Research has shown that adding a small amount of hydrofluoroether to conventional water-based turbulent heat transfer systems improves their ability to transfer heat by 500%..
Turbulent heat exchangers are fairly simple devices that use the natural movement of fluid to move heat. As a result of the change in density, water begins to circulate from a hot area to a cold area through the connecting tank. This type of heat exchange is the basis of modern heating, ventilation and air conditioning systems..
Researchers from Tsinghua and Brown Universities have studied hydrofluoroether (HFE), which is sometimes used to speed up heating cycles, as the only liquid in heat exchangers. However, they suggested that using it as a supplement could further boost the intensity. Experimentally, scientists have found that HFE concentration of about 1% maximizes heat transfer and leads to an increase in heat flux up to 500%.
Using laser diagnostics and high-speed imaging methods, it was found that being near the hot side, the hydrofluoroether globules quickly boil and rise to the cold area, forming two-phase bubbles of vapor and liquid. There they lose heat and sink in liquid form..
According to researchers, bubbles affect the overall heat flow in two ways. In addition to removing significant amounts of heat from the hot area, they also increase the rate of rise and fall of surrounding water plumes..
The team claims the HFE7000 additive they use is non-flammable and does not cause corrosion or ozone formation. The limitation is that this method is only suitable for vertical heat transfer systems. but scientists are already developing ways to adapt for parallel systems.
We also previously reported on the development of an industrial thermoacoustic energy converter that uses excess heat to cool air or water without additional power supplies..
text: Ilya Bauer, photo: tm24, video: YouTube / Brown University
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