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[report整理] SENEWS-2011-04-25

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[Homework]SENEWS-2011-04-25

This is the VOA Special English Technology Report.
Solar water heaters are used around the world and are not very difficult to build. The system we are going to describe is based on the design developed some years ago in Afghanistan.Since then it has been built and used in many countries.
It can heat seventy liters of water to sixty degrees sources.It can do this between sunrise and noon on the clear day with an average air temperature of thirty two degrees sources.
There are two parts of the solar water heater.One part is made of the sheet of metal painted  black.Black surfaces become hotter in the sun than surfaces painted any other color.This black metal plate is called  a collector.The collector  is placed in contact with the water.
There are several kinds of metal sheets that can be used for the collector.Corrugated metal will work very well.C* sheets are often used as roofs on housing.Once the water is heated,it is keeped hot with insolation material.This allows the water to stay warm for a long time.
The second parts of the solar water heater holds the water for the system.This storage tank can be a container that holds about 100 liters.Two wrapper pipes are attach to the water storage tank.
One pipe lets water flow into the system,the other lets water flow out.When the water heater is working correctly,water will flow from the storage tank to the collector and back again.
You can use the hot water at the top of  the tank for washing and cleaning.You can change the flow of water so that the temperature is hot or warm as desired.
This solar water heater is easy to build and operate.It will last about two years before the wrapper pipes need to be replaced.
There was also something else will to need to make the solar water heater work --the sun.As you might imagine the heater will heat water only on sunny days.
You can get more information about solar water heaters and other project from inter* workers  vita.This group works internationally to fight poverty.The website is interpriseworkers.org. Choose the link for news in resources then click on pubulications.
And that's the VOA Special English Technology Report.Tell us if you have ever build the solar water heater or have ideas for improvements.Post your comments at voaspecialenglish.com.Where you can also found transcripts mp3s and podcasts about our programs .We also offer english teaching activities in the classroom section of our website.I'm Steve Ember.

This post was generated by put listening repetition system,  Check the original dictation thread!
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