Study of the structure and properties of hot water bottles

Normal glass, high-quality use of quartz glass.

In the past, silver plating was used as a reflective layer, but now aluminum is generally used as a reflective layer.

Between the inner and outer layers there are three asbestos mats. The air between the inner and outer layers and its thinness prevent the air from conducting heat.

Ordinary glass, but there is a laminated layer inside, and the laminated layer is mirrored (aluminum, silver, etc.), and the interior is vacuumed.

Reduce conduction, convection, and radiation three modes of heat propagation.

That's when the bottle is being shaped.

Since the bottle is made of glass.

That protrusion is the final connector.

Connections to the machine.

Characteristics: Glass, double-layered structure, internally vacuumed and plated with mercury.

Purpose: To reduce heat conduction and improve heat retention.

When the bottle is shaped, it is hollow and leaves a hole. After completion, it is vacuumed and sealed with wax.

It's usually made of glass, with a sandwich in the middle, and a vacuum between the sandwiches is silver-plated.

It is normal glass, high-quality use quartz glass.

One way to make a container like a thermos is to take a jar and wrap it in foam insulation. Insulation works for two reasons. First of all, the plastic in the foam is a poor conductor of heat.

Secondly, the air trapped in the foam is less conducive to heat conduction. As a result, conductivity is reduced. Since the air is separated into extremely small bubbles, the foam insulation also plays a large role in eliminating convection inside the foam.

As a result, there is very little heat transfer through the foam. It turns out that there is a better thermal insulation than foam – vacuum. Vacuum means there are no atoms.

The complete vacuum "does not contain any atoms. It is almost impossible to achieve a complete vacuum, but it is possible to achieve close to a vacuum, and without atoms, conduction and convection can be completely eliminated.

There is a glass bottle in the thermos that is vacuumed. The inside of the thermos is a layer of glass, and around the glass is a vacuum. Glass bottles are prone to breakage, so wrap them inside a plastic or metal case. Many thermos can actually be unscrewed and the glass bottle can be removed.

The thermos goes one step further. The glass is silver-plated (like a mirror) to reduce infrared radiation. The combination of vacuum and silver plating greatly reduces heat transfer due to convection, conduction, and radiation.

So why does the contents of a thermos end up cooling down? In the diagram, you can see that there are two paths for heat transfer. The larger of these is the cork, and the other is the glass, which creates a heat transfer path where the inner and outer walls of the thermos top meet.

While heat transfer through these paths is rare, it is not none.

Does a thermos know if the liquid inside is hot or cold? I don't know. All the thermos does is limit the heat transfer that takes place through the walls of the thermos. That will keep the liquid inside the thermos almost the same temperature for a long time, whether hot or cold.