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This is Scientific American — 60-Second Science. I'm Christopher Intagliata.
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 material 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.
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.
Thanks for listening for Scientific American — 60-Second Science Science. I'm Christopher Intagliata.
参考译文
这里是科学美国人——60秒科学
你或许见过希腊村庄的照片,那里的每座房子都被粉刷成亮白色 。这种颜色的漆可以反射来自地中海的强烈阳光 。还可以有效避免房屋被太阳炙烤 。但是,这种漆却不能为房子降温 。
要追溯原因,就要考虑一下白漆的作用 。科罗拉多大学的光学科学家尹晓波描述称:“白漆能反射阳光,也能反射辐射 。”看起来能反射所有进来的光线是一件好事 。但是,这种益处是有限的 。尹晓波表示,因为这也表明房屋“不能释放太多能量 。”如果房子能以红外辐射的方式释放更多能量——也就是热量——那你就能免费享用空调了 。
所以尹晓东和他的同事制造出了一种既可以反射可见光又可以释放红外波长的材料 。这一性质使材料具有降温功能 。这种材料有两层:上层是聚合物,其中布满了直径仅有8微米的玻璃珠,这样就可以吸收并释放红外线辐射 。下层是镀银层 。
这种材料能反射96%的太阳辐射——这只是对白漆和银漆进行了略微的改进 。但是其变革性的成分在于:这种材料拥有每平方米约100瓦的冷却能力 。也就是说:它可以让一煎锅水的温度降至比周围环境温度低15华氏度左右 。即使在烈日下也能做到 。该研究结果发表在《科学》期刊上 。
这一冷却水实例可以广泛应用到各个地方 。“这水可以用来给房子降温,降低数据中心的温度,甚至用来降低热力发电厂的温度 。”尹晓波在科伦多大学的同事杨荣归如是说 。他还表示,这种降温方法价格低廉 。不过,不要将这种材料直接放到屋顶上 。“这种材料冬天也会给房子降温 。你可不想冬天也降温吧 。”肯定不想,那可不好 。
谢谢大家收听科学美国人——60秒科学 。我是克里斯托弗·因塔利亚塔 。
译文为可可英语翻译,未经授权请勿转载!
重点讲解
重点讲解:
1. keep sb. from doing sth. 阻止(或防止、阻碍)…做;
例句:She said that even though people may try to control their expressions, most are not able to keep their feelings from showing on their faces.
她说,即使人们试图控制自己的表达方式,但是大多数人都无法阻止他们把自己的感受反应到面部表情上 。
2. heat up 变热;
例句:The room was cold when we arrived, but soon began to heat up.
我们到达时房间里很冷,但很快就变热了起来 。
3. be packed with 挤满;塞满;
例句:The plane was packed with Dutch holidaymakers.
飞机上载满了荷兰的度假者 。
4. cool down (使)变凉;(使)冷却;(使)降温;
例句:Avoid putting your car away until the engine has cooled down.
在发动机冷却之前不要把车开进车库里 。