The heat preservation effect of the vacuum flask is mainly related to the manufacturing process of the product. The heat preservation effect of different processes is very different. The common vacuum flask is basically made of double-layer vacuum stainless steel and glass (the glass liner is mercury-plated and vacuum insulated). The production process and the insulation effect of the vacuum flask are beyond the scope of this article. The experience shared today is not to teach you how to choose a high-quality vacuum flask. This article only explains how to use it.
When you own a vacuum flask, its quality and capacity are a foregone conclusion. If you want to improve the thermal insulation effect of the vacuum flask, you can only start with the method of use and the details! First of all, we must understand a scientific concept: a good conductor of heat can speed up the heat loss of an object, and a poor conductor of heat can slow down the heat loss of an object. Stainless steel is an excellent conductor of heat, which absorbs heat quickly and dissipates heat quickly. Plastic, glass, ceramics and other materials are poor conductors of heat, and air is also a poor conductor of heat. When it comes to that, you may have to ask me why I use a vacuum flask. Is it made of stainless steel and needs to be vacuumed? The use of stainless steel is mainly determined by the characteristics of the material, such as safety, pressure resistance and other factors. It is precisely because the air is a poor conductor of heat that the excess air must be pumped away, so that the heat conduction is slower. Up! There are three ways of heat transfer: convection, conduction, and radiation, so even in a vacuum environment, heat can be transferred, but the speed slows down, for example, the heat from the sun is transferred to the earth. The vacuum of the thermos cup can only play the role of blocking the heat conduction as much as possible, but in fact, heat conduction will still occur. When the temperature of the water in the thermos cup is higher than the outside temperature, it can slow down the drop rate of the water temperature in the cup. When the temperature of the water in the thermos cup is lower than the outside temperature, the temperature of the water in the cup can be slowed down.
After understanding these principles, how can we use a vacuum flask to extend the heat preservation effect? First of all, when we install boiled water or ice water, we can put a little bit into it to preheat or pre-cool, then pour it out and then put the boiled water or ice water in (because the inner material will quickly absorb heat and reach a critical state) , But don’t fill up the entire tank, leave a part of the gap (air is a poor conductor of heat), so that the water and the lid cannot be contacted. Due to the slow thermal conductivity of air, the bottle stopper isolates the bottle mouth The water temperature drops slowly because of the remaining air, and a large amount of air is discharged from the bottle due to thermal expansion at the beginning. Then the temperature in the bottle decreases and the atmospheric pressure inside the bottle is lower than that outside the bottle, which is more conducive to heat preservation.
