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

This one turns out to be the heat capacity, and this one turns out to be something that we measure in the Joule-free expansion.

其实，这就是热容，这是焦耳自由膨胀实验中,我们要测量的物理量。

麻省理工公开课 - 热力学与动力学课程节选