When you have a thermos, its quality and capacity have become a foregone conclusion. To improve the insulation effect of the thermos, you can only start from the usage method and details! Firstly, we need to understand a scientific concept: a good conductor of heat can accelerate the dissipation of heat from an object, while a poor conductor of heat can slow down the dissipation of heat from an object. Stainless steel metal is an excellent conductor of heat, absorbing heat quickly and dissipating heat quickly. Materials such as plastic, glass, and ceramics are poor conductors of heat, and air is also poor conductors of heat. Speaking of which, perhaps you want to ask me why insulation cups are made of stainless steel and need to be vacuumed? The use of stainless steel materials is mainly determined by the characteristics of the material, such as safety, compression resistance, and other factors. It is precisely because air is a poor conductor of heat that excess air needs to be extracted, which slows down heat conduction! There are three ways of heat transfer: convection, conduction, and radiation, so even in a vacuum environment, heat can still be transferred, but the speed slows down, such as the heat from the sun transferring to the Earth. The vacuum effect of the insulated cup can only play a role in blocking heat conduction as much as possible, but in fact, heat conduction still occurs. When the temperature of the water in the insulated cup is higher than the external temperature, it can slow down the rate of water temperature drop in the cup. When the temperature of the water in the insulated cup is lower than the external temperature, it can slow down the rate of water temperature rise in the cup.

After understanding these principles, how can we extend the insulation effect when using insulated cups? Firstly, when filling with boiling water or ice water, we can preheat or pre cool a little bit first, then pour it out and then fill it with boiling water or ice water (because the inner layer material will quickly absorb heat and reach a critical state). However, do not fill the entire inner container, leave a gap (air is a poor conductor of heat), so that the water does not come into contact with the lid. Due to the slow thermal conductivity of the air, the bottle stopper isolates the convective heat transfer at the bottle mouth, and the water temperature drops slowly. Moreover, due to the presence of air, a large amount of air is initially discharged from the bottle due to thermal expansion. As the temperature inside the bottle decreases, the atmospheric pressure inside the bottle is lower than outside, which is more conducive to insulation.