangers and to quantify its limitations versus the 1D/3D model.