Design of an innovative compact heat exchanger manufactured with additive manufacturing processes using TPMS

In the framework of human space flight, the active control of temperature inside crewed modules assumes paramount importance in protecting the habitable environment from the harsh thermal conditions of outer space. The need to actively remove the heat from the module is met through suitably sized heat exchangers, as part of the Active Thermal Control Subsystem (ATCS). This study carried out in collaboration with Thales Alenia Space Italia, concerns the conceptual design of a Triply Periodic Minimal Surfaces (TPMS) Compact Heat Exchanger (CHX), for space applications, to be used with two streams of 3M Novec HFE 7200 DL in the temperature range from -50 to 6.5 °C. The proposed design is the result of a wide parametric analysis of different possible configurations. It is a modular CHX with 9 modules in a 3×3 arrangement, manufactured in aluminum AlSi10Mg and based on prismatic gyroids, in which hot and cold fluids flow in counter currents in a turbulent regime. The performance of the proposed design, being peculiarly suited for Additive Manufacturing production, has been checked by an extensive Computational Fluid Dynamics analysis, where the 3D conjugate heat transfer problem has been solved with the commercial software in STAR-CCM+ relying on the LAG EB k-ε turbulence closure. Both the computed pressure drop and outlet temperatures turned out to be compliant with the design constraints. Concerning the weight, the printing of the aluminum component (AlSi10Mg), compared to the use of steel, allows a weight saving of around 66% for the same design, ending in a total mass of 22 kg for the entire assembly. However, a factor of 3 overweight of the device is identified with respect to the target value and deserves some further optimization in the choice of the design and materials.