The bottle has an inner wall and an outer wall; There is a vacuum between the two walls. Heat conduction and convection cannot be carried out in vacuum, but the metal-plated reflective layer can reflect thermal radiation. Therefore, any liquid poured into the bottle can keep its original temperature for a long time. This is why the thermos keeps warm in winter and cold in summer.

Extended data:

Principle of thermos bottle:

1, consisting of two layers of glass bottles, with vacuum in the middle, which isolates the heat conduction and convection of air;

2. Silver plating on the bottle wall, just like a mirror reflecting light, can reflect thermal radiation back into the bottle;

3. Cover the bottle stopper to prevent heat from leaking from the bottle.

Classification of thermos bottles

1, narrow mouth type. Also known as thermos. Small mouth diameter and good thermal insulation performance. Mainly used for holding boiled hot water, fried Chinese medicine juice, hot drinks and cold drinks.

2, big mouth type. Usually called an ice bottle, it has a large diameter and is convenient to take and put things. It mainly includes ice cubes, sorbets, cold drinks with containers, ice, liquefied gas, anti-fermentation substances and so on. You can also use containers for hot food and hot drinks.

3, cup type. Usually called a thermos cup, it has a large caliber and a small capacity. Tableware mainly used to reduce the influence of ambient temperature on contents in a short time.

Baidu encyclopedia-thermos bottle