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
2017-06-25
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.
【F2】
选项
答案
第三是确保那种导热性差的材料产生的温度变化不会因为设计缺陷而白白浪费。
解析
转载请注明原文地址:https://kaotiyun.com/show/YPbZ777K
0
考研英语一
相关试题推荐
Justaseachweddingcreatespotentialbusinessfordivorcelawyers,soeachengagementgivesinsurersachancetodrumupbusin
Atthemoment,therearetworeliablewaystomakeelectricityfromsunlight.【F1】Youcanuseapanelofsolarcellstocreateth
DespiteincreasedairportsecuritysinceSeptember11th,2001,thetechnologytoscanbothpassengersandbaggageforweaponsan
AnyAmericanwhohasboughtapackofcigarettessincethemid-’60smighthaveseenthehealthwarnings.Itsays,"SURGEONGENER
Theauthorofsomefortynovels,anumberofplays,volumesofverse,historical,criticalandautobiographicalworks,aneditor
TheDemocraticPartyisthepartyoflongestcontinuousexistence.
Ironismoreusefulthananyothermetal.
Thisroomisthreetimeslargerthanthatone.
动物的权利问题——1997年英译汉及详解Doanimalshaverights?Thisishowthequestionisusuallyput.Itsoundslikeauseful,ground-clearing
Theplanetsseemedlikeprettysmallplaces.Atthesametime,Earthseemedalotlargerthanitdoesnow.Noonehadeverseen
随机试题
TheStudioSchoolIntroduction.TheStudioSchoolcaninnovateour【T1】________schooling..Theideacomesfroman
下列关于消化道出血的临床表现,不正确的是
A.头痛而眩,面红口苦B.头痛不甚,气短乏力C.头痛而胀,甚则头胀如裂D.恶寒畏风,遇风尤剧E.头痛经久不愈,痛处固定不移患者,男,57岁。头部有外伤史。辨证为瘀血头痛,其临床特点是
当桥梁的主要构件有大的缺损,严重影响桥梁使用功能;或影响承载能力,不能保证正常使用。则桥梁总体技术状况等级为()。
以下叙述错误的是()。
二手车是指从办理完机动车注册登记手续到规定报废年限一年之前进行所有权变更的汽车。()
某些普通初中为了培养尖子生,选拔出学习基础好的年级前50名的学生,设立奥赛班、火箭班等重点班,挑选教学能力优秀的老师进行辅导,提高他们的学习成绩,剩下的学生都分到普通班。对这些初中的做法,下列观点正确的是()。
认真贯彻严肃与谨慎相结合的政策就是要坚持()。
(2010下集管)我国颁布的《大楼通信综合布线系统YD/T926》的适用范围是跨度不超过3000米、建筑面积不超过______万平方米的布线区域。
(演示文稿题)中国注册税务师协会宣传处王干事正在准备一份介绍本协会的演示文稿,按照下列要求帮助王干事组织材料完成演示文稿的整合制作,完成后的演示文稿共包含15张幻灯片,且没有空白幻灯片。将第3~8张、9~12张幻灯片分别组织为一节,节名依次为“概况”“
最新回复
(
0
)