You take a throttle valve, which consists of some sort of porous plug between two cylinders that is insulated. There is insulation here.

有一个节流阀，它由一些多孔的塞子组成,这些多孔塞在两个绝热的汽缸之中,这里是绝热的，底下也是绝热的。

麻省理工公开课 - 热力学与动力学课程节选