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Interesting argument between friends

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sophiecentaur
#55
Nov19-12, 11:49 AM
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Quote Quote by LawRooney View Post
If we are talking about purely heat, then yes, I guess they would give off the same amount of heat.

But if some guy is trying to argue that using a 1000W computer will keep you as warm as a 1000W heater will, I'd say that guy definitely needs to switch majors.

I guarantee a heater gives off more heat per second than a computer.
That is rubbish, I'm afraid. How is one KiloWatt different from another Kilowatt? The only possible difference in the energy supplied to the room would be in the light power that escapes through the window from the monitor (perhaps a Watt).

We have already been into the fact that supplying 1kW to a room is not the whole story when it comes to making people feel warm but that is not the issue.

Hmm - fools rush in, you know.
Windadct
#56
Nov19-12, 02:01 PM
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All I can say is that a 1000W computer - is it's rated value, full power. So just because the rating is 1000W, does not mean you are using all of that 1000W - If you max out the power supply - then ALL of the 1000W it consumes is left as residual heat.

I would also like to add that Sound and EM are not the only ways to consume the energy - think of all of the ways you can do work ( affect a change in a system) and not give off heat. For example all of the ways to convert to Potential Energy - for example a 1000W Battery charger does NOT give off 1000W of heat.
russ_watters
#57
Nov19-12, 02:48 PM
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Quote Quote by LawRooney View Post
If we are talking about purely heat, then yes, I guess they would give off the same amount of heat.

But if some guy is trying to argue that using a 1000W computer will keep you as warm as a 1000W heater will, I'd say that guy definitely needs to switch majors.

I guarantee a heater gives off more heat per second than a computer.
That is self-contradictory: either the numbers are equal or they aren't.
sophiecentaur
#58
Nov20-12, 05:14 AM
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Quote Quote by Windadct View Post
All I can say is that a 1000W computer - is it's rated value, full power. So just because the rating is 1000W, does not mean you are using all of that 1000W - If you max out the power supply - then ALL of the 1000W it consumes is left as residual heat.

I would also like to add that Sound and EM are not the only ways to consume the energy - think of all of the ways you can do work ( affect a change in a system) and not give off heat. For example all of the ways to convert to Potential Energy - for example a 1000W Battery charger does NOT give off 1000W of heat.
Obviously 'rating' is not what counts and a battery charger is a valid exception but that's only finding loopholes in an argument which was dealing with the notion that dissipated energy is somehow different, according to what's written on the front panel label of the equipment.

And, before questioning just how much heat a computer can generate, just consider the vast amount of trouble they have in getting rid of all the heat in a big Server Room. It's a serious problem.
rbj
#59
Nov20-12, 06:35 PM
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Quote Quote by LawRooney View Post
If we are talking about purely heat, then yes, I guess they would give off the same amount of heat.

But if some guy is trying to argue that using a 1000W computer will keep you as warm as a 1000W heater will, I'd say that guy definitely needs to switch majors.

I guarantee a heater gives off more heat per second than a computer.
if the room is windowless and if the room is completely sound insulated (note neither of these conditions are about either the heater or the computer) and if both the heater and the computer have watt-meters attached and both are drawing the same power of W watts, then I guarantee that you're incorrect, Rooney. they will both heat the room exactly the same.
LawRooney
#60
Nov21-12, 02:34 AM
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Quote Quote by rbj View Post
if the room is windowless and if the room is completely sound insulated (note neither of these conditions are about either the heater or the computer) and if both the heater and the computer have watt-meters attached and both are drawing the same power of W watts, then I guarantee that you're incorrect, Rooney. they will both heat the room exactly the same.
Yeah, I don't see how I would be incorrect. I made no statement whatsoever about an "ideal room" and simply stated that a heater would obviously warm you up better, even if the total amount of heat given off ended up being the same.
Averagesupernova
#61
Nov21-12, 09:45 AM
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Quote Quote by LawRooney View Post
Yeah, I don't see how I would be incorrect. I made no statement whatsoever about an "ideal room" and simply stated that a heater would obviously warm you up better, even if the total amount of heat given off ended up being the same.
I suppose you could say that if you are sitting in front of the heater.
-
Let me ask you this: Take 4 incandescent light bulbs of 250 watts each mounted on a board. Then take a 1000 watt radiant heater of the same area as the board. Which one do you think will warm you up better?
rbj
#62
Nov22-12, 12:11 AM
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Quote Quote by LawRooney View Post
Yeah, I don't see how I would be incorrect. I made no statement whatsoever about an "ideal room"
well, i just wanted to plug leaks. photons or phonons that leave the room won't heat it. so i wanted to make clear that none were.

and simply stated that a heater would obviously warm you up better, even if the total amount of heat given off ended up being the same.
and that's incorrect. they're both giving off the same amount of heat.
es1
#63
Nov22-12, 11:26 AM
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Quote Quote by LawRooney View Post
I guarantee a heater gives off more heat per second than a computer.
Your intuition is likely right but your terminology is wrong. What I suspect you're thinking is if I place a computer in one cold room and a (well designed) space heater in another, turn them both on, return in 30 minutes, then the room with the computer will have a lower ambient temp rise.

