Integrated thermo-hydraulic heat exchanger modelling for additive manufacturing optimisation

The design of optimized Heat Exchangers (HE) represents a key asset in the effort towards transport decarbonization and hydrogen-powered electrification due to the low temperatures required for batteries and high amounts of low-grade waste heat produced by fuel cells. At the same time, advancements in the field of Additive Manufacturing (AM) offer new opportunities for unprecedented geometries: enhancing heat transfer, minimising mass and improving compactness. Within this paper, a new methodology is proposed for the modelling of the thermal-hydraulic performance of compact heat exchangers fabricated via AM. Focus is placed towards the realization of a robust and computationally inexpensive tool for evaluating the performance of a wide range of AM heat exchanger geometries for use in multi-objective optimisation. The methodology is based on flexible physics-driven formulations and extensive model parametrization. The proposed approach is verified against experimental data from the literature, exhibiting accurate heat transfer simulation, with a maximum error of 3.7% with respect to the fluids’ temperature changes. Initial simulations based on current state-of-the-art models showed significant underestimation of the fluids’ pressure drops, of up to -26.4%, when they are applied to AM HEs. However, adjusting the channels’ diameter according to the formation of melting dross, is shown to reduce the maximum hydraulic losses underestimation to just -11.4%. Alternatively, the definition of a calibrated penalty factor, conservatively applied to conventional formulations, allows for the maximum pressure drops to be underestimated by only -4.3%, instead.