Modelling of a Compact Heat Exchanger With TPMS Geometry

Abstract A method for the full aerothermal analysis of a compact heat exchanger with an internal TPMS (Triple Periodic Minimal Surface) is presented in this paper. The proposed methodology simplifies and sub-models the geometry, allowing for a reduction in computational costs during the design phase. The steps to follow are the estimation of the aerothermal characteristics of the TPMS basic cell unit, the porous media approximation for both fluids flowing through the TPMS lattice, and the dual cell heat exchanger model for the heat transfer between the two fluids. The model assumes both fluids in laminar regime and high Prandtl numbers, corresponding to a current aeronautical application. The geometry tested and presented herein is a simplification of a real one, with a number of TPMS cells ∼O(100), one order of magnitude lower than the true heat exchanger, ∼O(103–104), with the aim of testing the methodology. The use of a simplified geometry allows comparing the results against a conjugate model, which comprises the CFD simulation of the hot and cold fluids and the solid simulation of the heat exchanged through the TPMS core and casing. Reliable estimations of the pressure drops and temperature changes are achieved. The sub-modelling approach reduces the meshing time to only 2.8% of that of the conjugate model, and, for the same case, the running time is shortened to 32% of the original time. Therefore, the presented methodology can be employed as a tool in the iterative design process of a heat exchanger with a complex internal geometry.