How long can the thermos be kept warm?

A thermos can keep the temperature of the water in the bottle for a long time. At present, many people in our country use thermos bottles to keep warm. However, in the process of using thermos, the time of heat preservation often has a great influence on people's daily life. So how long can the thermos be kept warm?

How long can a thermos bottle keep warm? After 24 hours, the temperature of the thermos bottle shall not be lower than 60℃. When the thermos bottle is filled with boiling water, don't fill it too full. There is a certain gap between the water and the cork to prolong the heat preservation time.

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 pad at the mouth of the bottle and a bowl-shaped rubber pad at the bottom of the bottle to fix the glass liner and prevent it from colliding with the shell.

The worst function of thermos bottle is around the bottleneck, where the heat is mostly circulated by conduction. So when manufacturing, always try to shorten the bottleneck. The larger the capacity, the smaller the bottle mouth, and the better the insulation effect. In general, the cold drink in the bottle can be kept at about 4℃ within 12 hours. Boiling water is about 60℃.

The inner container structure of thermos bottle is closely related to people's work and life. It is used to store chemicals in the laboratory, and people use it to store food and drinks at picnics and football matches. In recent years, many new designs have been added to the outlet of hot water bottles, such as pressure hot water bottles and contact hot water bottles. But the principle of heat preservation remains unchanged.

It consists of two glass bottles inside and outside. They are connected into a whole at the bottle mouth, the gap between the two bottle walls is vacuumed to weaken thermal convection, and the surface of the glass bottle wall is plated with bright silver film to reflect infrared radiation. When the temperature in the bottle is high, the heat energy of the contents does not radiate outward. When the temperature in the bottle is low, the heat energy outside the bottle will not radiate into the bottle, and the thermos bottle effectively controls three heat transfer modes: conduction, thermal convection and radiation.

The weak point of thermos insulation is the bottle mouth. There is heat conduction at the joint of inner and outer glass bottles, and the bottle mouth is usually blocked with cork or plastic plug. Therefore, the larger the capacity of the thermos bottle, the smaller the bottle mouth and the higher the heat preservation efficiency. It is very important to maintain the high vacuum of bottle wall interlayer for a long time. If the interlayer expands gradually or the seal exhaust tail is damaged, the vacuum state of the interlayer is destroyed, and the insulation effect of the thermos bottle liner will be lost.

In addition to glass, thermos bottles are made of stainless steel or non-toxic and tasteless plastic. Metal bottle liner is durable and not easy to be damaged, but its thermal conductivity is much higher than that of glass, and its thermal insulation efficiency is slightly poor.