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Introduction to vacuum flask


Thermos kettle: The kettle, also known as a vacuum flask or a thermos, was invented by the English scientist Dewar. In 1900, he for the first time turned compressed hydrogen into a liquid, liquefied hydrogen. This kind of thing had to be packed in a bottle, but there was no such thermos flaskvacuum flask at that time. He developed it himself. He used a vacuum method, that is, making a double-layered bottle, sucking out the air in the compartment and cutting off the conduction.

The modern vacuum flask was invented by British physicist Sir James Dewar in 1892. At that time, he was conducting research work on liquefying gas. To liquefy gas at low temperatures, he first needed to design a container that could isolate the gas from the outside temperature. So he asked glass technician Berg to blow a double-sided container for him. Layer a glass container, coat the inner walls of the two layers with mercury, and then remove the air between the two layers to create a vacuum. This kind of vacuum flask is also called a "Du bottle", which can keep the temperature of the liquid inside it unchanged for a certain period of time regardless of whether it is hot or cold.

Since thermos bottles are mainly used to keep hot water warm in the home, they are also called thermos bottles. The structure of the thermos flask is not complicated. There is a double-layer glass bottle in the middle. The two layers are evacuated and plated with silver or aluminum. The vacuum state can avoid heat convection. The glass itself is a poor conductor of heat. The silver-plated glass can radiate the inside of the container outwards. The heat energy is reflected back. In turn, if a cold liquid is stored in the bottle, the bottle prevents heat energy from outside from radiating into the bottle. The stopper of a thermos bottle is usually made of cork or plastic, both of which are not easy to conduct heat. The shell of the thermos bottle is made of bamboo, plastic, iron, aluminum, stainless steel and other materials. The mouth of the thermos bottle has a rubber gasket and the bottom of the bottle has a bowl-shaped rubber seat. These are used to fix the glass bladder to prevent collision with the shell. .

The worst place for a thermos bottle to keep heat and cold is around the bottleneck, where most of the heat circulates through conduction. Therefore, the bottleneck is always shortened as much as possible during manufacturing. The larger the capacity and the smaller the mouth of the thermos bottle, the better the insulation effect. Under normal circumstances, the cold drink in the bottle can be kept at 4 in 12 hours. About C. Boiling water is around 60℃.

Vacuum flask s are closely related to people's work and life. It is used to store chemicals in laboratories, people use it to store food and drinks during picnics and football games, contact thermos bottles, etc. But the principle of thermal insulation remains unchanged.