Design and Computational Evaluation of a Finned Heat Sink for Sub-Zero Additive Manufacturing (SZ-AM)

Sub-Zero Additive Manufacturing (SZ-AM) is a direct method for producing ice components by freezing water in a cryogenic environment. Thermal management is crucial in SZ-AM, as it deals with temperature ranges above freezing (water) and below freezing (ice). The SZ-AM process requires rapid and uniform cooling while operating at cryogenic temperatures, achieved through liquid nitrogen (LN2) cooling. The process involves jetting of water droplets onto a build platform, maintained at sub-zero temperature, to enable instant cooling and solidification. This research investigates the thermal design and computational simulation of a finned aluminium heat sink embedded in the build platform of an SZ-AM system. Rectangular aluminum fins are utilized to enhance convective heat transfer performance in extreme thermal gradients. The optimal design is considered for manufacturability, structural stability, and laminar flow of LN2 vapor. Analytical solutions are employed to determine performance parameters, including fin efficiency, heat transfer, thermal resistance, and effectiveness. The theoretical results reported a fin efficiency of 92.8%, accompanied by a significant decrease in thermal resistance from 0.50 K/W (unfinned) to 0.141 K/W (finned), and an effectiveness of 3.55. The results are computationally verified using ANSYS Fluent. The findings show that the finned design significantly enhances thermal performance and cooling uniformity of the build platform in SZ-AM environments. The integration of fin-based heat sinks into the build platforms forms a benchmark methodology for incorporating passive thermal management into future generations of cryogenic manufacturing technologies.