DESIGN AND PRINTABILITY EVALUATION OF HEAT EXCHANGERS FOR LASER POWDER BED FUSION PROCESS

The structural design and additive manufacturing (AM) of cross-flow heat exchangers (HXs) are studied. A unit-based design framework is proposed to optimize the channel configuration in order to improve heat exchange performance (HXP) and meanwhile control pressure drop (PD) between the fluid inlet and outlet. A gradient-based optimization methodology is employed to drive the iterative design process. Both shape and topology changes are observed during the channel configuration evolution. Moreover, AM printability evaluation is considered and some re-design work is proposed with respect to metal laser powder bed fusion (LPBF) process. For an original optimized structure from the unit-based design, corner rounding operation is adopted first, specifically to avoid sharp features. Then the building process of the entire cross-flow HX containing the top, bottom caps, surrounding walls and the optimized thin-walled channels is simulated, and residual deformation is predicted through the sequential layer-by-layer analysis. Based on residual deformation profile, geometrical compensation is implemented for the 3D reconstructed model to reduce geometrical inaccuracy of the printed HX. Finally, a mature design scheme for cross-flow HX can be achieved as the solution that leads to largely improved HXP (e.g., nearly 200% increase), well controlled PD and enhanced printability with respect to the LPBF AM process.