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Three ways of heat transfer: heat radiation, heat convection, and heat conduction. We feel warm when the sun shines because the heat radiating from the sun hits us, which is called heat radiation. To prevent heat radiation we have to block it back, and one of the best materials to send the heat rays is mirror.
After you pour a cup of boiled water on the table, the temperature of the water will gradually cools down to that of the surrounding environment, because the flow of water in the cup and the surrounding air. The foregoing phenomenon is hot convection. You can block the channel for convection by putting a lid at the top of the cup. Nevertheless, the glass of water will still cool down, a little slower though. This is because the cup itself has the property of heat transfer, which is called heat conduction. Inquiry vacuum flask pump dispenser.
The liner of the glass lined vacuum flask is made of double-layer glass which is plated with silver. The mirror-like surface enable it to reflect the heat rays back. In this way, the channel of heat radiation is blocked off. By vacuuming between the two layers of glass vacuum thermos flask jug, the prerequisite of convection conduction is unrealized.
We choose cork to shout the glass mouth as it is not easy to transfer heat, which means the channel of heat conduction is blocked. If we can fully block the three paths of heat conduction, the heat can be retained for good. However, the small-calibre liner's property of heat protection is not that ideal, and a part of heat can still come out, for which vacuum flask can only retain the temperature for a certain while.
The function of the airpot vacuum flask is to maintain the temperature of the hot water in the bottle by cutting off the heat exchange between inside and outside of the bottle. Therefore, the inside "hot air" cannot get out while the "cold air" outside can't get in. In that case, if you put ice cream in the vacuum flask, it will not melt as the "heat" outside is not easy to come into the bottle. Actually, it is reasonable to call the personalised thermos flask temperature-protector for it can keep both "warmth" and "coldness".
The vacuum flask used at home can keep the temperature of hot water very well. What are the scientific principles behind it? That the hot water turns cold is caused by convection, conduction and radiation of heat. The glass liner is invented based on the above three phenomena.
First, a cork is used on the mouth of the vacuum flask to prevent heat convection. Second, the gap between the double-layer vessel is vacuumed to address the heat conduction. Third, a thin layer of silver is painted on the liner, creating a mirror-like surface to reflect heat and lights, and thereby the heat radiation can be sent back. In this way, the heat will not disperse and and the temperature can be maintained.
