"RicodJour" wrote in message
...
On Oct 18, 10:31 pm, wrote:
On Mon, 18 Oct 2010 18:22:48 -0400, "Robert Green"



wrote:
"Stormin Mormon" wrote in message
...
I have thought about it. If you'd like me to change my mind, please
supply some proof. Just saying someone is wrong, is useless. Telling
someone to "think about it" is insulting.

Our friend is using word games and appears to be claiming that somewhere
off
camera, in a perfectly sealed box, in a perfectly theoretical world where
all energy radiators are perfect and there's no such thing as conversion
efficiency, all light and heat end up the same - as heat. He's claiming
the
difference between the ratio of heat/light emitted does not matter
because
the CFL's much greater light output would be converted back into heat
when
it strikes the sides of the hypothetically perfect box.

The quote, precisely, was: "Nonsense. A 100W incandescent bulb will put
out
exactly the same heat as a
100W fluorescent; 100W."

"Exactly the same" is a) true only in the most theoretical sense, b) true
only if you decide to use the words heat and light interchangeably and c)
perhaps not really true even then. What he may have meant is "eventually"
but "exactly" implies that they *emit* the same amount of heat
simultaneously. That's simply not true. While both may radiate 25 watts
of
energy, they do it in very different forms.

In the much more rational and problematic world we live in, the CFL not
only
puts out less heat when measured at the emitter, it will put out less
heat
overall. In the real world all conversions from one form of energy to
another involve losses of some kind. If that wasn't so, we would have
totally safe CFL furnaces, converting light into heat without pesky
direct
combustion of fuel or dangerous resistance heaters. That's as ridiculous
as
claiming that going from electricity to light to heat is as efficient as
going straight from electricity to heat without an intermediate process.

The device that puts out more heat to begin with will put out more heat
in
the final analysis because it will not experience any loss in the
reconversion of light to heat. "Exactly" would only be true in a weird
sort
of Flatland, where CFL bulb heat would be the least of one's problems. In
the real world, a tungsten incandescent bulb outputs more heat than a CFL
bulb of the exact same wattage, even when used as a heater.

CFLs put out more visible light than incandescents do for the same input
current and they do it by converting more of the input energy into
visible
light and not IR or radiated thermal energy. Any claim that the heat
ouput
is equal can be easily sanity checked by looking the difference in light
output for the same wattage.

The device that doesn't have to convert twice - once from electricity to
light and then from light to heat HAS to be the more efficient one,
making
statements that they are both equally efficient radiators of heat dubious
at
best. If the claim is true, it's only true in a theoretical sense and
applies to a world where no one actually lives. In the real world, CFL's
emit far more light than heat, and IIRC it's on the order of 60 lumens
per
watt compared to an incandescent's 15. IIRC, the CFL emits 30 BTUs for a
similar incandescent's 80.

LED 3.4 btu's/hour
Incand. 85.0 btu's/hour
CFL 30.0 btu's/hour

Source:http://www.designrecycleinc.com/led%20comp%20chart.html

Less light = more heat - over twice as hot according to these figures.

So yes, if you want to be a clever lad with words and use the terms heat
and
light interchangeably (except when you choose not to) AND you live in a
perfect theoretical world where conversion efficiencies are 100%, then
you
can say that CFLs and incandescents both output the same amount of heat -
eventually. It's a good reminder that one needs to watch for "magical
thinking" and "creative expression" on Usenet every damn day.

The only question is:
In the inefficiency of converting light energy to heat, what form does
the lost energy take???
If you can answer that one you aare all set.

My answer that it was very close to the same between the two types ,
rather than saying it was identical, is because I admit there is a
possibilty that a very small amount of the energy emitted by the bulb
might turn into something other than heat and light - and that the
light might not all return to heat - I'm not a Physicist.
Stormy says 100%. Not sure he's a phyisicist either.

You say there is an appreciable difference. You and stormy are both
adament that you are right and the other is wrong. Are you a
physicist? Can you explain where the energy that does not become heat
goes? If you can't, I'll have to lean to agreeing with Stormy -
because the FACT is energy cannot be destroyed. It is just converted,
at 100% efficiency, into another form of energy.

Well, now we're well into the how-many-angels-can-dance-on-the-head-of-
a-pin territory. While you're asking for the calcs, make sure that
they differentiate between heat from conduction, convection and
radiation, allow for differing emissivities, and, while we're at it,
can we nail down what dark matter is? Thanks!

Here's a thought - why don't you cross-post this to a physics
newsgroup and a couple of engineering ones? That should be
entertaining.

As you imply, the discussion at that level is largely irrelevant to the
concerns of AHR which is why I took exception to the purely theoretical
feldercarb about them being exactly efficient radiators of heat and light.

Things to ponder:

If energy is neither created nor destroyed, then where did the energy from
the Big Bang come from?

Why is the way the universe is expanding not quite matching up with the
theories, aka Dark Matter, Darth Vader's second cousin on his father's side.

Why doesn't a light bulb last forever? Are there processes other than the
generation of light absorbing energy?

Could the energy entering it be expended in not just heat but in physical
changes to the components?

Physicists have already created matter from energy so the rules get very
fuzzy the more theoretical you get:

http://van.physics.illinois.edu/qa/listing.php?id=1363

Why do things yellow and turn brittle under very bright light? Could that
energy be converted not just into heat but into chemical changes of the
material it strikes?

How do plants create biomass from sunlight?

Don't CFLs create RFI which will pass right through the box?

What would happen if you lowered (inside a waterproof container, for all you
wiseguys!) a tungsten bulb and a CFL of equal wattage into two calorimeters?
Would they both raise the temperature of the water an equal amount? All
interesting questions - for a theoretical physics group.

As you point out, if I came to AHR to read about angelic pin dancing it
would have been a far more entertaining discussion, but as it was written is
was wrong. At least if you believe in the common usage of the words "put
out, exactly, heat and light" He meant "eventually" - a word that has a
pretty clear meaning which isn't exactly "exactly." (-"

--
Bobby G.