Why are all the heatsinks round?

DaveInCave

DaveInCave

Well-Known Member
I was sure heat dissipation is a function of surface area.
As such, don't round and spherical shapes have the minimal surface area for a given radius?

I would expect heatsinks to be as cuboid as possible to maximize the surface area within an envelope.
Can someone explain this?

Thanks!
 
Rahz

Rahz

Well-Known Member
DaveInCave said:
I was sure heat dissipation is a function of surface area.
As such, don't round and spherical shapes have the minimal surface area for a given radius?

I would expect heatsinks to be as cuboid as possible to maximize the surface area within an envelope.
Can someone explain this?

Thanks!
Click to expand...
The corners of a square heat sink are further from the cob. Rather than a square the material is better invested in making the round design a little larger.
 
DaveInCave

DaveInCave

Well-Known Member
Rahz said:
The corners of a square heat sink are further from the cob. Rather than a square the material is better invested in making the round design a little larger.
Click to expand...
But as you make the circle bigger, the edges will end up being just as farther away from the cob as the corners, won't they?
 
xX_BHMC_Xx

xX_BHMC_Xx

Well-Known Member
I think what Rahz is trying to say, in layman's terms, is that the heat distribution will be much more even among all fins/pins with a circular heatsink than a square/rectangle. Anyone that has a HSUSA heat sink will notice that their corners will be cooler (or hotter, depending on config.) than the middle/center. This makes the circular unit, as a whole, more effective.
 
robincnn

robincnn

Well-Known Member
DaveInCave said:
Yet the pins are cylindrical, is it because it's easier to manufacture?
Click to expand...
Cylenderical pins will work the same for any air stream direction.
Pins come in fin rectangle shape too.
Air moves differently with those. Fluid dynamics simulations and air streams/ turbulence are too complicated.
You can find pin geometry articles on Google scholar.

As mentioned earlier most are round to keep the material close to source of heat. Aluminum is good conductor of heat but temps fall a little as distance from heat source increases.

For a given length and width, square/rectangle allows you to pack more material/surface area. Like square space of 10mm side. You can put 100mm sq square in it or a pi 5 square = 78.57 mm sq round shape

Size, heat source size, mass , surface area, anodization, pin/fin geometry, orientation, base plate thickness. Too many factors
 
DaveInCave

DaveInCave

Well-Known Member
robincnn said:
Cylenderical pins will work the same for any air stream direction.
Pins come in fin rectangle shape too.
Air moves differently with those. Fluid dynamics simulations and air streams/ turbulence are too complicated.
You can find pin geometry articles on Google scholar.

As mentioned earlier most are round to keep the material close to source of heat. Aluminum is good conductor of heat but temps fall a little as distance from heat source increases.

For a given length and width, square/rectangle allows you to pack more material/surface area. Like square space of 10mm side. You can put 100mm sq square in it or a pi 5 square = 78.57 mm sq round shape

Size, heat source size, mass , surface area, anodization, pin/fin geometry, orientation, base plate thickness. Too many factors
Click to expand...
Great points :) this is super interesting and probably lots of room for research and innovation.
 
Airwalker16

Airwalker16

Well-Known Member
Rahz said:
No, the mass will be closer to center with a circle. You can imagine cutting off the corners and placing them on the side to get them closer to the center. Keep doing this and you end up with a circle.
Click to expand...
Hi @Rahz !!!! Thanks again for EVERYTHING YOU taught me.
 
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