It's insulated. It's a closed system. In fact, it's an isolated system. There's no energy or matter that can go through that boundary.

系统指的，是盒子里的东西,它是封闭孤立的。

麻省理工公开课 - 热力学与动力学课程节选

The closed system allows energy to transfer through the boundary but not mass.

闭系允许能量通过它的边界传递,但质量不行。

麻省理工公开课 - 热力学与动力学课程节选

So a closed system would be, for instance, a glass of ice water with an ice cube in it, with the lid on top.

因此闭系可以是，比如说，一杯放了,一个冰块的冰水，顶上加了盖子。

麻省理工公开课 - 热力学与动力学课程节选

It's a closed system, so the number moles doesn't change.

这是一个封闭系统，因此摩尔量不会改变。

麻省理工公开课 - 热力学与动力学课程节选

And that's the closed system.

这就是闭系。

麻省理工公开课 - 热力学与动力学课程节选