What is the effect of scaling down a heat exchanger?

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SUMMARY

Scaling down heat exchangers significantly enhances heat flow by minimizing the distance heat must travel from a CPU's hotspot to the heat collector, thereby reducing thermal resistance. However, this reduction in size can lead to decreased heat capacitance due to reduced mass, potentially resulting in higher temperatures while removing smaller amounts of energy. The thermal conductance of silicon also diminishes at elevated temperatures, which may counteract the benefits of decreased travel distance. The overall effectiveness of scaling down depends on the balance between these competing thermal properties.

PREREQUISITES
  • Understanding of thermal resistance in heat exchangers
  • Knowledge of heat capacitance and its impact on thermal performance
  • Familiarity with thermal conductance properties of materials, particularly silicon
  • Basic principles of heat transfer in CPU cooling systems
NEXT STEPS
  • Research the effects of heat exchanger scaling on thermal resistance
  • Explore the relationship between heat capacitance and thermal performance in micro-scale systems
  • Investigate advanced materials with higher thermal conductance at elevated temperatures
  • Learn about optimizing heat exchanger designs for CPU cooling efficiency
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Engineers, thermal management specialists, and anyone involved in CPU cooling system design and optimization will benefit from this discussion.

JessEE92
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According to this article, it is beneficial to scale down heat exchangers due to the decreased distance the heat has to travel, and therefore the decreased thermal resistance and increased heat flow.

"the best way to remove heat from a CPU is to minimize the distance heat must travel from a CPU's hotspot to the heat collector before it's carried away"

However what confuses me is that their are more things that affect heat flow than travel distance, and to me it seems that scaling down the heat exchanger to micro and nano scales would be detrimental to performance. For example the heat capacitance of the exchanger will go down with its reduced mass, therefore it will get to much hotter temperatures while removing smaller amounts of energy. The thermal conductance of silicon decreases for hotter temperatures so this will decrease heat flow.

It all depends on how the properties scale. Will the advantage of decreased travel distance outweigh the disadvantage of lower heat capacity as you scale down?

My second question is: Are there other relevant properties (thermal or otherwise) that are effected by scaling heat exchangers?

Here is a diagram of the heat exchanger in question:

figure_02.gif
 
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What they are doing is reducing the thermal resistance between the die and the coolant. That is made up of two parts in series...

1) Thermal resistance between die and heat collector.
2) Thermal resistance between heat collector and coolant.

This proposal reduces 2).

They aren't necessarily reducing the surface area but are fitting the required surface area into a smaller space.
 

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