Microvascular Composites for Novel Thermal Management Devices

ABSTRACT: Living systems rely on pervasive vascular networks to enable a plurality of biological function, exemplified by natural composite structures that are lightweight, high-strength, and capable of mass and energy transport. In contrast, synthetic composites possess high strength-to-weight ratios but lack the dynamic functionality of their natural counterparts. CU Aerospace, with team partners the University of Illinois at Urbana-Champaign (UIUC), North Carolina State University (NCSU), and Lockheed Martin, propose to use a revolutionary microvascular technology developed at UIUC to build a composite counter-flow heat exchanger. This technology relies on 3D weaving of sacrificial fibers into a polymeric matrix, which are subsequently vaporized to obtain a uniform array of capillaries. By weaving these sacrificial fibers with a perpendicular array of carbon fibers and using computational modeling to optimize the design, this device can achieve good lateral thermal conductance while retaining very low axial conductance. Most Joule-Thomson heat exchangers are either metal finned-tube devices with limited surface area between the solid and gas streams, or etched-glass/silicon devices that allow relatively limited gas flow and cooling power. A micro-capillary array based heat exchanger offers the potential for both large surface area and large gas flow, with a manufacturing process that offers low-cost mass production. BENEFIT: Development of the sacrificial fibers to allow incorporation of microvascular networks in polymeric composites has tremendous potential. Multiple functionalities are achieved by distributing different fluids throughout the microvascular network, which can be seamlessly integrated into both rigid and flexible materials. By circulating fluids with unique physical properties, there is the capability to create a new generation of biphasic composite materials in which the solid phase provides strength and form while the fluid phase provides interchangeable functionality. Applications that have been examined include self-healing, thermal management, electromagnetic signature, electrical conductivity tuning, and chemical reactivity. The impact of this technology is extremely broad and far-reaching, while our initial efforts are focused on military and aerospace applications; fertile research opportunities exist across a broad cross-section of industries. Long-term strategic plans are to leverage our development efforts to foster spin-off technologies in related industries.