What are the advantages and disadvantages of long-term use of thermos cups?

Modern thermos was invented by British physicist Sir James Dewa in 1892. At that time, he was engaged in a research project on liquefied gas. In order to liquefy the gas at low temperature, he first needs to design a container that can isolate the gas from the outside temperature, so he asks the glass technician Berg to blow a double-layer glass container for him, coat the inner walls of the two layers with mercury, and then vacuum the air between the two layers. This kind of thermos, also called "Dupin", can keep the liquid in it unchanged for a certain period of time whether the temperature is cold or hot.

Because thermos bottles are mainly used to keep warm hot water at home, they are also called thermos bottles. The structure of thermos bottle is not complicated.

There is a double glass bottle liner in the middle. These two layers are evacuated and plated with silver or aluminum. The vacuum state can avoid thermal convection. Glass itself is a poor conductor of heat, and silver-plated glass can reflect the heat energy radiated from the container. On the contrary, if the cold liquid is stored in the bottle, the bottle can prevent the external heat energy from radiating into the bottle.

The cork of thermos bottle is usually cork or plastic, both of which are not easy to conduct heat. The shell of thermos bottle is made of bamboo, plastic, iron sheet, aluminum, stainless steel and other materials. There is a rubber cushion at the mouth of the bottle and a bowl-shaped rubber cushion seat at the bottom of the bottle to fix the glass liner and prevent it from colliding with the shell.

But don't use stainless steel thermos cups to make tea, which is harmful to human body.

Why is it easy to lose vitamins when making tea in stainless steel thermos cups? Usually tea contains a variety of vitamins, in addition to a large number of theophylline, tea sesame oil, tannic acid. Soaking tea in stainless steel thermos cup in high-temperature water for a long time will lead to the destruction of many vitamins in tea, a large amount of tannic acid and theophylline oozing out at the same time, and a large amount of tea sesame oil evaporating. In this way, many ingredients in many tea leaves are lost, and the nutritional value of tea leaves is reduced, which will make the tea juice tasteless.

Therefore, in our daily life, we'd better not use stainless steel thermos cups to make tea. If you want to drink tea, it's also convenient. We can soak the tea in a teapot or tea set first, and then pour it into a stainless steel thermos cup, so that the vitamins will not be lost and the tea can be kept warm.