Interesting argument between friends

[Averagesupernova]

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]

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]

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]

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]

...
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...

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]

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]

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...

Happy Thanksgiving!

Matherole?

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

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

----------------------------------
/me hides from the donderbolts.

 

[sophiecentaur]

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]

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:

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.