A team of researchers from Shanghai Jiao Tong University China recently explored the possibility of keeping electronics cool through the imitation of the sweating mechanism of mammals. They recently published their study in a well-established journal, Joule, stating that a coating on electronics releases water vapor, which gets rid of the heat generated by running devices. It is a new type of thermal management that has the ability to reduce overheating in electronics while keeping the temperatures under control.
Devices, such as computers, typically use fans for temperature regulation. But fans are power-consuming, noisy, and bulky. And they are unsuitable for smaller devices like mobile handsets. Makers of such devices use Phase Change Materials (PCMS) such as fatty acids or waxes to cool down the phones.
These materials can absorb heat produced by devices when they melt. However, the total amount of energy exchanged during the solid-liquid transition is relatively low. In contrast, the liquid-vapor transition of water can exchange 10 times the energy compared to that of PCM solid-liquid transition.
“The development of micro-electronics puts great demands on efficient thermal management techniques because all the components are tightly packed and chips can get really hot,” said senior author Ruzhu Wang, who studies refrigeration engineering at Shanghai Jiao Tong University. “For example, without an effective cooling system, our phones could have a system breakdown and burn our hands if we run them for a long time or load a big application,”
Inspired by mammals’ sweating mechanism, the researchers studied a group of porous materials that could absorb moisture from the air and release water vapor when heated. Out of the materials studied, metal organic frameworks (MOFs) were the most promising because they could store a large amount of water and, therefore, take away more heat when heated.
“Previously, researchers have tried to use MOFs to extract water from the desert air,” added Wang. “But MOFs are still really expensive, so large-scale application isn’t really practical. Out study shows electronics cooling is a good real-life application of MOFs. We used less than 0.3 grams of material in our experiment, and the cooling effect it produced was significant.”
The type of MOF selected by Wang’s team is known as MIL-101 (Cr) for this specific purpose. Its water-absorbing capacity along with better sensitivity to temperature fluctuations make it ideal for such purposes. The researchers coated the pieces with 16 cm 2 aluminum sheets with MIL- 101 (Cr) of varying thicknesses — 516, 313, and 198 micrometres. These sheets were heated over a hot plate.
It was discovered that MIL-101Cr coating delayed temperature rise in the sheets. As the thickness of the coating increased the temperature rise delayed more and more.
“In addition to effective cooling, MIL-101 (Cr) can quickly recover by absorbing moisture again once the heat source is removed, just like how mammals rehydrate and ready to sweat again,” he said. “So, this method is really suitable for devices that aren’t running all the time, like, phones, charging batteries and telecommunications base stations, which can get overloaded sometimes.”
To see the effect of MIL-101 (Cr) on real-life devices, the team applied the coating on a microcomputing device. It was observed that this new coating kept the temperature down to 7 C even when the device ran on its heavy workloads for 15 minutes constantly. In future, the team further plans to improve the thermal conductivity of this material by incorporating better thermal conductive additives like graphene.