How does an air conditioner actually work? - Anna Rothschild

翻译人员: Mina Liu 校对人员: suya f.

Typically, with any piece of technology, you get out what you put in.

通常，使用任何一项技术， 你投入的东西都会得到回报。

Pump one unit of energy into an electric toaster

将一个单位的能量输入烤面包机中，

and you get about one out in the form of heat.

会得到大约一个单位的熱能。

That’s just the first law of thermodynamics:

这是热力学的第一定律：

energy has to be conserved.

能量必须守恒。

But there's a piece of technology called a heat pump,

但是有一种叫做「热泵」的技术，

where for every bit of energy you put in, you get 3 to 5 times as much heat out.

當你投入一点能量， 就会获得 3 到 5 倍热量的反馈。

What wizardry is this?

这是什么奇妙的方法？

Heat pumps have been hailed as a climate-friendly heating solution

热泵被誉为传统加热器的 气候友好型供暖系統解决方案，

to traditional heaters,

热泵被誉为传统加热器的 气候友好型加热系統解决方案，

most of which operate by burning fossil fuels.

其中，大多数的加热器 通过燃烧化石燃料來运作。

So much so that in 2021,

以至于在 2021 年，

heating buildings was responsible for about 10%

全球与能源相关的二氧化碳排放量中，

of global energy-related CO2 emissions.

建築的供暖约占 10％ 的排放量。

Heat pumps reduce emissions in two ways—

热泵以两种方式來减少排放——

first, they run on electricity,

第一，热泵依靠电力來运行，

meaning less fossil fuel use as grids make the switch to renewable energy.

表示随着化石燃料的使用减少 讓输电网络转向使用可再生能源。

And second, they're more efficient than their counterparts,

第二，热泵比同类产品更高效，

using less energy to produce the same amount of heat.

它能用更少的耗能来生产相同的热量。

Where a typical oil or gas boiler is, at best, about 90% efficient,

如果典型的石油或天然气锅炉 的效率充其量约为 90％

some heat pumps can achieve 500% efficiency.

则某些热泵的效率可以达到 500％。

Heat pumps rely on the same technology as air conditioners.

热泵与空调使用相同的技术。

And in fact, they often double as air conditioners,

实际上，热泵也經常兼作空调，

heating your home in the winter and cooling it in the summer.

在冬天为房屋供暖， 在夏天为房屋降温。

How? Air conditioners take heat from your home and move it outside.

这如何运作的？

空调将室内的热量带走并转移到室外。

To do so, they harness the second law of thermodynamics.

为实现这方法， 热泵利用了热力学第二定律。

That’s the one that says that heat will always move from a hotter object

它阐述热量都会从 较高温的物体转移到较低温的物体

to a colder one.

它阐述热量都会从 较高温的物体转移到较低温的物体

When you turn on your A/C,

当你打开空调时

a fan blows the hot air from your home over coils

风扇会将家中的热空气吹过含有

containing a substance called a refrigerant.

一种叫制冷剂的物质的线圈。

A refrigerant’s molecules turn to gas at relatively low temperatures,

制冷剂的分子 在相对低温下就会转变成气体，

so as it collects thermal energy from the hot air in your home, it boils.

所以当它从家中的 热空气中吸收热能时，

它就会沸腾。

Then, it passes into a compressor,

接著，它推进到压缩机，

which pushes the gas molecules closer together,

压缩机会将气体分子推得更紧密

heating them up even more.

以进一步加热制冷剂的氣體分子。

Now that gas is hot— way hotter than the outside air.

现在，这些气体分子很烫—— 比外面的空气要热得多。

So when a fan blows over the refrigerant,

因此，当风扇吹过制冷剂时，

thermal energy transfers to the comparatively cold air outside.

热能会转移到户外相对较冷的空气中。

As the refrigerant releases heat, it starts to liquefy.

当制冷剂释放热量时，它开始液化。

It goes through an expansion valve, which decreases the pressure,

它穿过膨胀阀以降低压力，

causing it to get even colder.

讓制冷剂变得更冷。

Now, it’s ready to pick up more heat from your house and start the cycle again.

