Boiling water and other liquids is an energy-intensive part of many production processes, from power plants to cooling systems in electronics. Scientists at the Massachusetts Institute of Technology (MIT) have found a way to make it more efficient. The research was published in the journal Advanced Materials.
The boiling process is described by two key parameters: the heat transfer coefficient and the critical heat flow. Usually, in the design of materials, there is a compromise between them. Everything that improves one parameter worsens the other. A team of MIT researchers was able to significantly improve both parameters by combining different textures on the surface of the material.
Usually during boiling, many bubbles form on the surface under water. The more bubbles, the more efficient the boiling. However, if there are too many bubbles, they can merge into a film with steam on the surface and reduce its heat transfer.
To solve this problem, scientists covered the surface with a series of tiny tubes at a distance of 2 mm from each other. Bubbles were formed on the surface of the tubes, which made it possible to minimize their fusion.
However, this also resulted in fewer bubbles, which reduced boiling efficiency. Therefore, the researchers made even finer processing and covered the tubes with tiny sharp bumps. They increased the surface area and enhanced evaporation under the bubbles.
Finally, the tubes allowed moisture to reach the surface under the bubbles, which also improved the boiling process.
Tubes with holes of two sizes – 12 nm and 5 nm – participated in the research. In both cases, it was possible to significantly increase the heat transfer coefficient and the critical heat flow. Researchers have proven that such surface treatment can increase boiling efficiency. However, they emphasize that the work was done on a small scale in a laboratory setting. The structures they create are not designed to scale. Rather, they proved that such a system can work.
Next, scientists plan to look for alternative ways to create such structures that can be scaled to practical sizes.