Additive Manufacturing of Compact Manifold-Microchannel Heat Exchangers Utilizing Direct Metal Laser Sintering

Abstract

Direct Metal Laser Sintering is a metal additive manufacturing technique which uses a laser to fuse metal powders, layer by layer to form a 3D object. In this study, Direct Metal Laser Sintering is used to fabricate compact high temperature manifold-microchannel heat exchangers. Compared to the state of the art heat exchangers, manifold-microchannel heat exchangers have been proven to yield superior performances. However, fabrication of manifold-microchannel heat exchangers using conventional fabrication methods is a challenge due to their complex geometry. Additive manufacturing processes, like Direct Metal Laser Sintering, allow fabricating the manifold-microchannel heat exchanger as a single component, which significantly simplify its production process. In order to fully utilize the performance potential of manifold-microchannel heat exchangers, small fins (0.1-0.2 mm) and channels (0.2-0.3 mm) are required. In this study, three different machines were used to study the effect of geometries and printing parameters, such as laser power, powder size, and layer thickness, on the fins and channel size of the fabricated microchannel heat exchangers. A comprehensive study has been performed to achieve fin thickness as small as 0.110 mm. Pressure containment tests were also performed to evaluate the minimum base thickness that can hold the designed pressure. A 3"×3"×3" size microchannel heat exchangers was then successfully fabricated with straight fins of 0.133 mm out of Maraging Steel, and a 4"×4"×4" size microchannel heat exchangers was successfully fabricated with fin size of 0.22 mm out of Inconel 718. The results thus pave the way for more advancements in optimized additive manufacturing of next-generation heat exchangers.