The near-vacuum between the inner and outer flasks helps to further prevent heat loss by convection. Starting from the top, that tight-fitting lid seals off the chamber and prevents heat transfer by both convection and evaporation. Why are vacuum-seal flasks so effective at heat retention? That depends on how you look at it, as there are four major ways to describe heat loss - convection, conduction, radiation, and evaporation. Highways for Heat The four major methods of heat transfer. And they’re still used to keep liquefied gases liquid. Vacuum-seal flasks are also used in MRI machines to keep the superconducting magnet cool. They are widely used throughout the industrial, scientific, and medical fields for everything from preserving bodily fluids and tissue to measuring electric power, recording the weather, and detecting an airplane’s rate of climb. These vessels have a ton of uses other than keeping your coffee hot or your tea iced. Heat cannot travel through a vacuum, so the contents stay at-temperature for much longer than they would outside the flask. Sir Dewar’s flask consisted of two flasks separated by a near-vacuum that does much of the job of heat retention. Six years later, he would be the first person to liquefy hydrogen and is considered a founding father of cryogenics.Īt the time, liquefying gases was an expensive process, and it was important to keep them in a fluid state as long as possible. It was first invented by Scottish chemist Sir James Dewar and presented to the Royal Institute in 1892. The vacuum-seal flask is surprisingly old technology. Of course this got me to wondering how exactly vacuum-seal flasks, better known in household circles as Thermoses work, and how they were invented. Sir James Dewar’s original vacuum-seal flask. Besides looking totally awesome on my side desk, this thing still works like new, at least as far as I can tell - it’s older than I am. I recently started using a 50-year-old vacuum-seal flask that belonged to my Grandpa so that I don’t have to leave the dungeon as often to procure more caffeine.
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