Researchers Develop Nanorods for Better Nano-Scale Heat Transfer

Researchers at Rensselaer Polytechnic Institute have discovered a new method for growing single-crystal nanorods and controlling their shape using biomolecules which could enable more efficient heat transfer methods. These new methods could be useful in the development of more powerful and efficient nano-scale heat pumps and devices that harvest electricity from heat.

The researchers were also able to create structures that branched off in different directions by carefully controlling the temperature, time, and amount of biomolecular surfactant used during synthesis of the nanorods. The two-material nanorods consist of a single-crystal bismuth telluride core encased in a shell of single-crystal bismuth sulfide. These "core-shell" nanorods have attractive physical properties and are expected to one day enable the development of new nanoscale thermoelectric devices for power generation, as well as nanoscale heat pumps for cooling hot spots in nanoelectronics devices.

RPI Team Discovers More Efficient Way to Boil Water

Researchers at Rensselaer Polytechnic Institute made one of those great, accidental discoveries that I really love recently. The added an invisible layer of copper nanorods to the bottom of a metal pot and discovered that it took an order of magnitude less energy to boil water in the vessel. The increase in heat transfer efficiency could have applications in a number of areas, including the cooling of computer chips and reduced costs for operating industrial boilers.

Project leader Nikhil A. Koratkar believes that the efficiency gain happens because tiny "nanobubbles" form within the nanoscale cavities amongst the nanotubes and feed into the microscale cavities of the vessel's surface, preventing them from getting flooded with water. This coupling effect promotes robust boiling and stable bubble nucleation, with large numbers of tiny, frequently-occurring bubbles.

Boiling is ultimately a vehicle for heat transfer, in that it moves energy from a heat source to the bottom of a vessel and into the contained liquid, which then boils, and turns into vapor that eventually releases the heat into the atmosphere. This new discovery allows this process to become significantly more efficient, which could translate into considerable efficiency gains and cost savings if incorporated into a wide range of industrial equipment that relies on boiling to create heat or steam.

“If you can boil water using 30 times less energy, that’s 30 times less energy you have to pay for,” Koratkar said.

The team’s discovery could also revolutionize the process of cooling computer chips. As the physical size of chips has shrunk significantly over the past two decades, it has become increasingly critical to develop ways to cool hot spots and transfer lingering heat away from the chip. This challenge has grown more prevalent in recent years, and threatens to bottleneck the semiconductor industry’s ability to develop smaller and more powerful chips.