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英文阅读资料:道路照明技术将采用低耗能技术

(2010-10-22 12:24:40)
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分类: 日积月累

Low-Energy LED Lighting Is “Streets Ahead”

英文阅读资料:道路照明技术将采用低耗能技术

more durable, low-energy street lighting - using LED (light-emitting diode) technology - could result from joint research between Manchester University and the Dialight Lumidrives company. The picture shows Regensburg, Germany, where the coloured light column (not the top white light) consists of LED units from Dialight.

BETTER ways to exploit the advantages of LED (light-emitting diode) technology in street lighting are expected to emerge from collaboration between university researchers and an LED lighting specialist company, both in the UK.

LEDs first appeared in digital watches and calculators in the 1970s. Today, the technology has progressed to the point where it can be used to create durable and community-friendly, low-energy street lighting.

The benefits include long-life expectancy (up to 100,000 hours) together with increasingly high-light output in relation to their size and energy consumption, making LEDs a realistic alternative to conventional sodium vapour units for general and directional lighting. And because LEDs are so small, the possibilities for manufacturers to create sleeker, smaller, lightweight luminaries are greatly extended.

Importantly, LEDs are also environmentally friendly and safe. They contain no glass, filaments or mercury and so can experience none of the exploding failures associated with halogen and HID (high intensity discharge) lamps.

And they are free from the cost and restrictions of mercury disposal that is involved with sodium vapour units. Operating at low-voltage direct current ensures complete consumer safety. Coloured LED modules are very vivid and even more energy-efficient than white light units.

In the latest joint project between the University of Manchester, northern England, and LED lighting specialist Dialight Lumidrives - a company founded by a successful former student of the university - researchers in the School of Electrical & Electronic Engineering are using their expertise to investigate how tightly packed groups of LEDs can be made to work safely and reliably.

Lighting solutions that use LEDs in this way have the potential to reduce energy consumption by 25-50 per cent, depending on the application. But thermal and electrical issues at lighting levels of 12,000 lumens and above (a typical 60w household light bulb produces 800 lumens) are barriers to the wider adoption of LED technology.

The university engineers will be working with the York-based Dialight Lumidrives to tackle tough issues such as the amount of heat generated by LEDs packed closely together. Because the LED modules will be used outside, they will need to consider practical environmental factors, such as the possibility of birds nesting over a vital heatsink.

Another hurdle is presented by the regulations that govern aspects such as glare and light pollution; directing the LED light sources specifically on to the required area will form a serious challenge.

The one-year project has been funded by a grant of 175,000 pounds from the UK government, matched by a similar amount contributed by Dialight. A key aim of the project is to develop a solution that is very reliable but not prohibitively expensive.

Dr Roger Shuttleworth, from the Power Conversion Group at Manchester University, said: “LED technology first came to prominence in instrument displays in the 1970s, but we are increasingly seeing it used in things like traffic signals and car lights.

“Towards the end of the 20th century, the old-fashioned sodium street lights that made everything look orange were gradually replaced by high-pressure sodium lamps. While these are brighter and more aesthetically pleasing, and can help tackle street crime and anti-social behaviour, they are also less energy efficient.

“With the environment at the top of the public and political agenda, energy saving has become a very important issue. When you consider how many street lights there are in the UK alone, it is clear there are some big opportunities for energy and cost savings,” he added.

Dialight Lumidrives’ managing director Gordon Routledge studied electrical and electronic engineering at the University of Manchester Institute of Science & Technology (UMIST), graduating in 1996. He explained: “LEDs are on track to become a major source of lighting over the next decade. Although significant investment is on-going in the core development of the LEDs, the surrounding technology development is being left to manufacturers who have little knowledge of electronics or LEDs.

“We are proud to be working with the University of Manchester to develop technology which will drive the adoption of this revolutionary lighting source in everyday applications,” he added.

Although high-pressure sodium vapour street lighting - common across much of Europe - gives an efficiency of about 85 lumens per watt, he claimed that LED technology was already on track to exceed 150 lumens per watt and predicted this figure would rise further as new semiconductor developments occur.

As well as cutting energy consumption and overall running costs, researchers say that LED street lighting helps reduce light pollution; the sky glow that radiates from big cities could become a thing of the past. It is also proposed that LED street lighting could be controlled and dimmed when necessary.

Their longer lifespan means that LED street lights need to be replaced less often, reducing potential traffic disruption and council repair bills. The lifetime of the LED module that the collaborators are working on is in excess of 10 years in a road lighting application, some four times longer than a conventional street light.

Although LEDs do experience a gradual and permanent reduction in light output during their normal operating life - caused either by a reduction in the light-generating efficiency of the LED die, or a reduction of the optical path within the LED package - the Dialight street LEDs are expected to provide about 70 per cent of their original light output after 50,000 hours or 10 years, provided that they are not overdriven.

This is not as significant as it sounds because the human eye is relatively insensitive to changes in light output, and a reduction to about 50 per cent is necessary to create a noticeable change.

It is, says the company, easy to convert existing street lighting to an LED source because no electronics skills are required. It has been developing and exploiting LED technology for lighting applications for almost five years, with a successful produce range supplied to many of the world’s leading equipment manufacturers.

