Bridging-Droplet Thermal Diode cooling Technology

    Recently, researchers from the School of Mechanical Engineering at Virginia Tech in the United States utilized the Vapor Chamber two-phase thermal conductivity principle to develop a planar Bridging Droplet Thermal Diode, which has a thermal conductivity effect 100 times that of the original. The Boreyko team hopes that the unidirectional heat transfer characteristics of the planar bridge droplet thermal diode will help achieve intelligent thermal management of electronic devices, aircraft, and spacecraft, and can serve as a new method for thermal management of data centers and space equipment.

    The Boreyko team created a thermal diode using two copper plates in a sealed environment, separated by a small gap. The first board adopts a wick structure to retain water, while the other board is coated with a waterproof (hydrophobic) layer. The water on the surface of the wick is heated and evaporates into steam. When steam passes through narrow gaps, it cools and condenses into water droplets on the hydrophobic side. When these water droplets become large enough to "close" the gaps, they are sucked back into the suction core, and the process begins again.

     In practical applications, the principle of fast unidirectional heat conduction of planar bridging droplet thermal diodes is the same as that of flat plate heat pipes (also known as Vapor Chambers), which can cover the heat source of electronic devices such as CPU chips, quickly remove heat, avoid heat accumulation on the chip exceeding the operating temperature limit, and ensure the safe operation of electronic devices.

     Heat is applied to the water absorbing plate opposite to the hydrophobic plate, and the steam condenses on the hydrophobic plate and jumps and agglomerates on the superhydrophobic surface. The water droplets cover the gaps and are sucked back by the liquid absorbing core plate, maintaining uninterrupted two-phase heat transfer. If the heat source is located on the hydrophobic side, this device will not generate steam because water is still trapped in the suction core. That's why this device can only conduct heat in one direction.