Timeline for Can you model cold as flowing?
Current License: CC BY-SA 4.0
11 events
| when toggle format | what | by | license | comment | |
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| Aug 26, 2022 at 4:54 | comment | added | Chemomechanics | @JMac I don't disagree. My favorite heat transfer textbook doesn't mention entropy once. I just thought it would be interesting to discuss the threshold where the "flip the sign" strategy goes wrong. | |
| Aug 26, 2022 at 0:09 | comment | added | JMac | This answer talks a lot about entropy, but I'm struggling to see how entropy actually plays in to the heat transfer analysis, besides creating the underlying rules (like heat transfers between higher temperature and lower temperature). In a system where you're looking at producing some sort of work from the heat transfer, the entropy would be relevant; but it's not like OP is asking how much mechanical work they can get out of the melting cube. | |
| Aug 24, 2022 at 15:59 | history | edited | Chemomechanics | CC BY-SA 4.0 |
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| Aug 24, 2022 at 15:55 | comment | added | Chemomechanics | I've edited my answer to more clearly address this point. | |
| Aug 24, 2022 at 15:54 | history | edited | Chemomechanics | CC BY-SA 4.0 |
added 1093 characters in body
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| Aug 24, 2022 at 14:22 | comment | added | Tyler M | @Chemomechanics I'm still not following here. Entropy is just the lack of useful energy; entropy should still go up, whether you're watching the "heat flow" or the "cold flow". That should be a constant. Your equation would just be "add a minus sign" for the entropy; entropy wouldn't "be negative". Could you elaborate? | |
| Aug 24, 2022 at 1:18 | comment | added | Philip Couling | Thanks that helps | |
| Aug 24, 2022 at 1:14 | comment | added | Chemomechanics | @PhilipCouling That's not correct; if you heat an object, entropy transfer occurs into the object, not the other way around. (Entropy is also generated where energy flows down the temperature gradient.) This is the inequality of Clausius. | |
| Aug 24, 2022 at 1:11 | comment | added | Philip Couling | Could you clarify (or elaborate) on the need to "define a negative entropy". To the casual reader plain old "entropy" already moves in the right direction; starting at the placement of the ice cube and moving outwards, just as much as it would if you placed something hot at the center? | |
| Aug 23, 2022 at 22:41 | comment | added | Criticize SE actions means ban | I'm sure I've read somewhere that "living organisms consume negative entropy" | |
| Aug 22, 2022 at 19:41 | history | answered | Chemomechanics | CC BY-SA 4.0 |