Steam from power plants is turned back to water using condensers. They have are essential, not only for most power generation systems, but also for the world’s supply of fresh water. A surface architecture, designed by a team of scientists at MIT, might increase the performance of these so-important instruments.
According to a study just released in ACS Nano, the key is to combine microscopic patterning. This is essentially a surface covered with small bumps and coated with lubricant such as oil, which is held between the spaces through a capillary action.
The team, led by Sushant Anand, a postdoc at MIT, measured the speed of movement of droplets condensed on this surface. The faster the speed, the more droplets are formed and therefore the higher the efficiency of heat transfer in a powerplant condenser.
The authors claim that the newly developed architecture requires a minimal quantity of lubricant with very low vapor pressure. If lost, it can be easily replaced from a fitted reservoir at the edge of the surface. The lubricant also acts as a protecting coat against corrosion. Furthermore, the only requirement is that the dimensions of the textures are the same, making the manufacturing process very simple.
Kripa Varanasi, the Doherty Associate Professor of Ocean Utilization, is planning to take their research further. Ideally, they would like to be able to estimate how much exactly they can improve the performance of condensers in powerplants. She is convinced that saving as little as 1 percent could already have a very significant impact on reducing greenhouse gas emissions.
Varanasi is working on a parallel study with a different team at MIT. The aim is to improve the technique by obtaining direct, detailed images of the interface between a liquid and a surface. In order to study the interface that is normally hidden by the droplets, they do not rely on computer modeling as everyone else. The new method uses techniques to freeze the droplets on the surface. These are then sliced in cross-sections with an ion beam.
The freezing process using liquid nitrogen helps preserving the geometry of the samples. The freezing rate is fast, which prevents the liquid from crystalizing. According to Varanasi, the technique is completely new and reveals details about the surfaces that have not been seen before.