In research backed by the National Science Foundation, the U.S. Department of Energy, Shell, The Carbon Hub, and others, a team at Rice University’s Smalley-Curl Institute demonstrated that wires and fabrics made from carbon nanotube fibers (CNTFs) can produce significantly greater heating power per unit mass than conventional metal-alloy heaters when exposed directly to flowing gases.
Industrial processes—from chemical production and drying to thermal treatment—commonly rely on fuel combustion to heat gases. While electric heating offers an alternative, warming moving gases is technically demanding as heaters must deliver rapid, uniform heat transfer without creating hot spots or failing under extreme temperatures. Immersion heating, where elements are placed directly in the gas stream, can boost efficiency but also expose materials to greater thermal and mechanical stress.
Thinner elements transfer heat more efficiently, but conventional metal alloys are difficult to produce and manage at small diameters. Carbon nanotube fibers (CNTFs) offer suitable electrical resistivity for Joule heating along with high strength-to-weight ratios and superior thermal conductivity.
“Carbon nanotube fibers behave very differently from metal wires,” said Matteo Pasquali, the A.J. Hartsook Professor of Chemical and Biomolecular Engineering and director of the Carbon Hub. “They are lightweight, flexible and remarkably strong, which allows us to consider heater geometries and fabrication techniques that would be impractical with conventional materials.”
Instead of fitting CNTFs into conventional designs, the team created heaters made entirely from the fibers, ranging from single filaments to arrays and fabric-like structures. Performance was evaluated using specific power loading, or the maximum heating power per unit mass before failure. CNTF heaters outperformed comparable metal-alloy elements, especially in nonoxidizing environments where carbon materials can tolerate higher temperatures. Their superior thermal properties also played a key role in enhancing heat transfer.
Vanessa Sanchez, assistant professor of mechanical engineering, contributed expertise in advanced manufacturing and textile technologies that helped translate nanoscale fibers into device-scale systems.
“Textile techniques give us extraordinary freedom in creating three-dimensional architectures,” Vanessa Sanchez, assistant professor of mechanical engineering, said. “We can design heaters that are lightweight, porous and mechanically compliant while remaining electrically functional.” The results highlight a promising new approach to electrifying industrial heating—an essential yet complex step in reducing carbon emissions.
