Fluorescent heating

What would be the point? An incandescent heat lamp is far simpler and 100% efficient.

I can't see the use unless a narrow band of infrared is needed for a specific application.

--Damon

Probasbly, buy why?

Thanks, Rich

Is that an example of slurred spelling?

Easy. Paint the tube black.

John

In incandescence, a lot of the energy is lost as conductive heat -- as opposed to radiative heat. In fluorescence, most of the energy goes into EM radiation. That's fluorescence is better.

An incandescent lamp has to get hot emit IR. A fluorescence lamp, OTOH, can directly convert majority of the power into IR radiation [or whatever EM radiation wavelengths the materials flouresce at].

The narrowband IR has applications, as I described in the original post -- basking and broiling.

The reason I chose that "middle" zone of IR-C [described in the original post] is because it is safest for the eyes. IR-B and IR-A can harm the lens. IR-A is especially hazardous to the retina.

The short-wave end of IR-C starts to resemble IR-B. The long-wave end of IR-C gets similar to microwaves. I want neither so I chose the "second" zone, as described in the 1st post of this thread.

The 'Radium' troll is back with another new screen name.

--

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There are two kinds of people on this earth: The crazy, and the insane. The first sign of insanity is denying that you're crazy.

Ok, "The MAJORITY" of the power. Stop and ponder that.

An incandescent lamp (of any type) converts _ALL_ of the power into heat,light is just a nice side-benefit. and even the light gets turned back into heat,at some point.)

So does a fluorescent light. ;-)

--
Keith

No, just typing too fast and neglecting to proofread.

I won't be slurring for another couple of hours. ;-)

I hereby accept my 40 lashes with a wet noodle. ;-)

Thanks, Rich

A piece of nichrome turns the power into IR radiation; as to whether cherry-red counts as "incandescent" is a question best left to the dictionary writers. ;-)

Hope This Helps! Rich

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.

Go put your hand on a standard 40w flourescent tube. It's warm. Put your hand (carefully!) on/near the ballast. It's quite warm also. That is where most of the 40w is going.

Better issue for a physics group, but there must be a limit to the frequency down-conversion ratio for fluorescence. Assuming an ionized gas source, near-UV, and a thermal IR output, you'd need a down-conversion ratio of roughly 50:1 to get to thermal wavelengths. If an electron absorbs a UV photon, it would have to decay to its ground state by about 50 approximately-equal quantum jumps. That's just not going to happen. Efficiency would be pitiful, and most of the UV would be converted to heat.

At a quantum efficiency of 10%, the overall conversion efficiency would be 1/500, or 0.2%.

A filament in an evacuated tube would be a lot better.

A little science can be helpful in evaluating novel ideas.

John

It may be better to use infrared LEDs (in fact, CFLs will probably be replaced with LEDs for lighting, eventually, but there is considerable political and economic investment in CFLs that will create resistance). Here is a link for some 940 nM LEDs that put out 500 mW each for about $0.50 a pop.

A few more here, but none over 940 nM:

Here's an LED infrared medical device:

Some other links:

I don't know if there is any technical reason for not having LEDs in the wavelengths you are seeking, but I'm not sure it really matters much for heating. The important thing is for the radiant energy to be directed to the object that needs to be heated, rather than elsewhere, for maximnum efficiency. A heater is only 100% efficient if you really want the heat everywhere.

Paul

Then one day the light goes on in some one's head, and figures out after all the years of science and technology base on theories we currently believe in, as fact, is turn upside down and explained away, in a totally different way that actually make sense to present knowledge and fills in the gaps in those gray area's that couldn't be explained, to be proven away like so many theories are today.

Power sources as small as watch batteries run's your house whole for a year or more and cost very little, if nothing to replenish. No more buying energy for your vehicle, it'll be self renewable. Space travel will be nothing more than like taking a trip to the next state. etc.

The new physics will be presented to the young and they will prosper in technologies based on the new physics in ways unimaginable.

How ever, there will still be people wanted to live away from this up raise of knowledge and live style to filter them self's from this new world of high tech and remain intact with nature. Mean while, others will be taking advantage of this new understanding of knowledge because it's not so intimidating them any more until one day, some girl wakes up on the wrong side of the bed with PMS, decides to trigger off a dooms day boom she built the night before while watching her favorite show in 4D.

All major area's of technology get destroyed, all people with in those area's also parish. Those that are left behind are those up in the hills that wanted to get away from the technology and start a new society. They rewrite their own bible trying to explain the history of their demise, not knowing the advance technology well enough and thus not being able to record it other than a story that ends up as the new twisted history book called the Bible. After being past down through generates getting rewritten and altered to suite the needs of leaders so that their followers can be led like sheep!.

And so, we rewrap up to where we are now! :)

Happy Xmas

"

Most fluorescent lamps optimized for producing visble light are only around 20-30% efficient at producing visible light. Longer wavelengths would have less efficiency due to Stokes Loss being greater. Furthermore, "low temperature thermal IR" has a low rate of passing through even 1 mm of glass.

Excluding ones optimized for production of UV (and similar low pressure mercury vapor lamps lacking phosphors for production of UVC), such lamps have fair efficiency at producing convected/conducted heat.

Lamps that get hotter than those are good at producing radiant heat. Keep in mind that except for heat punps, nothing exceeds 100% efficiency at conversion of electrical energy to heat, and quite a few incandescent lamps and glowing resistive heat elements are great at converting electrical energy to infrared.

Infrared best perceived by human bodies as materializing as heat upon impact upon skin is at wavelengths near and over 1.5 micrometers. "Quartz heaters" and suitable "glow coils" do well at that, despite having efficiency of producing visible light exceeding zero and efficiency at producing infrared of wavelengths shorter than 1.4 micrometers of a few percent, along with a bit of heat convected/conducted from the source rather than radiated.

Keep in mind that 4-foot fluorescents are designed to have most of their more-exposed surface at temperature close to 40 degrees C (313 K), and are

30% or less efficient at producing radiation other than thermal IR - the remainder is thermal IR, or convected/conducted heat. And they are designed to do such in a 25 C (298 K) ambient - and a 313 K source in a 298 K ambient receives 82% as much thermal IR as it produces (4th power law for thermal radiation). Looks like most of their heat output is not thermal IR.

Changing them to have phosphors producing longer wavelength IR helps little. If the phosphor produces 1.6 um from excitation by .254 um that is produced initially at 60% efficiency (other 40% becoming non-radiant heat at that stage), Stokes Loss says that .254/1.6 (15.9%) of the 60% - combining to 9.54% - would be efficiency of non-thermally-producing such human-skin-absorbed IR, should the phosphor have quantum efficiency of 100%. In addition to the thermal IR otherwise produced at maybe 20% efficiency - with the remaining heat being convected/conducted. It appears to me that incandescent resistive heating devices glowing some or another orangish color do a lot better!

- Don Klipstein ( snipped-for-privacy@misty.com)

You're assuming IR and heat are the exact same thing. They aren't. IR is only heat, when that heat is radiant heat. Non-radiant heat is not IR at all.

dissapate less heat, but still most of the energy consumed

light - we just can't do it efficiently.

we are wasting so much energy. Flourescent lights

efficient at all, but much better then incadescent.

not sure what the ratio is. Visible light itself is

I wonder whether LED's are more efficient than the good old tube fluorescent lamps. My gut feeling is they still have some distance to go to get there.

M

Santa knows if you've been bad..........