听力文摘：有一种沸腾能冷却你的食物

When you think of something boiling, you probably picture a pot on the stove,

一提到沸腾的事物，你的脑海里可能就会浮现出水壶被放在炉子上的画面。

but there'sanother kitchen appliance that brings liquid to a boil, not to heat food, but cool it.

但是，有一种厨具可以使液体沸腾，但不是为了加热食物，而是用于冷却食物。

It sounds crazy,but household refrigerators keep food cold by bringing liquid fluorocarbon to a boil.

这事儿听起来很不可思议，但是家用冰箱就是通过使碳氟化物沸腾来冷藏食物。

How Does This Work?

这其中的原理是什么呢？

Fluorocarbon coolant flows through two sets of coils in your fridge, absorbing heat inside andreleasing it outside, into your kitchen.

碳氟化物冷却剂流经冰箱的两组盘管，吸收冰箱内部的热量并将其释放到外部。

You've probably seen one set of coils behind the fridge, in back.

你可能看到在冰箱后侧有一组一组盘管，

That's where heat's released.

热量就是在那里被散发。

Hidden inside the fridge is the other set of coils, where heat'sabsorbed.

而藏在冰箱内部的另一组盘管则是用来吸收热量的。

It's inside these hidden coils that liquid coolant comes to a boil.

就是在这组内置盘管里，液态冷却剂会沸腾。

What makes the coolant boil?

是什么使冷却剂沸腾的呢？

The secret is in the relationship between pressure and boiling point.

答案在于压强和沸点之间的关系。

When pressure changes, so does the temperature at which a substance comes to a boil.

当压强发生改变，物质的沸点也会跟着变化。

As the liquid coolant passes through a valve into the hidden coils, the pressure drops.

随着液体冷却剂经过一个阀门进入内置盘管，压强就会降低。

This pressure change makes the coolant's boiling point drop below the chilly¹ temperature in the fridge.

压强的变化使冷却剂的沸点降到比冰箱内部的低温还要低。

So, some of the coolant boils immediately and evaporates into a gas inside the coil.

这样，部分冷却剂立即沸腾，在盘管内汽化。

Evaporation² uses up lots of heat energy.

汽化作用会消耗掉大部分热能。

As the coolant continues to boil and evaporate, it absorbs heat fromthe air in the fridge, making it even colder inside.

随着冷却剂不停地沸腾汽化，冰箱中空气的热量被吸收，使得冰箱内部温度更低。

So that's how boiling fluorocarbon cools your food.

沸腾的碳氟化物就是这样冷却了食物。

1 chilly   

adj.凉快的，寒冷的

参考例句：

• I feel chilly without a coat.我由于没有穿大衣而感到凉飕飕的。
• I grew chilly when the fire went out.炉火熄灭后，寒气逼人。

2 evaporation   

n.蒸发，消失

参考例句：

• Be careful not to lose too much liquid by evaporation.小心不要因蒸发失去太多水分。
• Our bodies can sweat,thereby losing heat by evaporation.我们的身体能出汗，由此可以蒸发散热。