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OT free lighting
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"David Hill" wrote in message ... Interesting item, can you find a use for it? http://www.di-ve.com/news/invention-lights-world Not exactly a 'lamp' though is it? It just reflects the sunlight through a hole in the roof. After sunset you're in the dark. Google for 'sun pipe' to see a more hi-tech version of the same thing. R. |
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On Wed, 14 Aug 2013 12:15:46 +0100, "Ragnar"
wrote: "David Hill" wrote in message ... Interesting item, can you find a use for it? http://www.di-ve.com/news/invention-lights-world Not exactly a 'lamp' though is it? It just reflects the sunlight through a hole in the roof. After sunset you're in the dark. Google for 'sun pipe' to see a more hi-tech version of the same thing. R. Making holes in the roof sounds a bit risky! Pam in Bristol |
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"David Hill" wrote in message ... Interesting item, can you find a use for it? http://www.di-ve.com/news/invention-lights-world I wonder if the price of bleach will now rocket. Bill |
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"David Hill" wrote in message ... Interesting item, can you find a use for it? http://www.di-ve.com/news/invention-lights-world Not exactly a 'lamp' though is it? It just reflects the sunlight through a hole in the roof. After sunset you're in the dark. Google for 'sun pipe' to see a more hi-tech version of the same thing. R. I first saw them being used in Lesotho several years ago. Mostly made from 2ltr pop bottles they are amazingly effective. Mike |
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On 14/08/2013 09:25, David Hill wrote:
Interesting item, can you find a use for it? http://www.di-ve.com/news/invention-lights-world Probably only for an hour or two around midday, and only on the equator. To get 40 - 60 watts equivalent (let's say 50 for simplicity), with the sun directly overhead, you'd need a bottle with a diameter of about 25 cm. I guess that a water bottle for a dispenser wouldn't be far off that, so it is feasible. But it would be heavy (around 20 kg), and a flat piece of glass with the same diameter would do just about the same thing. -- Jeff |
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On Wed, 14 Aug 2013 12:15:46 +0100, Ragnar wrote:
http://www.di-ve.com/news/invention-lights-world Not exactly a 'lamp' though is it? It just reflects the sunlight through a hole in the roof. Refracts BWTH. B-) After sunset you're in the dark. This is true, I wonder whay they don't build their shacks with windows? I guess they are so packed together that light doesn't penetrate to the sides very much. -- Cheers Dave. |
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"Bill Grey" wrote: "David Hill" wrote: Interesting item, can you find a use for it? http://www.di-ve.com/news/invention-lights-world I wonder if the price of bleach will now rocket. Well at least now we know where all the recycled plastic bottles go. -- Sue |
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On 14/08/2013 14:08, Dave Liquorice wrote:
On Wed, 14 Aug 2013 12:15:46 +0100, Ragnar wrote: http://www.di-ve.com/news/invention-lights-world Not exactly a 'lamp' though is it? It just reflects the sunlight through a hole in the roof. Refracts BWTH. B-) After sunset you're in the dark. This is true, I wonder whay they don't build their shacks with windows? I guess they are so packed together that light doesn't penetrate to the sides very much. the cost and availability of glass? |
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On 14/08/2013 14:04, Jeff Layman wrote:
On 14/08/2013 09:25, David Hill wrote: Interesting item, can you find a use for it? http://www.di-ve.com/news/invention-lights-world Probably only for an hour or two around midday, and only on the equator. To get 40 - 60 watts equivalent (let's say 50 for simplicity), with the sun directly overhead, you'd need a bottle with a diameter of about 25 cm. I guess that a water bottle for a dispenser wouldn't be far off that, so it is feasible. But it would be heavy (around 20 kg), and a flat piece of glass with the same diameter would do just about the same thing. I think you need to look again at the weight. A full 2 litre pop bottle weighs 2 kg + the weight of the bottle, and this is the size used. |
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On 14/08/2013 17:59, Chris Hogg wrote:
A calculation: sunlight's composition at ground level, per square meter, with the sun at the zenith, is about 527 watts of infrared radiation, 445 watts of visible light, and 32 watts of ultraviolet radiation (from http://en.wikipedia.org/wiki/Sunlight). Call it 450 w/m^2 of visible light, or 0.045 w/cm^2, or 22.2 cm^2/w. If a bottle delivers say 50 watts of light, then each bottle will have to have a cross-sectional area of 50/0.045 = 1110 cm^2, or a diameter of about 37.6 cm. So they'd have to be even bigger than Jeff suggested, which makes me think the estimate of 40-60 watts is somewhat exaggerated. Yes, I was mistakenly basing my calculation on the approx 1000w/m^2 of total solar energy delivered perpendicularly. I hadn't taken into account that only around half is visible. I had also assumed that when the term "water bottle" was used in the article, it was referring to those large bottles found on water coolers. -- Jeff |
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On 14/08/2013 19:41, Jeff Layman wrote:
On 14/08/2013 17:59, Chris Hogg wrote: A calculation: sunlight's composition at ground level, per square meter, with the sun at the zenith, is about 527 watts of infrared radiation, 445 watts of visible light, and 32 watts of ultraviolet radiation (from http://en.wikipedia.org/wiki/Sunlight). Call it 450 w/m^2 of visible light, or 0.045 w/cm^2, or 22.2 cm^2/w. If a bottle delivers say 50 watts of light, then each bottle will have to have a cross-sectional area of 50/0.045 = 1110 cm^2, or a diameter of about 37.6 cm. So they'd have to be even bigger than Jeff suggested, which makes me think the estimate of 40-60 watts is somewhat exaggerated. Yes, I was mistakenly basing my calculation on the approx 1000w/m^2 of total solar energy delivered perpendicularly. I hadn't taken into account that only around half is visible. I had also assumed that when the term "water bottle" was used in the article, it was referring to those large bottles found on water coolers. Well the article does show pictures including how they are set and what the bottles are. |
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On Wed, 14 Aug 2013 17:59:31 +0100, Chris Hogg wrote:
If a bottle delivers say 50 watts of light, then each bottle will have to have a cross-sectional area of 50/0.045 = 1110 cm^2, or a diameter of about 37.6 cm. So they'd have to be even bigger than Jeff suggested, which makes me think the estimate of 40-60 watts is somewhat exaggerated. I think you are missing an efficiency factor. I suspect the light you get from the pop bottle is similar in level to that which you get from a 40-60 watt tungsten incandescent bulb. Incandescent light bulbs are horribly inefficient, less than 5%. Reversing the calculation, a 2 litre pop bottle has a diameter of about 9.5 cm, so a cross sectional area of about 71 cm^2, and would give a visible light output of 71x0.045 = 3.2 watts. 3.2 Watts of real light or 64 Watts of incandescent assuming 5% efficiency. Most incandescent bulbs won't be that efficient... -- Cheers Dave. |
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On Wed, 14 Aug 2013 15:08:47 +0100, David Hill wrote:
I wonder whay they don't build their shacks with windows? I guess they are so packed together that light doesn't penetrate to the sides very much. the cost and availability of glass? Why do you need glass? Clear or translucent plastic sheet or opened out bag would do. Opaque one for a curtain. -- Cheers Dave. |
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"Indigo" wrote in message ... "Bill Grey" wrote: "David Hill" wrote: Interesting item, can you find a use for it? http://www.di-ve.com/news/invention-lights-world I wonder if the price of bleach will now rocket. Well at least now we know where all the recycled plastic bottles go. -- Sue As a matter of interest, They are processed and made into Fleece jackets and such like. All clever stuff ! Bill |
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