When you have a thermos mug, its quality and capacity are a foregone conclusion. If you want to improve the insulation effect of the thermos mug, 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 might ask me why I use a vacuum flask. Is it made of stainless steel and needs to be vacuumed? The use of stainless steel materials 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. NS! There are three ways of heat transfer: convection, conduction, and radiation. Therefore, even in a vacuum environment, heat can be transferred, but the speed is slowed down, such as the transfer of heat from the sun to the earth. The vacuum of the thermos cup can only play the role of blocking the heat insulation 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 rate of increase of the water temperature 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 fill it with boiled water or ice water (because the inner material will quickly absorb heat and reach a critical state) , But don’t fill up the entire inner 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 the air, the bottle stopper isolates the bottle from the mouth. The temperature of the water drops slowly because of the remaining air. At the beginning, a large amount of air is discharged from the bottle due to thermal expansion. Then the temperature in the bottle decreases and the atmospheric pressure inside the bottle is lower than the outside of the bottle, which is more conducive to heat preservation.