Just moozing

Before you can check your notes, you must make them…

Solar heat device – a prototype

with 2 comments

I have some buildings at home, that I want to heat a bit, so I have been looking into solar air heating. It is something people do, and I decided to test the version using aluminium cans, like this one.

The idea

We did a prototype to see how well the design is. On the page mentioned above he get 2kW of warm air from his 2.3 m2 solar heater. It sounds impressive and it is all made of wood, plexi glass and aluminium cans painted black. It is well within my carpentry capabilities.

The other part is that we want something to measure for the initial MSP430 project. So data logging 2-3 temperature sensor and whatever other sensors we fancy, is a good startup project. It will require I2C up and running and the ability to extract data from the device – simple, basic and very useful,

Building the device

We were two people working 1-1½ days to build it. It would have been faster, if we had the proper tools. It was ok, and I expect that building a version twice as big, would require more or less the same amount of work.

Bill of materials

  • Some plywood board for the back plane. We used something I had in stock of around 20 mm thickness.
  • Some wooden boards for the sides. I had some old floor boards in stock. It turned out to be a good thing, since the tongue of the board was very suited as end limit for the glass plate.
  • A glass plate approximately 50x60cm. We have that in stock from an old green house.
  • 35 ordinary 330 ml aluminium cans. We had that in stock also…
  • Black spray can. We bough that one as cheap as possible.
  • Thick cardboard used for back plane insulation. We had that also.
  • Screws, sealant and probably some more minor things.

We did not spend €10 on this project.

Testing

I don’t know how to test it. It is snowing and we don’t have much sun these days.

What we did test was using 2×150 W + 1×400 W spots to simulate the sun, and we raised the temperature from a room temperature of 4 degress celcius to an outgoing flow at 18 degrees. So something is working. The flow was almost non-existent, and I am working on how to measure pressure or the air flow to get an idea of the efficiency of the system.

I also want a sensor that tells me how much the sun is shining on the device, but that is for modelling of the system – which is kind of irrelevant from a user point of view compared to the actual energy throughput.

Improvements?

Yes, this is a prototype and it could be improved.

  • For the top manifold, I think that to cut something in styrofoam would be cheap, simple and a good way to make the top chamber airtight.
  • Better isolation.
  • Improved holes. It is my impression that you have a flow vs. temperature rise trade-off, and that the key is how long you keep the air in each can. I will probably have a more informed opinion on this when I do the calculations on the thermodynamics of the system.
  • High isolating glazing. That comes highly recommended and it should be doable – just not with stick glass 🙂
  • Sealant and paint considerations. I read that the cans could become very hot – as in 200-300 degrees celsius. It is relevant when deciding what paint and sealant/adhesive to use.
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Written by moozing

January 29, 2013 at 09:00

Posted in Tech

Tagged with , ,

2 Responses

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  1. Whats up are using WordPress for your blog platform?
    I’m new to the blog world but I’m trying to get started and create my own.
    Do you need any coding expertise to make your own blog?

    Any help would be greatly appreciated!

    Donny

    May 7, 2013 at 11:46

    • (this seems to be off topic…)

      Anyway, wordpress works for me, and I am just doing the default installation. The guides on wordpress.com are good also.

      moozing

      May 7, 2013 at 12:52


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