By the mid-1930s, most refrigerators and air conditioners used chlorofluorocarbons – sometimes known under the trademark Freon – which were non-flammable, and safer to use.

到了20世纪30年代中期，大多数冰箱和空调都使用了氟氯化碳，有时以氟利昂的商标命名，它们不易燃，使用起来更安全。

I was working on a new type of heat pump that would use water as a working fluid instead of Freon.

JOHNSON：我正在研究一种新型热泵，它使用水而不是氟利昂作为工作流体。