And so instead of defining efficiency the way you've got it written there, I'm going to define what's called something different for a refrigerator which is called the coefficient of performance.

现在我们不用,效率的那个定义，我给出一个,有关制冷机的,新的定义,叫做制冷系数。

麻省理工公开课 - 热力学与动力学课程节选

So you know, what the second law is doing, in other words, it's putting these restrictions on how well or how effectively we can convert heat into work in the case of the engine, or work into heat extracted in the case of a refrigerator.

你们知道，在热机中，热力学第二定律的作用，换句话说，就是给热量,转化为功的效率,施加限制,或在制冷剂中，对抽取热量,进行限制。

麻省理工公开课 - 热力学与动力学课程节选