The thermos is also called heat: the kettle and the thermos are heat preservation appliances invented by the English scientist Dewar. The thermos has an inner wall and an outer wall, and the two walls are in a vacuum. The reflective layer can reflect thermal radiation.
Therefore, any liquid poured into the bottle can maintain its original temperature for a long period of time. That's why thermoses keep hot drinks in winter and cold drinks in summer.
The structure of the vacuum flask is a double-layer glass liner in the middle, which is vacuumized between the two layers and plated with silver or aluminum. Now it is mostly magnesium oxide. The vacuum state can avoid heat convection. The glass itself is a poor conductor of heat. The silver glass can reflect the heat energy radiated from the inside of the container back. Conversely, if a cold liquid is stored in the thermos, this bottle can prevent the outside heat from radiating into the bottle.
Thermos stoppers are usually made of cork or plastic, neither of which conduct heat well. The shell of the vacuum flask is made of bamboo, plastic, iron sheet, aluminum, stainless steel and other materials. There is a rubber gasket at the mouth of the vacuum flask and a bowl-shaped rubber seat at the bottom of the bottle. These are used to fix the glass liner to prevent collision with the shell.
There are many types of vacuum flasks, which can be divided into the following three types according to different forms:
1. Thin mouth
Usually also known as a vacuum flask. The diameter of the mouth is small, and the thermal insulation performance is good. It is mainly used to hold boiling hot water, decocting hot Chinese medicinal juice, hot drinks and cold drinks, etc.
2. Wide mouth type
Usually also known as an ice bottle, the diameter of the mouth is large, and the items are easy to pick and place. Mainly hold ice cubes, sorbet, cold drinks with containers, iced medicine, liquid gas, anti-fermentation substances, etc., suitable for holding hot food, hot drinks with containers, etc.
3. Cup shape
Usually also known as a thermos cup, the diameter of the mouth is large and the capacity is small. It is mainly used as a eating utensil to reduce the influence of the ambient temperature on the contents in a short time.
When purchasing an insulated hot water bottle, you should pay attention to choosing a product with a suitable size and function according to your needs and budget, and purchase through regular channels. When purchasing, pay attention to check the following details:
1. Look at the shell
The shell of the vacuum flask generally has several kinds of metal, plastic, and stainless steel. The metal casing is relatively hard and not easy to break, but it is prone to rust when exposed to water frequently. The plastic shell is more beautiful and has a variety of styles, but it is easy to break after a long time. The stainless steel shell is not easy to rust and the quality is better.
2. Look at the liner
First of all, check whether the outside and inside of the thermos liner are smooth (whether there are cracks), whether the opening of the liner is smooth, and whether the joint of the liner is intact. Is the vacuum flask stopper completely consistent with the vacuum flask mouth? If it can be completely matched, it means that the bottle stopper is well sealed.
3. Look at the brand
Generally speaking, the choice of raw materials for well-known brands will be more secure, and the description on the product will be more complete. When we choose, we can choose according to the parameters on the manual.