How Does Vacuum Insulation in a Thermos Work?

Vacuum insulation in a thermos is one of the best ways to keep your coffee hot for a long time. On the surface, the principle seems relatively simple. The vacuum is there to prevent the heat from escaping and cold from coming in. But there is some serious physics going on under the lid.

那么，真空绝缘材料如何工作？本文仔细研究了热量传播的方式，咖啡变冷的原因以及真空绝缘的内部工作。

真空绝缘材料如何工作？- 热旅行指南

There are three basic ways heat travels – conduction, convection, and radiation. Here is a quick overview of all three principles.

Conduction

Conduction happens when two objects touch. To be precise, heat moves from a hot object or a liquid onto a cold one when they come in contact.

对流

For convection to occur, the two objects don’t need to be in direct contact. It is best to use a fan heater as an example to describe how this works. As the fan blows, the hot air pushes the cold air and rises up. In other words, the hot air sits higher in your room and cold air gets nearer to the floor. (1)

Radiation

Because their atoms get additional energy from heat, hot objects emit light before quickly reverting to their usual state. Sometimes you cannot see the light but can still feel the heat. This is called infrared radiation. For example, you can feel the radiation from an incandescent lamp. (2)

Smoking hot coffee might emit heat from a cup, but you shouldn’t feel any heat escaping with a vacuum insulation thermos.

How Does Vacuum Insulation Work in Your Thermos?

要了解真空热水瓶的内部工作，最好看一下其组件。在外部，热水瓶采用螺丝钉盖和由不锈钢或塑料制成的外壳。套管下方有两层玻璃或不锈钢。

The vacuum sits between the first (outer) glass layer which features a reflective coating and the second (inner) layer made of glass or stainless steel. These layers are fused at the top to ensure a tight seal. Plus, there are supports at the bottom to prevent wiggling. There might also be extra insulation between the outer case and the glass layers to protect the inner glass from fractures and damage in case you drop the thermos.

说并完成所有操作后，将在那里进行真空隔热的热水瓶的每个设计元件，以防止任何类型的传热。确切地说，由于真空，不应有任何传导。顶部的螺旋盖阻止了对流，而反射涂层将辐射保持在内部腔室内。

如报价所示，如果您想保持咖啡冷，相同的原理就像魅力一样。这次，热水机元素防止热量渗入并保留在内部真空瓶中的寒冷。（（3)

为什么真空绝缘材料对旅行杯很重要？

简单地说,真空绝缘b是很重要的ecause it is the best way to keep your coffee hot for hours on end. But why does coffee get cold in the first place?

The answer lies in the difference between the temperature of your coffee and room temperature. The ideal coffee brewing temperature is 195°F to 205°F. In fact, the best brews are very close to 205°F. However, the temperature of your room is usually around 70°F. Due to the great difference between the two, the heat quickly moves from the pot or cup into the room.

But if you pour the coffee into a vacuum-insulated travel mug, you prevent the rapid heat transfer via convection, conduction, or radiation. This way, your coffee should still be smoking when you open the mug after a few hours. Not sure which travel mug to pick? See our pick for the最好的旅行咖啡杯在这里.

Final Thoughts

The way vacuum insulation works boils down to basic physics and clever design. That said, some vacuum-insulated mugs retain heat better than others. As such, thebest coffee thermosesare usually from brands that have veritable track records.

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