How does the thermos bottle keep warm?

When people are close to the fire source, they will feel warm. This is the heat from the fire source being transferred to the person's body. This is heat radiation. The best way to prevent the heat radiation from losing is to reflect it back with a mirror.

Where a cup of boiling water is placed, the heat emitted by the boiling water and the convection of the air will slowly absorb the heat, and the boiling water will become cooler. If you add a lid to the cup, the heat will not convection with the air, which will slow down the cooling time of the boiling water. .

The thermos bottle is made of double glass. The glass wall is coated with a layer of silver like a mirror, which can reflect the heat flowing in the bottle back. The air is drawn between the double glass to form a vacuum. Air is the medium for heat transfer. The vacuum layer This increases the difficulty of heat dissipation. Adding a cork to the bottle mouth cuts off the final path of heat dissipation, but the water bottle can’t be kept warm, which can only slow the heat dissipation time.

The thermos bottle can not only keep heat, but also keep cold things at lower temperature. When a popsicle is put in, it can also isolate the hot air from outside from entering the bottle, and the hot and cold air cannot be convective to achieve the effect of keeping cold.