Cooling Coat Chills in the Sunlight

中文批注

这篇文章主要是关于一种在太阳光下仍能保持cooling的一种涂层。这是为什么呢？因为用吸收再放射的方式。但这种涂层能做的只是防止房子在太阳底下变热，但是涂料本身并没有制冷的功能。

这篇文章属于”科技感”较重的文章，大家可能会有不少单词看不懂，或者有些意义不太明白。不用担心，AIL小编已经替大家整理一些可能会存在的生词，就在下面的Key Vocabulary中哦！如果有不认识的单词，就赶紧对照一下，然后再看文章进行理解。对于目标79的同学来说，如果除了以下的单词表中还有些许不认识的单词，那可就不太应该了哦！要抓紧背诵单词啦！

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[Key Vocabulary]

Intense: adj. 强烈的，紧张的，非常的

Mediterranean: 地中海

Actively: adv. 积极地，活跃地

Optical: adj. 光学的，眼睛的

Rays: n. 射线，光线

Infrared: n. 红外线

Wavelength: 【物】波长

Emit: Vt. 发出，放射

Polymer: n. 【高分子】聚合物

Bead: n. 珠子，念珠

Fahrenheit: 华氏温度

Ambient: n. 周围环境; adj. 周围的，环绕的

Thermoelectric: 【电】热电的

Full Transcript

A thin film coating can chill a vat of water to 15 degress Fahrenheit cooler than its surroundings, by absorbing—and then emitting—the sun’s infrared rays. Christopher Intagliata reports.

You’ve probably seen pictures of Greek villages, where every house is painted bright white. The paint reflects the intense sunlight of the Mediterranean. And it works pretty well to keep the houses from heating up in the sun. But it doesn’t actively cool them.

To understand why, consider what the white paint does. Here’s how optical scientist Xiaobo Yin of the University of Colorado describes it: “It’s a mirror for the sunlight, it’s also a mirror for the radiation as well.” And it might seem like reflecting all those incoming rays would be a good thing. But the benefit is limited. Because what it really means, Yin says, is that the houses, well, “they don’t release much energy.” Release more energy, again in the form of infrared radiation, aka heat—and you effectively get free A/C.

So Yin and his colleagues built a material that does exactly that: reflects visible light, but also emits infrared wavelengths. Which gives it the power to actually cool. It’s two layers: a top layer of polymer, packed with glass beads just eight microns across—so they can absorb and then emit infrared radiation. And a silver coating on the bottom.

The coating reflects 96 percent of solar radiation—a slight improvement on white and silver paint. But the game-changing part: it also has a cooling power of about 100 watts per square meter. Translation: enough to cool a frying-pan-sized amount of water to about 15 degrees Fahrenheit cooler than ambient temps. Even while sitting in the sun. The finding is in the journal Science. [Yao Zhai et al., Scalable-manufactured randomized glass-polymer hybrid metamaterial for day-time radiative cooling]

That cool water example has wide applications. “This water can be used to cool a house, cool a data center, or even cool a thermoelectric power plant.” That’s Yin’s colleague at the University of Colorado, Ronggui Yang. And he says it’s a cheap way to cool things down. Just don’t put the material directly on your roof. “It also cools down during the wintertime. And you do not want that to happen.” No. Definitely… not cool.

—Christopher Intagliata

(Source: https://www.scientificamerican.com/podcast/episode/cool-coating-chills-in-sunlight/)