A thermal management material that responds to heat or cold by folding or unfolding without need for a power source

Bob Yirka is a research scientist at Phys.org.

A thermal management multi-layer material that responds to heat or cold without an external power source has been developed by a team of researchers. The group describes in their paper how they developed the material and how it performed when tested.

Solar power and radiative cooling technologies are examples of ways to use those that have already been developed. The researchers wanted to shift a device between using solar heating or radiative cooling without the need for a secondary power source.

The Himalayan rabbit, which has fur that changes color depending on the season, and the leaves of the pudica plant inspired the researchers. It was suggested that a material similar to the plant could be made that could be used to switch between thermal devices.

The researchers came up with a multi-layer material that behaved as they had imagined. The material was made from a single piece of plastic. Material was used to make each of the subunits.

The finished product was made using an automatic actuator with a cooling effect on the surface. The material would be laid flat until the temperature reached a certain point. The top layer would roll into a tube and expose the dark material below.

Under different temperature conditions, the researchers laid the material down. The solar heating capability was 252.2 watt per square meter. The cooling power was around 59.7 watt per square meter. The material could be used in real-world settings as a thermal management device that requires zero energy to operate.

More information: Quan Zhang et al, Bioinspired zero-energy thermal-management device based on visible and infrared thermochromism for all-season energy saving, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2207353119 Journal information: Proceedings of the National Academy of Sciences

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