Hi.
I've just read this : http://en.wikipedia.org/wiki/Power_%28physics%29
but i don't understand how i would calculate say, if my 1kW heater was on for 3 minutes, how many watts would it have used ?
Thanks,
Gary.
Quote from: DeepCut on December 03, 2010, 11:39:43 PM
Hi.
I've just read this : http://en.wikipedia.org/wiki/Power_%28physics%29
but i don't understand how i would calculate say, if my 1kW heater was on for 3 minutes, how many watts would it have used ?
Thanks,
Gary.
watts is a unit of power, the rate energy is used. a thousand watts is a thousand for one second or 1000 hours.
energy is the power times the time it is used.
3 minutes times 1000 watts is 3000 watt minutes or one twentieth of a kilowatt hour.
fritznien
Deep,
power ( watts ) is a measure of joules burned (energy ) per second, much like speed is a measured of miles covered for hour...
so, your 1KW heater left on for 3 minutes would consume...
P := 1KW x 180(seconds) ..
:= 1000 x 180 = 180,000 joules of energy used.
Thanks both of you that's totally clarified it for me :)
Gary.
Quote from: DeepCut on December 04, 2010, 01:21:39 PM
Thanks both of you that's totally clarified it for me :)
Gary.
Did it? Let's see if I can muddy the waters a bit then.
:P
Your original question wasn't answered, though, and although the answers you got are correct they don't clear up the confusion, IMHO, so here's my two dollars worth:
The original question: "If my 1kW heater was on for 3 minutes, how many watts would it have used ?"
And the answer -- which I don't see in the otherwise excellent answers -- is 1000 Watts. (not "Used" but "dissipated" is preferred)
This is because the Watt is a unit of power and is "instantaneous" --- and more importantly IS NOT A CONSERVED QUANTITY in that the number of Watts "into" a system does not necessarily equal the number of Watts "out".
The Watt is a Rate of Energy Usage. Energy is the conserved quantity: what goes in is equal to what comes out. But it doesn't have to come in and go out at the same Rate...and that's what seems to trick a lot of people into thinking they've got OU or COP>1 when all they've done is amplify power, instead of energy.
So, since the Watt is a Rate, your question is like asking: If I drive my car at 60 miles per hour for three minutes, how fast am I going?
Of course you are going 60 miles per hour.
But what's important is not how fast but how far: How Far do you go in 3 minutes at 60 mph?
If you are using 1 kiloWatt for 3 minutes, how much ENERGY have you used in that time?
So the Watt, a unit of Power, is defined as a Rate of Energy Usage: 1 Watt = 1 Joule per Second. The Joule is the accepted Energy Unit in SI.
So "how far", not "how fast" becomes 1 kW for 3 minutes = 1 kW for 180 seconds = 1000 joules/second * 180 seconds = 180,000 Joules of energy "used".
Or rather, transferred from electricity to heat.
Thanks TK, excellent detail :)
Gary.
@All,
While we are on the subject of heating. How many infrared LED's would be needed, running off a Joule Thief/boost converter, to put out 3412 BTUs? :)
The LEDs would be placed in a mirrored tube as in this patent configuration:
"#7133604 Infrared air heater with multiple light sources and reflective enclosure"
http://www.freepatentsonline.com/7133604.html
One BTU is 1055 Joules. 3412 BTU, then, is about 3.6 megaJoules.
But again, you will note that heating and cooling systems are rated in BTU/hour, not just BTU. BTU, then, is an energy value, not a power value, and can express, for example, the energy content of a fuel or power source. (BTU/liter for example).
All the power you put into the system will eventually come out as heat.
The IR diodes can be chosen in many power ranges, but let's choose nice fat 100 mW ones. That's one-tenth of a Joule per second of operation. So your question, again, isn't how "fast" but how "far"...how LONG can you run, say, a bank of 10000 x 100 mW IR LEDs on 3412 BTUs.
10000 x 100 mW = 1000 Watts, or 1000 Joules/second.
An energy store of about 3,600,000 Joules, dissipated at the rate of 1000 Joules per second (that is, 1000 Watts) , will run out in about 3,600 seconds or 60 minutes.
Unless I misplaced a decimal somewhere.
I think we should digitize TK's brain, put it in a yottabyte database, add speech synthesis and speech recognition.
Gary.
if i had known TK was going to answer i would have been happy to let him as he
does it so much better.
fritznien
Thank you TinselKoala,
10000 IR LEDs :o , they don't make those as Christmas lights either. In other words it still more efficient to burn solid fuel.
Hi Gary,
If you are trying to heat a small room with a 1kw heater you could try a 250watt heat lamp or two to reduce the power.
I had an idea of running a bank of heat lamps then when the heat starts to get comfortable switch them down one at a time. 1000, 750, 500, 250, 100, 75 watt heat lamps. You might need a fuzzy logic controller to switch them as the temperature changes. This way your not running the full 1kw load of the heater as the temperature goes up and only increasing one level to maintain the current temperature.
simple answer:
;)
10,000 LEDs??... im sure Tseung must have had those lit on full brightness using peak-to-peak voltage measurements by now ::)
@e2matrix
What a beautiful little piece of kit !
Is that something from the early 20th century ?
Gary.
@all
Be careful with the IR Led thing and BTU's. Btu is fully sensable heat which
means a black-body spectrum shape of fully random molecular motion. IR leds
are going to have a particular spectral peak that the IR leds drive EMF at. These
different spectrum shapes don't seem like much but they can be if someone is
discussing overunity. IR heat will become BTU's with time, but the leds may
have made more IR during that time too.
:S:MarkSCoffman
Quote from: DeepCut on December 05, 2010, 12:03:37 PM
@e2matrix
What a beautiful little piece of kit !
Is that something from the early 20th century ?
Gary.
I just grabbed that pic off eBay as I didn't have any pics handy of my own. I've got 4 of these mechanical kilowatt hour meters beside the one on my house. The ones I've got work on both 120 or 240 volt and many of these are still in use in many areas although I know some have gone to the digital meters. I think from what I know about them that if FE experimenters were to use these to validate any real power input/output measurements there would be no doubt about whether you have a real overunity device. The ones I have are made by GE and have manufacture date stamps between 1979 and 1985.
Thanks e2 i'll look for one on ebay, it looks good as well as being incredibly handy.
Thanks,
Gary.
Quote from: DeepCut on December 03, 2010, 11:39:43 PM
Hi.
I've just read this : http://en.wikipedia.org/wiki/Power_%28physics%29
but i don't understand how i would calculate say, if my 1kW heater was on for 3 minutes, how many watts would it have used ?
Apply Wikipedia formula P=dw/dt, or dw=P*dt.
If P is constant during a time interval Î"t, then we can write: w=P*Î"tw the energy in KWh, P the power in KW, Î"t the time in h.
or
w the energy in Joule, P the power in W, Î"t the time in s.
Here: P = 1kW, Î"t = 3mn = 3/60h = 0,05h
Thus w = P*Î"t = 1Kw * 0.02h = 0.05 KWh (= 50Wh).
If t is expressed in seconds and P in watts, then w is in joule:
Here w = 1000W * (3*60)s = 180 000 J.
A 1 Kw heater during 3 mn has consumed 50Wh or 180 000J.