A team of researchers from the Nanyang Technological University (NTU) in Singapore has developed a thermal invisibility cloak that would improve heat distribution in electronic devices by redirecting incoming heat. The cloaks are capable of guiding heat around a hidden object, thus resulting in complete thermal invisibility.
“Based on carefully engineered metamaterials – materials with properties that can’t be found in nature – the technology could potentially help improve the thermal performance of various electronic systems by fine-tuning thermal dissipation,” according to Engineering and Technology Magazine.
The cloak is made of 24 small thermoelectric semiconductor heat pumps, which are controlled by external input voltages. The heat-pumps distribute heat around a 62-millimeter air hole in a carbon steel plate, which is only 5mm thick.
The research team recently invented an on/off switch for the cloak.
“We considered the question of whether we can control thermal cloaking electrically, not by guiding heat around the hidden object passively with traditional metamaterials, but by ‘pumping’ heat from one side of the hidden object to the other side actively, with thermoelectric modules,” Professor Baile Zhang, lead researcher in the project, noted.
“The device could help optimize the thermal performance of a large variety of electronic devices including high-power engines, magnetic resonance imaging instruments and thermal sensors. Because of its shape flexibility, the active thermal cloak might also be applied in human garments for effective cooling and warming, which makes a lot of sense in tropical areas such as Singapore,” Zhang added.
“In the experiments, the researchers attached the modules to two surfaces with temperatures of 60°C and 0°C. Subsequently, they applied a variety of specific voltages to each of the 24 modules and observed how the heat falling on the hot-surface side of the air hole was absorbed and delivered to a constant-temperature copper heat reservoir attached to the modules. The modules on the cold-surface side released the same amount of heat from the reservoir into the steel plate. This prevented heat from diffusing through the air hole,” Engineering and Technology Magazine reported.
“Additionally, the researchers found that their active thermal cloaking was not limited by the shape of the object being hidden. When applied to a rectangular air hole, the thermoelectric devices redistributed heat just as effectively as in the circular one.”
Zhang and his team plan to apply thermal cloaks in electronic systems in the near future, which could improve the efficiency of heat transfer in electronics.
The team’s work is described in an article in the latest issue of Applied Physics Letters.
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