Real refrigerators actually work with liquids that go into gases so use the latent heat of the liquid, so it doesn't really work like the Joule-Thomson expansion. So this is real.

液体变成气体来工作,以运用液体的潜热，所以这不是,真正像焦耳-汤姆逊膨胀一样工作,这是真实的气体，不像焦耳。

麻省理工公开课 - 热力学与动力学课程节选

In this class here, we're going to stick to one kind of work which is expansion work.

推动我的粉笔,我就对它做了功。

麻省理工公开课 - 热力学与动力学课程节选