By: David Hess (davidwhess.delete@this.gmail.com), June 25, 2011 4:12 am
Room: Moderated Discussions
bakaneko (no@spam.org) on 6/24/11 wrote:
---------------------------
>Ricardo B (ricardo.b@xxxxx.xx) on 6/24/11 wrote:
>---------------------------
>>I'm afraid you're quite wrong.
>>It's not a mere matter of air flow.
>>
>>Besides airflow, there are two more key parameters in the transfer of heat to air:
>>the contact area and the temperature difference between the contact area and the air.
>>
>>In order to maximize heat radiation you want your heat sink to have as much contact
>>area as possible. Thus, the heat sink designs with lots of big fins.
>>
>>However, there's a catch. The material's (aluminium, copper) thermal resistance will produce a temperature gradient.
>>That is, the heatsink will always be hotter at the base and cooler at the edges.
>>
>>This means that increasing the contact area has diminishing benefits: you increase
>>area, but a greater part of that are is cooler and radiates less heat.
>>
>>Enter water cooling.
>>With a circulating fluid, like water or oil, the temperature gradients are much smaller.
>>In turn, this allows for radically different radiator designs, with a much larger and effective contact area.
>
>What about heat pipes? They do basically the same, but without forcing
>you to use a complex system to control the fluid, are a closed system
>and can be used with passive cooling.
Heat pipes have a much lower thermal resistance than even circulated water but also have a power density limitation of about 10 to 30 watts per square centimeter at the evaporator depending on the construction so a heat spreader is needed. You could not for instance apply the heat pipe working fluid directly to the integrated circuit die.
---------------------------
>Ricardo B (ricardo.b@xxxxx.xx) on 6/24/11 wrote:
>---------------------------
>>I'm afraid you're quite wrong.
>>It's not a mere matter of air flow.
>>
>>Besides airflow, there are two more key parameters in the transfer of heat to air:
>>the contact area and the temperature difference between the contact area and the air.
>>
>>In order to maximize heat radiation you want your heat sink to have as much contact
>>area as possible. Thus, the heat sink designs with lots of big fins.
>>
>>However, there's a catch. The material's (aluminium, copper) thermal resistance will produce a temperature gradient.
>>That is, the heatsink will always be hotter at the base and cooler at the edges.
>>
>>This means that increasing the contact area has diminishing benefits: you increase
>>area, but a greater part of that are is cooler and radiates less heat.
>>
>>Enter water cooling.
>>With a circulating fluid, like water or oil, the temperature gradients are much smaller.
>>In turn, this allows for radically different radiator designs, with a much larger and effective contact area.
>
>What about heat pipes? They do basically the same, but without forcing
>you to use a complex system to control the fluid, are a closed system
>and can be used with passive cooling.
Heat pipes have a much lower thermal resistance than even circulated water but also have a power density limitation of about 10 to 30 watts per square centimeter at the evaporator depending on the construction so a heat spreader is needed. You could not for instance apply the heat pipe working fluid directly to the integrated circuit die.
Topic | Posted By | Date |
---|---|---|
Article: Cooling and performance/watt | David Kanter | 2011/06/21 12:19 PM |
'temperature' not 'power'? | Paul A. Clayton | 2011/06/21 03:01 PM |
'temperature' not 'power'? | David Kanter | 2011/06/21 03:38 PM |
resistance(temperature) | Moritz | 2011/06/22 04:48 AM |
resistance(temperature) | Adrian | 2011/06/22 05:13 AM |
resistance(temperature) | David Hess | 2011/06/22 08:53 AM |
resistance(temperature) | Adrian | 2011/06/24 02:24 AM |
resistance(temperature) | David Hess | 2011/06/24 02:14 PM |
Article: Cooling and performance/watt | Ed Trice | 2011/06/22 10:57 AM |
Cooling | David Kanter | 2011/06/22 03:26 PM |
Cooling | Ed Trice | 2011/06/22 03:54 PM |
TE-elements | Moritz | 2011/06/23 05:55 AM |
Radiator placement and design | Ricardo B | 2011/06/23 07:34 AM |
TE-elements | EduardoS | 2011/06/23 04:21 PM |
water/air | Moritz | 2011/06/23 10:30 PM |
water/air | Ricardo B | 2011/06/24 02:29 PM |
water/air | bakaneko | 2011/06/24 09:45 PM |
water/air | David Hess | 2011/06/25 04:12 AM |
water/air | Ricardo B | 2011/06/25 06:07 AM |
water/air | ZaZa | 2011/06/25 09:47 AM |
water/air | Ricardo B | 2011/06/25 11:40 AM |
water/air | rwessel | 2011/06/26 03:43 AM |
water/air | ZaZa | 2011/06/26 04:05 PM |
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Temperature inversion | Vincent Diepeveen | 2011/06/27 01:01 PM |
Temperature inversion | Anon | 2011/06/28 03:30 PM |
Temperature inversion | Jonathan Kang | 2011/07/05 06:38 PM |
Article: Cooling and performance/watt | (tm) | 2011/06/27 05:51 AM |
Article: Cooling and performance/watt | David | 2011/10/15 06:14 PM |
Article: Cooling and performance/watt | rwessel | 2011/10/15 09:56 PM |
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Exponential growth of subthreshold leakage | Rohit | 2011/12/15 01:22 PM |
Exponential growth of subthreshold leakage | David Kanter | 2011/12/15 04:20 PM |
Exponential growth of subthreshold leakage | Iain McClatchie | 2013/01/07 12:28 AM |
Exponential growth of subthreshold leakage | Doug S | 2013/01/07 10:25 AM |
Exponential growth of subthreshold leakage | someone | 2013/01/07 11:12 PM |
Article: Cooling and performance/watt | Robert Pearson | 2021/07/26 09:45 AM |