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科学美国人60秒 SSS 2016-8-13

时间:2016-08-16 08:57:56

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If you've gone shopping for a car lately, you might have noticed that fuel economy—the number of miles per gallon—is creeping up. One reason is a more efficient type of fuel injection, called gas direct injection. It’s a feature of half the new cars sold in the U.S. last year.

如果你最近买了一辆车,你可能已经注意到——燃油经济,每加仑行驶的总英里数正在蠕升。原因之一在于燃油喷射的效率更高,称为缸内喷气。这是去年所出售的一半新车所具有的一大特征。

"With that kind of engine design you can also introduce turbocharging—that's really what it comes down to: more engine power with a smaller engine." Naomi Zimmerman, an air-quality scientist at Carnegie Mellon University—who has never owned a car. "Probably because I did a whole PhD on engine emissions1."

Here's how the two injection methods differ. In the old standard, called "port fuel injection," gas is injected into the air intake2, where it mixes with air before hitting the cylinder3. In direct injection though, as the name implies, the fuel is injected directly into the cylinder. It's more fuel efficient, meaning lower CO2 emissions, which will help slow climate change. But paradoxically, it also emits more particulate4 matter, including black carbon, or soot5—a pollutant6 implicated7 in global warming.

这种类型的引擎设计,也可以引进涡轮增压——这才是真正的原因——更小马力的引擎,更多的发动机功率。内奥米齐默尔曼,卡内基梅隆大学一名空气质量科学家——从未拥有一辆车。“可能是因为我博士研究生阶段做了关于发动机排放的整体研究。这是这两种喷射形式的不同之处。按照旧标准,称之为“气门式燃料喷射”,将气体注入进气口,在冲击汽缸之前与空气混合。然而,直接式燃料喷射,顾名思义,燃料直接注入汽缸,这样更省油,意味着较低的二氧化碳排放,这将有助于减缓气候变化。但是,与此相矛盾的是,也能喷射出更多的颗粒物。包括黑碳或煤灰——与全球变暖有直接关系的污染物。

Zimmerman and her colleagues analyzed8 studies of direct injection engines to see how this pollution tradeoff works out for the climate. "The answer is that it's really complicated and it's not certain." But on average, she says, boosting fuel economy five to nine percent would probably cancel out the warming effects of black soot, and score a net positive for the climate. The findings are in the journal Environmental Science and Technology. [Naomi Zimmerman et al., Assessing the Climate Trade-Offs of Gasoline Direct Injection Engines]

齐默尔曼与她的研究团队对直喷式发动机的研究进行分析以查明这一污染权衡怎样使气候受益。“答案是,这真的很复杂,目前还不能确定。”但平均而言,她表示,将燃油经济性由5%提高到9%,可能会消除黑炭的暖化效应,整体而言对气候有益。该项研究结果发表在《环境科学与技术》杂志上。

The fuel economy goal might be different in places with big temperature swings, and where gasoline has more aromatic9 compounds—which seem to boost black carbon emissions. One place that fits the bill: Canada. “There we might need to be closer to the 10 percent, 15 percent mark in terms of improving fuel economy. Which is actually a very aggressive increase in fuel economy."

燃油经济性目标可能在那些温度波动较大、汽油中含有更多芳香化合物的地方会有所不同——这似乎促进了黑碳排放。刚好符合要求的一个地方:加拿大。在这里,就改善燃油经济性而言,我们可能需要将其提高接近10%,15%,这的确是燃油经济性的巨大极高。

She says one solution that might reduce black carbon emissions is gasoline particulate filters. Which would also screen out particulate matter dangerous to human health. Meaning a win for the planet—and the people who live on it.

她表示减少黑碳排放的一个可行的解决方案是汽油颗粒过滤器,它也可以筛选出对人类健康有危害的颗粒物。这意味着赢得了这个星球——并且人们在这个星球上生活。


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1 emissions 1a87f8769eb755734e056efecb5e2da9     
排放物( emission的名词复数 ); 散发物(尤指气体)
参考例句:
  • Most scientists accept that climate change is linked to carbon emissions. 大多数科学家都相信气候变化与排放的含碳气体有关。
  • Dangerous emissions radiate from plutonium. 危险的辐射物从钚放散出来。
2 intake 44cyQ     
n.吸入,纳入;进气口,入口
参考例句:
  • Reduce your salt intake.减少盐的摄入量。
  • There was a horrified intake of breath from every child.所有的孩子都害怕地倒抽了一口凉气。
3 cylinder rngza     
n.圆筒,柱(面),汽缸
参考例句:
  • What's the volume of this cylinder?这个圆筒的体积有多少?
  • The cylinder is getting too much gas and not enough air.汽缸里汽油太多而空气不足。
4 particulate 4mMzPG     
adj.微小的;n.微粒,粒子
参考例句:
  • A special group was organized to dig up the particulate of the case.成立了一个专门小组来查明该案件的各个细节。
  • Lungs retain relatively insoluble particulate material.肺脏内留有不溶解的颗粒物质。
5 soot ehryH     
n.煤烟,烟尘;vt.熏以煤烟
参考例句:
  • Soot is the product of the imperfect combustion of fuel.煤烟是燃料不完全燃烧的产物。
  • The chimney was choked with soot.烟囱被煤灰堵塞了。
6 pollutant N1Zzy     
n.污染物质,散布污染物质者
参考例句:
  • Coal itself is a heavy pollutant.煤本身就是一种严重的污染物。
  • Carbon dioxide may not be a typical air pollutant.二氧化碳可能不是一种典型的污染物。
7 implicated 8443a53107b44913ed0a3f12cadfa423     
adj.密切关联的;牵涉其中的
参考例句:
  • These groups are very strongly implicated in the violence. 这些组织与这起暴力事件有着极大的关联。 来自《简明英汉词典》
  • Having the stolen goods in his possession implicated him in the robbery. 因藏有赃物使他涉有偷盗的嫌疑。 来自《现代汉英综合大词典》
8 analyzed 483f1acae53789fbee273a644fdcda80     
v.分析( analyze的过去式和过去分词 );分解;解释;对…进行心理分析
参考例句:
  • The doctors analyzed the blood sample for anemia. 医生们分析了贫血的血样。 来自《简明英汉词典》
  • The young man did not analyze the process of his captivation and enrapturement, for love to him was a mystery and could not be analyzed. 这年轻人没有分析自己蛊惑著迷的过程,因为对他来说,爱是个不可分析的迷。 来自《简明英汉词典》
9 aromatic lv9z8     
adj.芳香的,有香味的
参考例句:
  • It has an agreeable aromatic smell.它有一种好闻的香味。
  • It is light,fruity aromatic and a perfect choice for ending a meal.它是口感轻淡,圆润,芳香的,用于结束一顿饭完美的选择。

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