Why refrigerators hum，on toay's moment of science.
今天的科学一刻我们要探讨冰箱会发出声音的原因。
On the recent program we have discussed how fluorocarbon coolant cools your food by coming to a boil in coils hidden in your fridge.
在最近的节目中我们讨论了碳氟化合物冷却剂是如何通过在冰箱内置的盘管中达到沸腾状态来冷却食物的。
How is this possible?
这是如何实现的？
When you boil water on the stove, you supply heat energy by turning on the burner.
在炉子上烧水的时候，你会打开燃灶来提供热量。
In your fridge, liquid coolant boils at very chilly temperatures, but it still requires heat energy.
而在你的冰箱内部，虽然液态冷却剂是在很低的温度下沸腾，但它仍然会需要热能。
The coolant absorbs this heat energy from the air inside the fridge.
冷却剂吸收的热能来自于冰箱内的空气。
By the time all the coolant has boiled and evaporated into gas, the fridge has reached Arctic temperatures.
当冷却剂沸腾并蒸发为气体后，冰箱内的温度就接近北极地区了。
What happens when the temperature starts to rise again?
当温度重新上升的时候会发生什么？
In order to repeat this chilling performance, the gas coolant has to release heat energy and change back to liquid state.
为了重复前面的降温过程，气态的冷凝剂必须释放热能并转化为液态。
To release heat, the coolant is forced into a second set of coils outside the fridge, in back.
而为了释放热能，冷却剂需要被排到冰箱后部裸露在外的螺旋管内。
Sometimes these coils feel pretty warm.
有时候，这些螺旋管摸起来会感觉相当热。
How does the gas coolant that just chilled your fridge make the coils warm?
这些刚才还用来降温的气态冷却剂，现在为何却能使管道发热了呢？
The secret's in the refrigerator's hum.
秘密就在于冰箱的发出的声音。
That humming is a pump that compresses and warms thegas while forcing it into the coils.
这种嗡嗡声来自于用来把冷却剂压缩到外部螺旋管并使它发热的一个压缩泵。
It's like pumping up a bicycle tire; the tire feels warm because you've compressed the air inside.
就像给自行车胎打气一样，轮胎摸起来会有点热，因为你把空气压缩进去了。
Through compression, the gas coolant in the coils has become warmer than room temperature and can now release its heat energy to the air.
通过压缩，螺旋管内气态冷却剂的温度变得比室温更高，这样便可能把热量释放到空气中。
As it releases heat, the gas cools and condenses back to liquid state.
在气体释放热量物同时，它会重新变回液体状态。
So when your fridge hums, it's releasing heat energy and changing fluorocarbon back to liquid state.
当你的冰箱嗡嗡响时，它是在向外释放热量并把碳氟化合物冷却剂重新转为液态。
Then it can cool your food by coming to a boil once more.
这样它就可以再一次通过沸腾给你的食物降温了。
