首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
考研
At the moment, there are two reliable ways to make electricity from sunlight.【F1】You can use a panel of solar cells to create th
At the moment, there are two reliable ways to make electricity from sunlight.【F1】You can use a panel of solar cells to create th
admin
2014-10-27
58
问题
At the moment, there are two reliable ways to make electricity from sunlight.【F1】
You can use a panel of solar cells to create the current directly, by liberating electrons from a semiconducting material such as silicon. Or you can concentrate the sun’s rays using mirrors, boil water with them, and employ the steam to drive a generator.
Both work. But both are expensive. Gang Chen of the Massachusetts Institute of Technology and Zhifeng Ren of Boston College therefore propose, in a paper in Nature Materials, an alternative. They suggest that a phenomenon called the thermoelectric effect might be used instead—and they have built a prototype to show that the idea is practical.
In their view, three things are needed to create a workable solar-thermoelectric device. The first is to make sure that most of the sunlight which falls on it is absorbed, rather than being reflected. The second is to choose a thermoelectric material which conducts heat badly(so that different parts remain at different temperatures)but electricity well.【F2】
The third is to be certain that the temperature gradient which that badly conducting material creates is not frittered away by poor design.
The two researchers overcame these challenges through clever engineering. The first they dealt with by coating the top of the device with oxides of hafnium, molybdenum and titanium, in layers about 100 nanometres thick.【F3】
These layers acted like the anti-reflective coatings on spectacle lenses and caused almost all the sunlight falling on the device to be absorbed.
The second desideratum, of low thermal and high electrical conductivity, was achieved by dividing the bismuth telluride into pellets a few nanometres across.【F4】
That does not affect their electrical conductivity, but nanoscale particles like this are known to scatter and obstruct the passage of heat through imperfectly understood quantum-mechanical processes.
The third objective, efficient design, involved sandwiching the nanostructured bismuth telluride between two copper plates and then enclosing the upper plate(the one coated with the light-absorbing oxides)and the bismuth telluride in a vacuum. The copper plates conducted heat rapidly to and from the bismuth telluride, thus maintaining the temperature difference. The vacuum stopped the apparatus losing heat by convection. The upshot was a device that converts 4.6% of incident sunlight into electricity.【F5】
That is not great compared with the 20% and more achieved by a silicon-based solar cell, the 40% managed by a solar-thermal turbine, or even the 18-20% of one of the new generation of cheap and cheerful thin-film solar cells.
But it is enough, Dr Chen reckons, for the process to be worth considering for mass production.
【F5】
选项
答案
以硅晶为基础的太阳能电池的转化率为20%甚至以上,太阳能热力涡轮的为40%,就连一种新一代价廉物美的薄膜太阳能电池的转化率也能达到18%一20%。
解析
转载请注明原文地址:https://kaotiyun.com/show/SfK4777K
0
考研英语一
相关试题推荐
AnexpressionusedbyAmericansforabout100yearsis"topassthebuck".Itmeansrefusingtotakeresponsibility,lettingothe
AnexpressionusedbyAmericansforabout100yearsis"topassthebuck".Itmeansrefusingtotakeresponsibility,lettingothe
Everyonehassufferedfromheadaches,but【C1】______recentlymedicalresearcherswerenotcertainwhatcausedthem.Blewresearch
Everyonehassufferedfromheadaches,but【C1】______recentlymedicalresearcherswerenotcertainwhatcausedthem.Blewresearch
Hereissomeadviceonfoodshopping.The【C1】______familyspendsaboutone-sixthofitsincome【C2】______food.Becausefoodisex
Itdoesn’tmatterwhichroomafamilychoosesto【C1】______in.It【C2】______beafavoritecomerofthekitchen,orawoodpanelled
Itdoesn’tmatterwhichroomafamilychoosesto【C1】______in.It【C2】______beafavoritecomerofthekitchen,orawoodpanelled
Accordingtopsychoanalysis,aperson’sattentionisattracted______bytheintensityofdifferentsignals______bytheircontext
DamIt’simpossibletowriteabouthowhumanactivitiesarealteringtheclimate,thattrivialhumanitycannotpossiblyalte
Writeanannouncementtoyourschoolmates,informingthemanoff-campusactivityonSeptember18th.Youshouldwriteabout100
随机试题
甲创作完成了专著《传习录解读》,乙未经甲的同意将其改编成传记小说《王阳明与传习录》。丙自行将乙出版的《王阳明与传习录》翻译成盲文并出版发行。对此,下列说法错误的是()。
肝转移癌表现为不规则强回声,后伴声影,关于可能的原发癌,说法错误的是
患者有内痔史,近日大便带血,血色鲜红,间或有便后滴血,肛门瘙痒,舌红,苔薄黄,脉浮数。其治法是
糖皮质激素对血液成分的影响有()。
关于原油集输站、集输管道防火、防爆的基本要求,下列说法中,不正确的是()。
关于Horner’s综合征的描述,以下不正确的是()。
A、 B、 C、 D、 B考虑图形中的封闭区域数。每行或每列图形的封闭区域数依次递增,应选择有6个封闭区域数的图形。
四位球迷在某球赛的晋级赛开始之前对几个队伍的赛况进行预测,他们比较关注其中的两支球队,分别作了如下预测:方某说:如果甲队不能晋级,那么乙队也不能晋级。白某说:不管甲队能不能晋级,乙队都不能晋级。夏某说:乙队能晋级,但甲队不能晋级。邓某说:我看这几支
()科举考试被废除。
Theworkwasalmostcompletewhenwereceivedtheorderto______nofurtherwithit.
最新回复
(
0
)