Re: Fluorescent heating

On Mon, 29 Dec 2008 00:59:33 -0800, JosephKK <quiettechblue@xxxxxxxxx>
wrote:

A flourescent light is pretty much the same. They consume less power, dissapate less heat, but still most of the energy consumed
is dissapated in the form of heat. It doesn't take very much energy to radiate light - we just can't do it efficiently.
Incandescent is horribly inefficient - but it's cheap and we don't care that we are wasting so much energy. Flourescent lights
take a circuituous route to emit light in the visible spectrum - not very efficient at all, but much better then incadescent.

LEDs are much more efficient, but still some of the energy goes to heat - I'm not sure what the ratio is. Visible light itself is
not very much energy. It all goes to heat.

I wonder whether LED's are more efficient than the good old
tube fluorescent lamps.

Not yet.

Some white LEDs are pushing 160 lumen/watt now - at least if you believe
Cree's press releases (they claimed 130 lumen/watt about 2 years ago).

http://news.moneycentral.msn.com/ticker/article.aspx?Feed=PZ&Date=20081119&ID=9391712&Symbol=US:CREE

LEDs capable of 90+ lumens/watt are starting to appear in consumer LED
lighting some of the claims made are a bit optimistic eg

http://www.arraylighting.com/Story/index.html

But there are very few fluorescents that can work as efficiently as that.

My gut feeling is they still have some distance to go to get there.

Yes.

Consumer mass produced ones still lag a bit behind the best prototypes.
Although for some coloured light sources like traffic lights and
indicators LEDs can still come out ahead.

In answer to the original question a low pressure sodium lamp with the
InO coating etched off the glass envelope would emit a pretty strong IR
line source at very high efficiency (with a suitable low pass filter to
stop the obvious visible yellow sodium D line escaping).


High Lumen/watt is not all we need.
The color temperature (Kelvin) and Color Rendering Index (CRI)
are very important factors.
Today I can't buy LEDs that have better efficiency than
fluorescents with 2700K and >CRI90 for my home lighting.


You cannot buy fluorescent with a color temperature of 2700 K
or a CRI 80 either. Nobody makes them.

Yes I could here in Sweden.
My favorite tubes are 2700K and CRI95.
Here you can see one of them. I have 4 of them.
Using them every night.
http://tekniken.se/misc/philips_tld36w-92.jpg
http://tekniken.se/misc/philips_tld.png

.

Relevant Pages

  • Re: Fluorescent heating
    ... Incandescent is horribly inefficient - but it's cheap and we don't care that we are wasting so much energy. ... LEDs are much more efficient, but still some of the energy goes to heat - I'm not sure what the ratio is. ... You cannot buy fluorescent with a color temperature of 2700 K or a CRI ...
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  • Re: Fluorescent heating
    ... is dissapated in the form of heat. ... It doesn't take very much energy ... Some white LEDs are pushing 160 lumen/watt now - at least if you believe ... Consumer mass produced ones still lag a bit behind the best prototypes. ...
    (sci.electronics.design)
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