possible sollution for heat problems in notebooks

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Posted:
in Future Apple Hardware edited January 2014
I was just reading this thing on apple's news page about the virginia tech cluster. There's a line in there"



" If you've ever sat with a TiBook in your lap, you understand that there is a further significant issue. As hot as a G4 runs, a G5 runs hotter."



I was thinking about that notebook thing and thought the main reason for poor battery life in laptops is not that the batteries are crap (though of course they could be better) but it's the fact that processors are very inefficient in power consumption. And how exactly do we notice that?

Why just as we do with lightbulbs, HEAT. I believe a lightbulb only converts about 5 percent of it's wattage into light, the rest is converted into heat. Now, in processors it seems to me to be much the same, the efficiency is probably higher than 5% but I doubt it would exceed 40% or so.... I dunno.

The thing is, there are devices that convert light into electricity, devices that convert kinetic energy into electricity, we're trying all these things to power our portable devices. Yet in a notebook, there already is a powersourse, the processor and even the battary itself are powersources heatwise. Isn't there a way to convert perhaps half or even a quarter of that heat back into electricity ? ? ? you could have it charge a backup battery or the running battery itself (dunno if that works well) and you'll take away a percentage of the heat by converting it back into electricity.

Thus making your device far more efficient in stead of trying to find all them hight tech work arounds....



Am I babbling here ?

Comments

  • Reply 1 of 15
    tfworldtfworld Posts: 181member
    That would be a great idea, but then it starts to sound like a perpeptual energy device... They need to just make a small steam power plant in the notebook!



    In reality, converting heat to energy takes more room than a laptop will provide. Unless they find an alloy that will naturally do this, it wont happen for a long time.
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  • Reply 2 of 15
    ~ufo~~ufo~ Posts: 245member
    OR:



    make a laptop thermos hybrid !



    huh ? huh ?



    how'bout them apples ! ? !



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  • Reply 3 of 15
    tfworldtfworld Posts: 181member
    Hey yeah, they can attach it via hotwire! The new slogan for Apple, we can keep your coffee hot too!
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  • Reply 4 of 15
    You mean something like this:



    Technology Research News



    The question is can you fit them into laptops?
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  • Reply 5 of 15
    ~ufo~~ufo~ Posts: 245member
    aye



    but 18% efficiency wouldn't really be worth it....



    glad to see there is development going on though. :-)



    makes me feel sane again
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  • Reply 6 of 15
    tjmtjm Posts: 367member
    Quote:

    Originally posted by neumac

    You mean something like this:



    Technology Research News



    The questions is can you fit them into laptops.




    Note that they get 18% efficiency with an input heat source of 200-300 °C. Processors start to fail considerably below that. We would have to get the processors glowing cherry-red before these devices would be practical.



    ~ufo~ has raised a good question, but the problem remains insoluble at this point. Direct thermoelectric conversion is too inefficient even with these new breakthroughs. Other methods to effect a conversion of the heat back to electricity involve too much bulk and mechanical complexity. At the moment, the cheapest, simplest alternatives are better batteries and asbestos underwear, unfortunately.
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  • Reply 7 of 15
    thttht Posts: 5,805member
    Quote:

    Originally posted by ~ufo~

    Am I babbling here ?



    No.



    I have a sneaky suspicion that a device that can convert heat into electrical energy will be a MEMS device, not a semiconductor one. Essentially your regular old fluid driven - coal, nuclear, gas, whatever - power plant, shrunk down to nano or micro size.
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  • Reply 8 of 15
    yevgenyyevgeny Posts: 1,148member
    Quote:

    Originally posted by THT

    No.



    I have a sneaky suspicion that a device that can convert heat into electrical energy will be a MEMS device, not a semiconductor one. Essentially your regular old fluid driven - coal, nuclear, gas, whatever - power plant, shrunk down to nano or micro size.




    All of which will fit into a 1 inch form factor and will at best only give you a 20% increase in battery life at a large cost? I don't think so. Apple would ship a better battery before such a device.
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  • Reply 9 of 15
    neutrino23neutrino23 Posts: 1,564member
    Nice ideas but not really practical. You can calculate the maximum efficiency of any heat engine as the difference in temperature from input to output divided by the input temperature (Kelvin).



    In this case lets say the chip could run about 360K and the cool end of the converter might run about 300K. This means the maximum efficiency would be about 16%. That would add about 25 minutes to a system that otherwise ran four hours. In the real world the efficiency would and benefit would be much less. Hardly worth the effort.



    All such devices are based on a temperature difference. If you don't somehow remove heat from the cold end it will warm up and the device will stop functioning.
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  • Reply 10 of 15
    thttht Posts: 5,805member
    Quote:

    Originally posted by Yevgeny

    All of which will fit into a 1 inch form factor and will at best only give you a 20% increase in battery life at a large cost? I don't think so. Apple would ship a better battery before such a device.



    Well, yeah in the near term. But down the line when such a device could be in production, could fit in a 1 inch factor, and when mobile laptops are using 60 Watt CPUs, such a thing would be really handy.
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  • Reply 11 of 15
    thttht Posts: 5,805member
    Quote:

    Originally posted by neutrino23

    All such devices are based on a temperature difference. If you don't somehow remove heat from the cold end it will warm up and the device will stop functioning.



    Would a MEMS scale device be more efficient?
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  • Reply 12 of 15
    mmicistmmicist Posts: 214member
    Quote:

    Originally posted by THT

    Would a MEMS scale device be more efficient?



    No.



    This is a maximum theoretical efficiency for any heat engine. Any real machine would be hard pushed to come anywhere near it, and in practice, the lower the temperature difference available, the more difficult it is to approach the theoretical limit.



    michael
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  • Reply 13 of 15
    boemaneboemane Posts: 311member
    Quote:

    Originally posted by ~ufo~

    aye



    but 18% efficiency wouldn't really be worth it....



    glad to see there is development going on though. :-)



    makes me feel sane again




    Another way of doing this would be to make batteries that are AC powered ? Each time the power turns, the battery would be charged a little, prolonging its life. Power would eventually run out since it takes more power to charge a battery than you get when discharging it..



    A true project for mad scientists



    .:BoeManE:.
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  • Reply 14 of 15
    thttht Posts: 5,805member
    Quote:

    Originally posted by mmicist

    This is a maximum theoretical efficiency for any heat engine. Any real machine would be hard pushed to come anywhere near it, and in practice, the lower the temperature difference available, the more difficult it is to approach the theoretical limit.



    Yes, you guys are right. Should have taken some time to think about it. I'm still questioning it however since the physics at MEMS scales would operate a little differently then they do at large scales...



    Anyways, I would take that 15%.
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  • Reply 15 of 15
    Trust me, many people have investigated this subject to death. There is just not much usable energy that can be recovered from a temperature difference of only about 50C.



    It would be better to put the effort into developing new technologies that use less power to start with. OLED displays will use less power compared to LCDs. New generations of HDs seem to use less power. Newer CPUs might use less power. Better power management strategies will cut down average power use.



    If small improvements to all of these methods cuts down power requirements by ten percent that is probably a much bigger benefit than you could get by trying to get energy from a hot CPU.
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