道路照明将率先使用低能耗的发光二极管照明技术

英文阅读资料:道路照明技术将采用低耗能技术

英文阅读资料:道路照明技术将采用低耗能技术

英国曼彻斯特大学和Dialight Lumidrives公司联合,使用发光二极管技术,研发更加耐用、低能耗的道路照明设备。图中所示为德国雷根斯堡市,彩色灯柱(不是顶端的白色灯)中就包含有Dialight公司的LED单元。

英国的一所大学的研究人员和一个发光二极管(LED)专门企业合作,期望能够开发出将LED技术优势利用在道路照明中的最佳方法。

LED最先于上世纪70年代出现在数字手表和计算机中。今天,这项技术取得了进步,可以用来制造耐用、低能耗且对社区友好型的道路照明设备。

其好处有:预期寿命长(可达100,000小时),根据型号大小以及能量消耗率逐渐增加高亮度输出,对于普通照明和指示灯来说,可以用LED来实际替代传统的钠蒸汽单元。而且,由于LED体积是如此之小,所以制造商用它来制造更加圆滑、体积更小、轻量级的发光体的可能性就大大增加了。

重要的是,LED对环境友好,而且还安全。它不含玻璃、灯丝或汞,所以不会发生由于卤素或高强度电流(HID)而导致灯具爆炸的情况。

同时,它成本低,也不会受到由于钠蒸汽单元而带来的汞处理限制。低压直电流操作可以完全保证消费者的安全。彩色的LED模块可以使颜色非常逼真,而且比白炽灯单元更具能源有效性。

LED照明专门公司Dialight Lumidrives的创立者是曼彻斯特大学校友,该公司最近和这所英格兰北部的大学开展了合作计划。来自大学电气与电子工程学院的研究人员正在利用他们的专业知识,研究如何使紧密压缩在一起的一组LED能够安全、可靠地工作。

用LED来提供照明解决方案的方式如果得到应用的话,可以使能源消耗量减少25-50%。但是当需要12,000流明(一只典型的60瓦家用照明是800流明)或以上的照明时,发热和其它与电相关的问题将成为采用LED技术的障碍。

曼彻斯特大学的工程师们将会和位于约克郡的Dialight Lumidrives公司一道,解决一些比较难攻克的问题,如紧密压缩在一起的一组LED所产生的热量。由于LED模块会被用在户外,所以需要考虑实际的环境因素,如关键的散热片上被鸟筑巢的可能性。

还有一项需要克服的困难就是规章问题。规章中规定了灯的刺眼程度和光污染限制;明确规定了LED光源可以安装的区域。这些都造成了严重的挑战。

这项为期一年的计划得到了来自英国政府175,000英镑的资助,Dialigh公司也提供了同等数量的资金。计划的一个主要目标就是,开发出一种十分可靠而低廉的解决方案。

曼彻斯特大学电能转换部(Power Conversion Group)的Roger Shuttleworth博士说:“发光二极管技术首次显示出其卓越性是在上世纪70年代的器具显示上,随后我们越来越多地看到发光二极管被用在诸如交通信号灯和汽车灯这样的事物上。”

“到20世纪时,让所有东西看起来都呈桔色的老式钠路灯逐渐被高压钠灯所取代。这些高压钠灯发光更明亮,而且符合视觉审美,还能帮助解决街头犯罪和反社会行为,同时耗能低。”

他又补充说:“随着环境问题被提到了国家和政府日程的首要位置,节省能源成了一个重要的问题。如果你能想想光英国就有多少路灯,那么你就会清楚在能源和费用节省上存在着多大的机会。”

Dialight Lumidrives公司总经理曾在曼彻斯特大学科技学院学习电气和电子工程,1996年毕业。他解释说:“未来10年,发光二极管要成为主要的照明来源,现在正在朝这个方向前进。虽然大量的资金正在注入发光二极管的核心研究中,但是,由于没有什么电子学或发光二极管知识,制造商们忽略了相关技术的同步开发。”

他接着说:“能和曼彻斯特大学合作开发这项技术,我们感到很骄傲。技术开发成功后,这个具有革命性的光源就可以进行日常使用了。”

虽然在欧洲非常普遍的高压钠蒸汽路灯每消耗一瓦电,可以产生85流明的照明量,但是他认为LED技术已经能使每瓦电产生的流明量超过了150,而且随着新半导体的出现发展,预计这个数字还要更高。

研究人员表明,在降低能源消耗以及整体操作成本的同时, LED路灯还有助于减少光污染,大城市向天空排放热量的时代可能就要成为过去了。还有建议说,LED路灯应该可以根据需要来调节亮度。

LED路灯的长寿命意味着不需要经常进行更换,从而减少了交通中断的潜在性,降低了政府为此而支付的维修费用。双方正在合作研究的路灯LED模块寿命超过了10年,是普通路灯寿命的四倍多。

在正常操作下,LED必需要经历光输出逐渐减少的过程,而这个过程是会一直持续着的。导致光输出减少的原因可能是由于LED产生光的效率在降低,或者是由于LED压缩包内的光径在减少。不过,只要没有超负荷使用,Dialigh的 LED路灯在工作50,000小时或10年后,还可以达到70%原始光输出的能力。

这并不像听起来那样重要,因为相对来说,人类的眼睛对光输出的变化并不是很敏感,只有减少量达到50%的时候才会有明显的感觉。

该公司表示,将现有的路灯换成LED的路灯应该很简单,因为不需要任何的电子学技术。在照明方面,公司已经进行了五年的LED技术开发和使用,拥有一系列的产品,成功地供应着许多世界著名的设备制造商。

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