Carbon nanotube fabrics outperform metal heaters in gas heating, pointing toward industrial decarbonization

Published in Small. Rice University.

Industrial gas heating is one of the largest and most stubborn sources of carbon emissions. Factories worldwide burn fuel to heat gases for chemical production, drying, thermal treatment, and manufacturing. Electric heating sounds like an obvious fix, but the engineering constraints are severe: heaters immersed directly in gas streams must transfer energy rapidly and evenly while surviving extreme temperatures, mechanical stress, and destructive hot spots.

A cross-disciplinary team at Rice University has now demonstrated that heating elements made from carbon nanotube fibers (CNTFs) can consistently outperform conventional metal-alloy heaters on the metric that matters most: specific power loading, or the maximum heating power per unit mass before failure. The findings, published in Small, suggest that a material class more commonly associated with nanotechnology research could find practical application in heavy industry.

Thread-thin heaters that won't snap

The fundamental bottleneck in gas heating is size. Thinner heating elements exchange heat with flowing gases more effectively, but conventional metal alloys become fragile and difficult to fabricate at very small diameters. Carbon nanotube fibers sidestep this problem. They combine electrical resistivity suitable for Joule heating (generating heat by passing current through a resistor) with exceptional strength-to-weight ratios and high 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."

That flexibility is literal. You can tie a knot in a CNTF wire and it will not break. Try that with a nichrome heating element.

From single filaments to woven fabrics

Rather than retrofitting carbon nanotube fibers into existing heater designs, the team built devices from scratch using the fibers alone. They tested three configurations: single filaments, parallel arrays, and textile-like fabrics produced using weaving and knitting techniques. The fabric approach was particularly notable because it created lightweight, porous, three-dimensional structures with high surface area, exactly the geometry needed for immersion heating.

"Textile techniques give us extraordinary freedom in creating three-dimensional architectures," said Vanessa Sanchez, assistant professor of mechanical engineering. "We can design heaters that are lightweight, porous and mechanically compliant while remaining electrically functional."

Across all configurations and operating conditions, CNTF heaters achieved higher specific power loadings than comparable metal-alloy elements. The advantage was especially pronounced in non-oxidizing environments, where carbon-based materials can tolerate far higher temperatures without degrading.

Heat spreading changes the failure equation

One of the most common ways industrial heaters fail is through localized hot spots: small regions where temperature spikes, weakening the material until it breaks. The high thermal conductivity of carbon nanotube fibers helps distribute heat more evenly, suppressing these dangerous concentrations.

"Their high thermal conductivity helps distribute heat and suppress localized hot spots, which are a common cause of heater failure," said Geoff Wehmeyer, assistant professor of mechanical engineering. "That heat spreading fundamentally changes how these devices behave under extreme conditions."

Compared with rigid metal meshes, CNTF fabrics showed more uniform heating behavior, a result the team attributes directly to the fibers' ability to conduct heat along their length.

Scaling from lab to factory floor

The study is a materials demonstration, not a commercial product launch. Several practical questions remain before carbon nanotube fiber heaters could see industrial deployment. Long-term durability under continuous operation, behavior in oxidizing atmospheres at the highest temperatures, and cost at production scale are all open issues. The research benefited from collaboration with industrial researchers at Shell and with DexMat, a company that has commercialized CNTF production, suggesting the manufacturing pathway is not purely theoretical.

"Electrifying industrial heat is one of the most important, and most difficult, pieces of decarbonization," said first author Monisha Vijay Kumar, a graduate student in applied physics. "We wanted to understand whether an entirely different class of materials could expand what's possible in gas heating."

The answer, at least in lab conditions, appears to be yes. Whether that translates to factory conditions at competitive cost is the next question.