EPFL Researchers Demonstrate Heat Flow Toward Warmer Regions
EPFL researchers have theoretically demonstrated that heat can flow toward warmer regions in highly ordered materials without violating the laws of thermodynamics. This groundbreaking research could significantly contribute to the design of electronics with minimized heat loss.
Understanding Heat Flow and Phonon Hydrodynamics
Heat typically flows toward cooler regions, a principle described by the second law of thermodynamics. In materials, thermal energy causes atoms to vibrate, which are quantum mechanically described as phonons, quasiparticles that transport heat. While phonon collisions usually cause slow heat dissipation, in highly ordered, pure crystals, these collisions can result in a fluid-like, directional heat flow known as phonon hydrodynamics.
EPFL's Breakthrough: Harnessing Heat Backflow
Researchers from the Theory and Simulation of Materials group at EPFL, led by Nicola Marzari, utilized simulations to show that hydrodynamic heat flow can generate heat vortices and enable heat to move from cooler to warmer areas. Their analytical model illustrates how to maximize this hydrodynamic heat flow in a 2D strip of crystalline graphite, providing a tool for utilizing heat 'backflow' in thermal energy management for electronic devices.
Enrico Di Lucente, a former EPFL researcher and first author, explained that their analytical framework indicates heat backflow is maximized when the flow is nearly incompressible. This incompressible flow redirects heat backward when encountering resistance, which can lead to more efficient, coordinated flow by reducing heat buildup.
Impact Across Industries
Published in Physical Review Letters, this work is expected to impact heat management in various sectors, including consumer electronics, industry, energy storage, data centers, and cloud computing. The researchers suggest that a hydrodynamic component could direct thermal energy away from heat-sensitive parts like smartphone batteries. Marzari emphasized that the formulations could be applied to study other microscopic carriers.