MIT (Massachusetts Institute of Technology) is an American university founded in 1861. It is one of the best technological institutes in the world. Youngsup Songa recent graduate of the facility, with the help of several other researchers, discovered a new, faster and more economical way to boil water. In a recent article in the journal Advanced Materials, the team explains that to arrive at the boiling phase, it is necessary that two indicators are present: the heat transfer coefficient (CHF) and the heat flow. However, the optimization of these two parameters is difficult because they are interdependent. Thereby, improving one will weaken the other. Anyway, MIT scientists claim to have succeeded in developing a solution to improve both factors at the same time.
The boiling theory
In the post, Song claims to have managed to find a solution to mitigate the effect of the presence of a vapor film that makes the boiling process less efficient. “The more bubbles on the boiling surface, the more efficient the boiling. But when there are too many bubbles, they tend to merge. This fusion phase generates the creation of a layer of vapor above the boiling surface. The presence of this film of vapor located between the hot surface and the water then hinders the efficiency of heat transfer and the CHF value”, he explained. Research then focused on surface modifications at several size scales.
A new method of surface treatment
First, the researchers added to a surface a series of cavities 10 µm wide separated by about 2 mm from each other. This group of micro-cavities has the role of controlling the formation of bubbles and to keep them fixed, thus blocking the formation of the vapor film. Unfortunately, when the number of bubbles on the surface is reduced, it decreases the efficiency of the boiling process. To circumvent this problem, the team developed a surface treatment technique on an even smaller scale. It consists of add tiny bumps and ridges to speed up evaporation.
Laboratory observations
To form the cavities, Song and his collaborators had to install a series of columns on the surface of the material. Associated with nanostructures, these columns allow the evacuation of water from bottom to top, which accelerates the boiling phase. In conclusion, the young MIT graduate explains that: “Combining the three levels of surface modification which are cavity separation, columns and nanoscale texturing greatly optimizes the efficiency of the boiling process. » According Evelyn Wang, professor at MIT, the experiments they conducted were limited to laboratory observations. This discovery could, however, contribute to the improvement of electronic temperature management systems. But before this becomes possible, further research will still be needed.
