Performance Evaluation of hi-k Lung-inspired 3D-printed Polymer Heat Exchangers

Abstract

Polymer heat exchangers are attractive thermal management solutions due to their low-cost, lightweight, antifouling, and anti-corrosion characteristics. They, however, demonstrate poor thermal characteristics mainly due to the low thermal conductivities of typical polymers. Additive manufacturing of high thermal conductivity polymer heat exchangers utilizing complex heat transfer topologies could potentially address the issue. In this study, thermal performances of 3D-printed polymer heat exchangers with intricate internal geometries including a lung-inspired design at low-to-high thermal conductivities are experimentally and numerically examined. It was found the effective thermal conductivity of a 3D-printed polymer heat exchanger is close to the through-plane thermal conductivity. It was also identified that through-plane leakage in thin 3D-printed polymer walls is a major challenge associated with 3D-printed polymer heat exchangers. The issue was remedied by in-situ infusion of an epoxy layer during the 3D-printing and a post-curing process. Experiments conducted at various thermo-hydraulic conditions showed that the high thermal conductivity lung-inspired polymer heat exchanger offers high thermal duties at reduced pressure drop penalties and exceptionally high effectiveness of 70–80% that is comparable to that of metal-based heat exchangers. At an air Reynolds number of 1200, the volume-based power density of the high thermal conductivity lung-inspired design is 522 kW/m3, which is a 101% improvement compared with a typical plate-and-frame design. This study concludes that the thermal performance of a polymer heat exchanger strongly depends on both material (i.e., thermal conductivity) and architecture (i.e., an optimum design with a minimal thermal resistance between hot and cold sides). Insights gained from this study could offer new pathways for designing innovative 3D-printed polymer heat exchanger technologies with unprecedented heat transfer rates at reduced pressure drop penalties for lightweight, antifouling, and/or anti-corrosion applications.