Microencapsulated Salt Hydrate Based Filaments for FDM 3D Printing

Building energy consumption for heating and cooling accounts for a large portion of energy usage and CO2 emissions in our country. Thermal energy storage (TES) materials (such as phase change materials (PCMs)) have the potential to increase a building’s thermal mass and provide flexibility to time‐shift demand. Hence, PCMs can be used to reduce demand changes, take advantage of time‐of-use rates, better match distributed generation output, or improve efficiency of the building and the grid. Despite these potential advantages, PCMs have not been widely adopted due to high cost, susceptibility to combustion, low heat transfer properties and relatively low volumetric energy density. Through collaboration with the National Renewable Energy Laboratory (NREL), TCPoly, Inc. will utilize 3D printing to create low-cost, durable, and high-energy-density structures for thermal energy storage in buildings. The technology is based on microencapsulated inorganic salt hydrate PCMs that are encapsulated in thermally conductive polymers (TCPs) and maintain encapsulation through the 3D printing process. 3D printing enables large-scale 3D printed objects that maintain domain control of PCM and TCP compositions on the micron scale, thus improving the performance of salt hydrate PCMs (reduced supercooling, increased thermal conductivity and cycle lifetime). Moreover, by enabling the use of low-cost filament-fed fused deposition modeling (FDM) 3D printers, complex phase change heat exchanger geometries can be fabricated to enhance and control charge and discharge rates. This proposal will result in the first commercially available high-performance TES material that can be manufactured through the simple and relatively low-cost FDM 3D printing method. Therefore, the proposed material will serve as a platform technology that can be used for both thermal energy storage and thermal management applications across a multitude of industries.