介绍： 版权归原作所有，仅供此学习，若有侵权请告知删除。
[11:49.26]The last reading.
[11:52.20]The Solar Water Heater
[11:55.15]Solar water heaters are used around the world and are not very difficult to build.
[12:02.37]The system is based on a design developed some years ago.
[12:06.84]It can heat seventy liters of...

介绍： 版权归原作所有，仅供此学习，若有侵权请告知删除。
[11:49.26]The last reading.
[11:52.20]The Solar Water Heater
[11:55.15]Solar water heaters are used around the world and are not very difficult to build.
[12:02.37]The system is based on a design developed some years ago.
[12:06.84]It can heat seventy liters of water to sixty degrees Celsius.
[12:12.28]It can do this between sunrise and noon on a clear day
[12:16.79]with an average air temperature of thirty-two degrees Celsius.
[12:21.75]There are two parts to the solar water heater.
[12:25.56]One part is made of a sheet of metal painted black.
[12:30.79]Black surfaces become hotter in the sun than surfaces painted any other color.
[12:37.54]The second part of the solar water heater holds the water for the system.
[12:42.67]This storage tank can be a container that holds about one hundred liters.
[12:48.10]Two rubber pipes are attached to the water storage tank.
[12:53.54]One pipe lets water flow into the system.
[12:57.23]The other lets water flow out.
[13:00.39]The solar water heater will last about two years
[13:05.01]before the rubber pipes need to be replaced.