Total Pageviews

Thursday, November 4, 2010

Vacuum Tube Water Heater

EVACUATED SOALR TUBE WATER HEATERS

Solar evacuated tubes AKA solar vacuum tubes are pyrex (borosilicate) glass that does not crack or break when exposed to radical temperature changes. This glass is crystal clear, very strong and have been used for years in China. Evacuated tubes offer an inexpensive method for efficiently transferring the sun's power to heat water. These tubes have a clear outer layer with a dark inner absorber layer (selective coating) containing a vacuum between the glass walls.


Just like the internal double glass walls of a traditional glass thermos, the vacuum (lacking air molecules) in the solar tubes prevents heat from escaping into the atmosphere. Unlike z glass thermos, solar tubes are clear and not mirrored allowing sunlight can penetrate the first layer with a 90%+ efficiency as sunlight is absorbed on the dark inner layer.




The entire unit requires the tubes to be exposed to pressurized water in a traditional setup. Because the glass cannot withstand pressure exceeding 20 PSI, these heaters incorporate a copper spiraled core that is placed inside the length of the tube connected to a nipple (heat pipe condenser). Only this copper nipple, which gets very hot, is exposed to water pressure. These copper nipples can withstand several hundred PSI. This setup of heat transfer reduces the units overall efficiency.

For the backyard scientist, the copper core is not needed. By filling these tubes with water and setting them out in the sun, water boils with no additional Reflectitve Film, Fresnel Lens, or Parabolic Mirror in about an hour. Adding any of the above increases boiling times dramatically.

Our video with a Parabolic trough "Solar Water Heater Steam Parabolic Mirror Trough"I used a black steel pipe as the absorber. Light refracted can be seen throughout the video due to heat loss into the atmosphere dramatically reducing efficiency. Touching this pipe with your hand would be an instant mistake! By replacing the black pipe with a solar vacuum tube in the same design, the outer glass tube would be warm to the touch "Solar Water Heater Steam Parabolic Mirror Trough".

Solar tubes come in a variety of lengths and diameters. They are a great tools for the solar backyard scientist and are used in many professional jumbo scale installations. The concept can boost efficiency of your project by 50% saving you time, money and unit footprint dimensions. These tubes are also a great teaching tool for science teachers.

One thing to remember; NEVER leave these tubes in the path of a Fresnel Lens, Parabolic Reflector or in the sun EMPTY. The tubes can build extreme heat exceeding the tolerance of the black coating and adding water to a 300c tube will shock even the best borosilicate glass.





Dan Rojas
Greenpowerscience.com

11 comments:

  1. Hi there Dan and Denise.

    I do hope you are both well and happy.?
    Also hope you both had a Great Christmas
    and New Year.

    I do enjoy your Videos and write-ups...
    You are an Attractive and pleasant Young
    couple, and it comes across in your work.

    We don't seem to have anyone over here
    in England doing anything like this.

    While reading your write-up and watching
    the Video, my thoughts went to, Distance
    from the Mirror to the collector...???

    Is there a set distance, or, is there
    a formula that I need to use to work
    it out.?

    Thanks for all Your Work...

    Please Continue.

    Loopy Lou

    ReplyDelete
  2. Dear Mr. Dan Rojas,
    I want to contact you by E-mail, could you kindly give me your E-mail address?

    Regards,
    Mahshid Yousefian
    mahshid.yousefian@gmail.com

    ReplyDelete
  3. Yes vacuum tubes are very powerful

    Hope one day they will power a commercially produced sterling generator to provide electric for domestic use !

    Cheers tony cssolar Spain

    ReplyDelete
  4. Hi. your article fanttastic. thanks in informahie.....

    :Solar Water Heaters

    ReplyDelete
  5. I also mist the glass and stick bubblewrap to it for the insulation it provides, and can still get a 13 degree rise in temp. glendora plumbing

    ReplyDelete

  6. solar water heater system do not pollute. By investing in one, you will be avoiding carbon dioxide, nitrogen oxides, sulfur dioxide, and the other air pollution and wastes created when your utility generates power or you burn fuel to heat your household water.

    ReplyDelete
  7. Good web site! I really love how it is easy on my eyes and the data are well written. I am wondering how I could be notified when a new post has been made. I’ve subscribed to your RSS feed which must do the trick! Have a great day!

    Solar water heater

    ReplyDelete
  8. I loved as much as you’ll receive performed right here. The caricature is attractive, your authored material stylish. nevertheless, you command get bought an nervousness over that you want be turning in the following.
    solar water heater systems

    ReplyDelete
  9. Alternative energy refers to energy sources which are not based on the burning of fossil fuels or the splitting of atoms. λεβητες πέλλετ

    ReplyDelete
  10. Hi ,Really interesting article about EVACUATED SOALR TUBE WATER HEATERS,learn a lot !
    For more great quality informations about Alternative Energy visit my page:http://isparktube.com/
    Regards

    ReplyDelete
  11. I would like to thank you for the efforts you have made in writing this article.
    Click here

    ReplyDelete