Session: Government Agency Student Posters

Paper Number: 173493

Rapid Thermoelectric Energy Harvesting Optimization via Additive Manufacturing With Numerical Methods 

The thermal energy loss present in mechanical and electrical systems results can be harvested by thermoelectric materials to generate electricity via the Seebeck effect and thus contribute to clean-energy systems through the use of thermoelectric materials (TE). However, the thermal gradient in traditional thermoelectric generators (TEGs) tends to decrease over time, usually retaining only 20–30% of its peak value after stabilization. Though a passive heat sink to TEGs can alleviate the rapid decrease in thermal gradient, there is a need to fabricate more robust and efficient solutions to sustain optimal performance over extended periods. Previous literature has confirmed the positive effects of a variety of metamaterial architectures for improving TEG gradient sustainability. Additive manufacturing enables rapid manufacturing with a high degree of modularity and the creation of free-standing TEs in various complex geometries, thus increasing the potential for thermoelectric voltage generation. For example, custom-made thermoelectric shields can be used to harvest heat produced by batteries and motors and generate a voltage to recharge or supplement a power source. This work focuses on formulating and testing a rapid, replicable additive manufacturing process of metamaterial architectures for TEGs using 3D-printed alumina (Al₂O₃). A DLP resin 3D printer (Phrozen Sonic Mini 8K) is used to test various resin processing methods (i.e. milling, magnetic mixing), dispersant agents and concentrations (BYK-111, BYK-022, BYK-2055, etc. at 2%-10%), and alumina concentration amounts (i.e. 50%, 60%, 70%) for the most optimized solution. The sample architecture involved six metamaterial designs of various complexity at a 5mm x 5mm x 5mm scale: two solid cubes, two 2D reentrant honeycombs, a 3D reentrant honeycomb, and an octet truss. Successful samples were composed of 70%wt alumina powder of 7 micrometers that is surface modified using polyvinylpyrrolidone, 15% poly (ethylene glycol)-diacrylate (PEDGA) and 15% vinylmethoxysiloxane homopolymer (VMM) as the resin matrix, and 10% of the dispersant BYK-111 to keep the alumina suspended. PEGDA has a high decomposition temperature (~250°C), and VMM prevents sample breakdown during pyrolysis. This slurry is processed in a milling machine (Retsch CryoMill) for 10 minutes at a frequency of 12 before 0.03% phenylbis(2,4,6-trimethylbenzoyl) phosphine oxide as the photoinitiator and 0.03% 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl) benzene as the photoscatterer to improve print resolution are added. Post-printing, samples are washed in isopropyl alcohol, then additionally UV cured for 10 minutes (Creality Wash and Cure Station). Samples are then treated with pyrolysis in a tube furnace at 1150°C for 4 hours at a heating rate of 600°C in the ambient atmosphere. Samples are coated with a 10 nanometer layer of gold (via a Hummer 6.2, Anatech Ltd., a plasma sputtering device) to provide electrical conductance for scanning electron microscopy (SEM) using a Tescan Vega 3, which is used to examine alumina bonding and layering and verify the final integrity. Throughout the manufacturing process, parameters such as size changes, print quality and resolution, and surface integrity; and flaws such as brittleness, delamination, and cracks are monitored to evaluate composition efficacy and identify problems with structural integrity. This study provides a way of manufacturing 3D-printable alumina-resin composites for metamaterial architecture. This method of manufacturing provides an avenue to explore other thermoelectric material 3D printing methods and opens up opportunities to improve the efficiency and reduce the loss of power management systems in a plethora of applications. 

Presenting Author: Aditi Bhattamishra Worcester Polytechnic Institute

Presenting Author Biography: Aditi Bhattamishra is a rising sophomore at Worcester Polytechnic Institute, with double majors in Robotics Engineering and Mechanical Engineering. She is interested in medical and space robotics, with a focus on actuator development and control, and power management and optimization.

Authors:

Aditi Bhattamishra Worcester Polytechnic Institute
Ya Tang Thayer School of Engineering, Dartmouth College
Yan Li Thayer School of Engineering, Dartmouth College