Cooling off electronic circuits has been one of the main concerns of engineers for decades. Keeping those parts to an optimum temperature is vital, and there were many methods applied in this area, including liquid nitrogen, but they were either very expensive, or very hard to implement in a small scale environment.
Researchers from Purdue University discovered precisely how fluid boils in capilary cooling sytems, and that by designing a system by using those rules they got a much more efficient heat transfer between the object to be cooled and the liquid.
“One big question has always been, where is the transition from macroscale boiling to microscale boiling?” said doctoral student Tannaz Harirchian. “How do you define a microchannel versus a macrochannel, and at what point do we need to apply different models to design systems? Now we have an answer.”
The microchannels are etched directly on top of the silicon chips. Because both the channels and the chip are made of silicon, there is no dramatic difference in expansion from heating, which allows chips to be stacked on top of each other with the cooling channels between each chip. Unlike boiling liquid in larger cooling systems, spherical bubbles sometimes don’t form in the smallest channels. Rather, one long continuous “liquid annulus,” or oblong “slugs” of vapor in liquid form.
The new cooling system will be useful to hybrid and electric cars, where keeping temperatures low is a safety concern. For example, when you accelerate from 0 to 60 in less than 10 seconds, a large amount of power is transferred between the battery pack and the electrical coils, which causes them to get very hot. Regenerative braking would also use this kind of efficient cooling, allowing designers to improve their performance.