How does the Iphone cool itself?

[Carlos1010]

Hi all,

Just for curiosity, how does a iPhone or smartphones in general cool itself and the APU? I can't hear any fans when my room is silenced, how it that possible? IT is cooled by the holes the phone has so that air goes through it or? Thanks in advanced! 

[ARikozuM]

It's passively cooled by the aluminum chassis.

[Carlos1010]

2 minutes ago, ARikozuM said:

It's passively cooled by the aluminum chassis.

But without a fan, how does it cool?

[Enderman]

1 minute ago, Carlos1010 said:

But without a fan, how does it cool?

The aluminum on the phone is hotter than the surrounding air, so heat magically transfers from the phone to the air.

 

[roblesaturcamilo]

well... no fans for sure...

 

i think that first the smartphones cpu's have very low TDP, and thus they produce just a bit of heat (compared to bigger devices)

 

also i guess that in case of overheat, they will just throttle just like any cpu...

 

and if the heat goes way too high they will enter in protection mode, not allowing you to use the phone or just powering off completely...

[roblesaturcamilo]

4 minutes ago, ARikozuM said:

It's passively cooled by the aluminum chassis.

there are a lot of phones that does not have aluminum body, also none of the phones' cpu touches the body in any phone...

[ARikozuM]

2 minutes ago, Carlos1010 said:

But without a fan, how does it cool?

Diffusion, essentially. The phone's chassis is hotter and thus cools itself by giving its heat to the surrounding air.

[ARikozuM]

Just now, roblesaturcamilo said:

there are a lot of phones that does not have aluminum body, also none of the phones' cpu touches the body in any phone...

Those phones have TDP's much lower and are still passively cooled.

[roblesaturcamilo]

1 minute ago, ARikozuM said:

passively cooled.

the concept of passive cooling remains when something (call it a piece of aluminum, heatsink of whatever you like) is in direct contact with the hot element in question...

 

the fact that your whole phone gets warm (or hot, whatever...) is because of something called thermal radiation, it happens when the hot element is close enough to other object to heat it up (but not touching it...)

 

this thermal radiation will not cool down the hot element directly, but it can ABSORB the residual heat produced by the hot element. ..

 

basic thermodinamics law...

[TubsAlwaysWins]

17 minutes ago, Carlos1010 said:

But without a fan, how does it cool?

As far as I know there arent any phones with fans. They are all cooled passively by having the processor touch the shell

[roblesaturcamilo]

Just now, TubsAlwaysWins said:

They are all cooled passively by having the processor touch the shell

show me one phone processor touching the shell... A SINGLE ONE!!!

[ARikozuM]

8 minutes ago, roblesaturcamilo said:

show me one phone processor touching the shell... A SINGLE ONE!!!

Heatpipe-cooling (vapor chamber)

http://www.techworm.net/2016/02/samsungs-galaxy-s7-first-smartphone-feature-clever-liquid-cooling-system.html

 

Most phones use passive cooling. Since you've quoted thermodynamics, surely you know of the 2nd Law. It (in a nutshell) states that equilibrium will be reached for all energies. This means that every object (processor, air, aluminum/plastic) will want to maintain their thermal energy at the same levels internally and externally.

[roblesaturcamilo]

1 minute ago, ARikozuM said:

"first smartphone"

that's all i'm gonna say (quote)

[roblesaturcamilo]

24 minutes ago, roblesaturcamilo said:

show me one phone processor touching the shell

 

5 minutes ago, ARikozuM said:

Heatpipe-cooling (vapor chamber)

 

give up

[ARikozuM]

Just now, roblesaturcamilo said:

that's all i'm gonna say (quote)

The processor doesn't need to touch the aluminum directly to be cooled by it. You're also thinking of phones who thermal design power is sub-20W.

[Dabombinable]

The aluminum back acts as a finless heatsink. It might not be as efficient as a heatsink with fins, but not much is needed to cool the majority of ARM based CPU.

[Carlos1010]

1 hour ago, Enderman said:

The aluminum on the phone is hotter than the surrounding air, so heat magically transfers from the phone to the air.

 

Well, if its hotter doesnt that mean that it makes the APU hotter too?

[Carlos1010]

54 minutes ago, roblesaturcamilo said:

the concept of passive cooling remains when something (call it a piece of aluminum, heatsink of whatever you like) is in direct contact with the hot element in question...

 

the fact that your whole phone gets warm (or hot, whatever...) is because of something called thermal radiation, it happens when the hot element is close enough to other object to heat it up (but not touching it...)

 

this thermal radiation will not cool down the hot element directly, but it can ABSORB the residual heat produced by the hot element. ..

 

basic thermodinamics law...

So when it absorbes it, where does it put the heat? I cant feel anything hot near my phone too. 

[roblesaturcamilo]

1 minute ago, Carlos1010 said:

So when it absorbes it, where does it put the heat? I cant feel anything hot near my phone too. 

bassically your whole phone will heat up, but depending on the phone this will be more evident in some than others...

 

on a plastic shell phone, most of the times, you won't fell the phone warming up, and if you do it will be very little...

 

on a iphone for example, you will fell the phone heating up, but it is so little that you can confuse the phone's heat with your own hands heat...

 

and by the way, to make a phone heat up, you need to push it with cpu/gpu intensive tasks like gaming and stuff...

 

or battery consuming tasks like watching videos with full brightness and volume for a long while, but in this case it will be more likely the battery heating up... 

[pyrojoe34]

6 hours ago, roblesaturcamilo said:

the concept of passive cooling remains when something (call it a piece of aluminum, heatsink of whatever you like) is in direct contact with the hot element in question...

 

the fact that your whole phone gets warm (or hot, whatever...) is because of something called thermal radiation, it happens when the hot element is close enough to other object to heat it up (but not touching it...)

 

this thermal radiation will not cool down the hot element directly, but it can ABSORB the residual heat produced by the hot element. ..

 

basic thermodinamics law...

I think the role thermal radiation plays in this case is probably pretty small. It's probably mostly conduction and convection.