ORNL, UMaine researchers harness “mini tornado” tech to improve cellulose nanofiber production

Model of tornado-like spinning air within the high shear drying system. Sources | ORNL, U.S. Dept. of Energy

Scientists from the U.S. Department of Energy’s (DOE) Oak Ridge National Laboratory (ORNL, Tenn., U.S.) and the University of Maine (UMaine, Orono, U.S.) have developed a high-shear drying technique that could transform how cellulose nanofibers are produced for sustainable materials applications. The novel method uses counter-rotating vortices of heated compressed air — likened to tiny tornadoes — to dry cellulose nanofibers more efficiently and at a larger scale than conventional approaches.

Cellulose nanofibers are plant-based materials with high strength and versatility, with potential uses ranging from stronger concrete and biodegradable packaging to medical implants. However, drying these nanofibers from water-rich slurries without causing them to clump together has been a persistent challenge for manufacturers. Traditional freeze-drying is energy-intensive and suited for small batches, while spray-drying can yield aggregated fibers that reduce material quality.

This latest approach, developed through a collaboration between ORNL researchers and UMaine chemical engineering professor David J. Neivandt and his team, leverages high-speed heated air vortices that impart intense shear on cellulose slurry droplets. This shear prevents fiber aggregation, enabling rapid dehydration with reduced energy consumption and improved yield and quality of nanofibers.

The research address the growing demand for cellulose nanofiber across multiple industries seeking low-cost, low energy-intensive and natural materials. These industries include packaging, building and construction, marine and automotive.

“Cellulose nanofibers are like branches on a tree,” says Peter Wang, a research staff scientist in ORNL’s Manufacturing Science Division. “You have a trunk that’s smaller than the diameter of a hair, but then the ends continue to split until you have fuzzy ends that are nano-size.”

Computational modeling by ORNL’s Kevin Doetsch revealed that air enters the vortex generators at speeds reaching Mach 3, helping to tear apart slurry droplets and dry them effectively. This insight was enabled by advanced simulations on high-performance computing systems. Future work will focus on scaling the process to higher throughput to meet industry demand.

The research is part of the SM2ART Program, supported by the DOE’s Advanced Materials and Manufacturing Technologies Office to help scale natural, low-energy materials production across diverse industrial sectors.

For a more in-depth read, find the complete announcement on the ORNL website.