I suspect this is right because the thermal resistance of the space heater is likely lower than that of the computer case. Or to put it another way, the computer needs to heat itself more than a space heater before it can heat the room so its startup time is longer.

This effect really only matters on short time scales (there needs to be a point where the computer is releasing all the heat it produces or it will continue to rise in temp) and the initial assumption in the thread told us to ignore this effect.

Also, a real computer connected to a 1KW supply likely does not draw constant 1KW as the power supply is sized for the worst, not typical, case. But again, the initial assumption stated in this case the computer does.

http://en.wikipedia.org/wiki/Thermal_resistance
sophiecentaur
#64
Nov22-12, 12:31 PM
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Quote Quote by es1 View Post
What I suspect you're thinking is if I place a computer in one cold room and a (well designed) space heater in another, turn them both on, return in 30 minutes, then the room with the computer will have a lower ambient temp rise.

I suspect this is right because the thermal resistance of the space heater is likely lower than that of the computer case.
Actually, I suspect that a rack of processors consuming at 1kW will need to be very well cooled and the fans will soon be pumping out the heat at the full 1kW rate because they do not want the internal temperature to get more than the optimum. They have to be as good to the stuff inside the boxes as you r heating system needs to be at home - and with a similar thermal time constant.
OmCheeto
#65
Nov22-12, 01:08 PM
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Quote Quote by JustNobody View Post
...
My EE friend has a theoretical heater which runs on 1000 watts of power. In his apartment he also has another electronic device (ie. a computer, a television ect) which also requires 1000 watts to run. He argues that, due to conservation of energy, 1000 watts is 1000 watts and the same amount of heat will be produced from his "device" as from his heater (and thus if his theoretical device is always running at 1000 watts he will never need to turn out his heater to heat his house).
I agree with your friend. I have a macbook, and when I installed the SETI* software, the fan came on. Sounded like a jet engine inside my laptop. I uninstalled the SETI software. Nothing I did before, nor since, has made my fan work that hard.

I have two spare tower PC's that I no longer use, and have considered starting them up in the winter months running the SETI software. I'm a very big fan of cogeneration, (also known as combined heat and computing, CHC )

hmmm.....

Quote Quote by Om's Macbook
Battery Information:
...
Full Charge Capacity (mAh): 4565
Voltage (mV): 12492
...
I think my battery routinely lasts for 6 hours, so it would appear to be consuming:
4.565Ah * 12.492V / 6 hours = 9.5 watts

Time my laptop battery would survive if my laptop were drawing 1000 watts:

57.0 wh/1000 watts = 3.42 minutes





Thank you,
You're welcome.



---------------------------------
* I do not mean to imply in any way that I am promoting the History Channel.
sophiecentaur
#66
Nov22-12, 01:19 PM
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Puts me in mind of Crocodile Dundee, comparing a laptop and an Internet Server "That's not a computer - this is a computer" (knife).
OmCheeto
#67
Nov22-12, 02:46 PM
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Quote Quote by sophiecentaur View Post
Puts me in mind of Crocodile Dundee, comparing a laptop and an Internet Server "That's not a computer - this is a computer" (knife).
I've never seen a real Internet Server.

But this is starting to remind me of Thanksgiving, and the fact that I'm a metaphor whore....


Quote Quote by Borek View Post
Happy Thanksgiving!
Matherole?

I so want to use that in the "How do magnets work" thread.

Quote Quote by Meta Crazy Om
So you've got these green beans, and through some poly-dimensional gearing mechanism, do something quite extraordinary.......

----------------------------------
/me hides from the donderbolts.
sophiecentaur
#68
Nov23-12, 05:48 AM
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Quote Quote by OmCheeto View Post
I've never seen a real Internet Server.

But this is starting to remind me of Thanksgiving, and the fact that I'm a metaphor whore....




Matherole?

I so want to use that in the "How do magnets work" thread.




----------------------------------
/me hides from the donderbolts.
Never heard the word Materhole before but, when googling, I found this, totally randomly, on YouTube_Nerdy or what???

Do you think she could be a recruit for PF?
OmCheeto
#69
Nov23-12, 08:52 AM
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Quote Quote by sophiecentaur View Post
Never heard the word Materhole before but, when googling, I found this, totally randomly, on YouTube_Nerdy or what???

Do you think she could be a recruit for PF?
Borek posted 4 of her videos:

Quote Quote by Borek View Post
Happy Thanksgiving!

Fractal Thanksgiving Turduckenen-Duckenen
Mathed Potatoes (with a visual display of a brute force algorithm)
Green Bean Vector Matherole
Borromean Onion Rings

I suppose PF is one of these places where this approach to Thankgiving will be appreciated!
It's not often I will finish one video, much less 4. I would very much like to invite her to the forum. She could make videos for us!

"How to cook a 15 lb. Fractal Thanksgiving Turduckenen-Duckenen with a pair of 1000 watt Personal Computers in under X* hours."

----------------------
* Does anyone know the specific heat capacity of turkey?
Oh never mind. Google apparently now knows everything:
thanks to Ciaran for this great link from the Engineering ToolBox that lists the specific heat capacity of a turkey as 2.81 x 103J/(kg C).

But I have to go to work now. I'll solve for "X" tomorrow.


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