英语听力文摘 English Digest 532、有一种沸腾能冷却你的食物！

 　　The Rolling Boil That Cools Your Food

 

　　When you think of something boiling, you probably picture a pot on the stove, but there’s another kitchen appliance that brings liquid to a boil, not to heat food, but cool it. It sounds crazy, but household refrigerators keep food cold by bringing liquid fluorocarbon to a boil.

 

　　How Does This Work?

 

　　Fluorocarbon coolant flows through two sets of coils in your fridge, absorbing heat inside and releasing it outside, into your kitchen. You’ve probably seen one set of coils behind the fridge, in back. That’s where heat’s released. Hidden inside the fridge is the other set of coils, where heat’s absorbed.

 

　　It’s inside these hidden coils that liquid coolant comes to a boil. What makes the coolant boil? The secret is in the relationship between pressure and boiling point. When pressure changes, so does the temperature at which a substance comes to a boil.

 

　　As the liquid coolant passes through a valve into the hidden coils, the pressure drops. This pressure change makes the coolant’s boiling point drop below the chilly¹ temperature in the fridge. So, some of the coolant boils immediately and evaporates into a gas inside the coil. Evaporation² uses up lots of heat energy. As the coolant continues to boil and evaporate, it absorbs heat from the air in the fridge, making it even colder inside. So that’s how boiling fluorocarbon cools your food.

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。