这时候，它已经准备好从屋内 吸收更多热量并再次开始循环了。

In winter, heat pumps work exactly the same way.

在冬天，热泵的运作方式完全相同。

But this time they pick up heat from outside and move it into your home.

但这次，热泵从外面吸收热量 并将其转移到家中。

Of course, it’s sometimes freezing outside when you want to use your heater.

当然，当你想使用暖气机时， 外面有时很冷。

But the air doesn’t need to be warm—

但是空气不一定需要是暖和的——

it just needs to be warmer than the refrigerant to transfer its heat.

空氣只需要比 制冷剂更温暖就能传递热量。

All this sounds great, but for now there are some drawbacks to this technology.

这些听起来挺不错的， 但目前这项技术有一些缺点。

First, refrigerants can be potent greenhouse gases.

首先，制冷剂可能是强有力的温室气体。

Hydrofluorocarbons are some of the most popular refrigerants.

氢氟碳化物是一些最普遍的制冷剂。

But a single hydrofluorocarbon molecule can have 2,000 times

但是，单个氢氟碳化物分子 对全球变暖的影响

the global warming impact of CO2.

是二氧化碳的 2,000 倍。

While in use, the refrigerant stays contained in a closed loop.

在使用时，制冷剂保持 在密闭的循环状态中。

But when heat pumps, A/Cs, and refrigerators are improperly installed

但是当热泵、 空调和冰箱安装不当時，

or thrown into landfills, the refrigerant can leak out.

或被丢到垃圾填埋场时， 制冷剂可能会泄漏出。

So scientists are trying to create new refrigerants

因此，科学家们正在尝试创造 对环境更友善的新制冷剂

that are better for the environment.

因此，科学家们正在尝试创造 对环境更友善的新制冷剂

Also, the colder it is outside,

此外，只要户外越冷，

the less efficient an air-to-air heat pump will be.

空气源热泵的效率就越低。

Nevertheless, over half the buildings in icy Norway use heat pumps.

尽管如此，寒冷的挪威 有一半以上的建筑物使用热泵。

Some people there have opted for pumps that draw heat from under the ground,

那里有些人选择使用 从地下吸收热量的热泵，

which stays more consistently warm, rather than heat from the air.

这样比从空气中吸收热量 可以更持久地保持温暖。

Finally, there's the cost.

最后是成本的考量。

In the US, installing a small heat pump usually costs several thousand dollars,

在美国，安装小型热泵 通常要花费数千美元，

though some people need more powerful systems,

尽管有些人需要更强大的系统，

depending on the size of their home or the temperature in winter.

具体取决于房屋的大小或冬天的气温。

Often they’re only a little more expensive than installing a new A/C system,

通常，安装热泵只比 安装新的空调系统贵一点，

and the heat pump can save money on utilities in the long run.

而且长期来看，热泵可以节省电费。

But replacing a working system requires an upfront investment

但是，更换运作系统需要前期的投资，

that a lot of people just don’t have.

而很多人没有这个能力。

Still, as the risks of climate change loom,

尽管如此，随着气候变化 的风险迫在眉睫，

many countries are offering subsidies to help with the costs.

许多国家提供补贴 以帮助降低更换費用。

And some cities are creatively harnessing seas, sewage, and data centers

有些城市正在创造性地利用 海洋、污水和数据中心

as heat sources, using heat pumps in manufacturing,

作为热源、在制造业中使用热泵、

and even creating giant heat pumps for entire districts.

甚至为整个地区制造巨型热泵。

So, are heat pumps actually breaking the first law of thermodynamics?

那么，热泵真的违反了 热力学第一定律吗？

Of course not.

当然不是。

They’re just not using their electricity to make heat.

热泵只是没有用 电来发热。

They're using it to power the compressor and spin the fans.

热泵用电来驱动压缩机和旋转风扇。

They get the extra energy for free— from heat in the air or underground.

热泵从空气中或地下的热能中 免费获得额外的能量。

Which is how, by putting in 1 unit of energy,

正是这样，藉由输入一个单位的能量，

you get 3 to 5 units of heat out.

就可以获得 3 到 5 个单位的热量。

Seems like magic, but it's just physics.

看起来像魔法，但这只是物理学。