You did the monster math.
Respect.
Comment on Copper
Contramuffin@lemmy.world 2 weeks agoWas bored, so made a simulation to figure it out.
TLDR: 592.2 seconds, or 9 minutes and 52.2 seconds. Very similar to the other comment, so it appears temperature differentials and heat loss to the air are somewhat minor effects compared to the sheer heat mass of the block
Assumptions:
- Copper’s heat conductivity is 400 W/m-K, and specific heat is 0.4 J/g-K, and density is 9000 kg/m^3, and these values do not change over the range of temperatures
- Air’s heat transfer coefficient is 20 W/m^2-K and does not change over the range of temperatures
- The surrounding air does not change in temperature and remains at room temperature (25 C)
- The input wattage is actually 120 W and not just random marketing bullshit
- The copper block’s size is 4 cm x 4 cm x 16 cm (same as other comment)
- The temperature within the copper block differs only by the vertical axis; it is assumed that temperature does not change if you move horizontally into the block
Modeling conditions:
- The block is sliced into 100 equally-sized slices, stacked vertically.
- 120 W is input directly into the bottom slice
- Heat transfer is modeled between each slice
- Heat loss into the air is modeled for each slice (top slice has more heat loss due to more contact with the air)
- Heat changes are calculated per millisecond
- Final time is calculated is the total number of milliseconds it takes for the bottom slice to reach a temperature greater than 100 C
Bahnd@lemmy.world 2 weeks ago
kahjtheundedicated@lemmy.world 2 weeks ago
Respect for taking the time to model that. Goes to show why heat sinks look the way they do, and not just big lumps of metal lol
mnemonicmonkeys@sh.itjust.works 2 weeks ago
Numerical methods is cheating! Real men use PDE’s!
/s of course, though I was kinda hoping you’d use PDE’s
Contramuffin@lemmy.world 2 weeks ago
See, I thought about doing that, but then I realized: I don’t actually want to do that
stoicmaverick@lemmy.world 2 weeks ago
What software did you use to model this, btw?
Contramuffin@lemmy.world 2 weeks ago
Python
kunaltyagi@programming.dev 2 weeks ago
How long a copper block do I need to prevent any throttle?
Contramuffin@lemmy.world 2 weeks ago
Good question. I had to modify my code to run more efficiently, since not throttling implies that the copper block reaches a steady state with very little temperature changes over time.
But, with the changes, I can say that there is no copper block length that would prevent throttling with a 120 W CPU. It seems the heat transfer within the block is slow enough over such long lengths that you get diminishing returns with longer and longer copper blocks. Here’s a graph I made summarizing the different block lengths that I testedImage
Avicenna@programming.dev 2 weeks ago
Have you considered the possibility that Ea-nāṣir might have been delivering inferior quality copper to you?
Contramuffin@lemmy.world 2 weeks ago
Ea-nasir promised that these were good quality copper, and I do not have any reason to suspect otherwise. But I’ll have you know, if the copper is of inferior quality, I will make sure to send my messenger to complain. He will not hear the end of it!
Jumi@lemmy.world 2 weeks ago
Would the result change if the copper block gets wider instead of higher?
Contramuffin@lemmy.world 2 weeks ago
Apparently, yes. You can prevent thermal throttling if you expanded the base from 4 cm x 4 cm to 4.5 cm x 4.5 cm, and if you increased the height from 16 cm to 100 cm. The temperature caps at around 97 C.
Piemanding@sh.itjust.works 2 weeks ago
Did the model include some air movement by way of the fans on the case. That would be a fun thing to think about.
FishFace@piefed.social 2 weeks ago
The fact that the air remains a constant temperature means the model is assuming infinite airflow.
cecinestpasunecommunication@lemmy.dbzer0.com 2 weeks ago
It didn’t model convection at all.
stoicmaverick@lemmy.world 2 weeks ago
Well goddamn… Ok. Go ahead and dm me your home address, phone number, social and/or tax id number, the name of the street you grew up on, the name of your favorite teacher, the IMEI number of your cellphone, a high resolution set of your fingerprints, and a list of your three greatest fears, and I’ll get your sticker sent over as soon as I can.