♨️Have you ever heard of the concept of non-equilibrium in #thermodynamics?
🎙️New #SciLux#podcast episode is out! Listen to Prof. Massimiliano Esposito from the University of #Luxembourg
& Dr Emanuele Penocchio, postdoc researcher at the Northwestern University
@CCochard@jaztrophysicist Attention, il est tout-à-fait possible que la somme de deux formes différentielles non-exactes soit exacte : les formes exactes forment un sous-espace vectoriel, pas son complémentaire ! Je soupçonne donc qu'en général ni δW ni δQ ne sont exactes, mais qu'il se trouve que leur somme l'est.
@CCochard@jaztrophysicist Ça typiquement je ne comprends pas ce que ça veut dire. C'est peut-être ce que disait mon prof de physique et qui me laissait comme deux ronds de flan, je ne sais pas interpréter.
A question for chemists. Does anyone know of someone in the UK who does iondinolytic titration calorimetry? Or some similar reaction #calorimetry technique that can be done to measure thermodynamic stability? #chemistry#thermodynamics#hess#thermochemistry
My friend Will said the most awesome thing on IRC:
"Quantum theory says information can't be destroyed. Thermodynamics says lol yeah but we can blender it into so many pieces you can't put it back together with magnets and duct tape." #quote#thermodynamics#science!
Why do we say that batteries/energy storage is something that stores and releases energy?
A device that is able to convert some amount of heat into zero-entropy energy is ~just as useful as a battery of the same capacity. It's obvious that such a device can exist (a thermos with some amount of heat capacity inside at a temperature lower than environment + a heat engine is such a device), and it has at least one significant advantage over a battery: it is not necessarily able to release a significant quantity of energy on failure/destruction.
One can easily create such batteries in that exact way (by using a thermos and heat engine). My rough upper bound is that the highest "energy" density one could get without phase transition would be ~2MJ/kg[*] (by using gaseous hydrogen as the medium), which is a bit better than current batteries (but is an upper bound that ignores any practicalities of handling hydrogen, inefficiencies other than thermodynamically necessary, and the weight of infrastructure). I've looked at a few phase transitions (e.g. ice/water or liquid/gaseous nitrogen) and they don't seem to be able to give anything even close to the value for hydrogen (or, for that matter, mere Li-Ion batteries).
Are there other ways to store negative entropy? I imagine that chemical ones "should" exist, but I have terrible intuition for entropy changes across chemical reactions to even know where to start looking.
[*] I've taken half of the energy that would be needed to heat hydrogen from ~0K to ~room temp (half because efficiency will change linearly between 1 and 0 as the temperature of the hydrogen increases).
tl;dr Are there any better ways to store negative entropy without storing energy than storing very cold hydrogen? Is there some sort of fundamental limitation in play?
We think of #AirConditioning as a way to cool things, but it actually produces three sources of warming on the outside of whatever you're trying to cool:
it's a heat pump, transferring thermal energy from whatever you're cooling, to the outside
there's waste heat from the operation of the machine, and
if the AC is powered by energy derived from fossil fuels, the generation of that energy increases greenhouse gases in the atmosphere and thus exacerbates global warming.
h/t to a post on #Lemmy that made me think about this and iron it out in my head
This isn't to say don't use it at all, but it does mean that it's prudent to think about how we can use less of it, because using it literally contributes to making the surroundings hotter.
Je vais commencer à enseigner en thermochimie à la rentrée (dans 1 mois grosso modo...😟), je ne suis pas chimiste et ne comprends pas toutes les notes du collègue précédent et tout le monde est en vacances...
Est-ce que vous auriez un conseil sur la bible de la thermochimie ? (si possible en français pour que je me familiarise avec le vocabulaire)
Normally we don't hear planes taking off more than a couple of times a day at home, when we're outside. Today I heard a tonne of them, it's not because of the prevailing winds, I think, rather that it's hot so pilots have to put the pedal to the metal to get off the ground. I'm sure this isn't good for CO2 emissions, which are already catastrophic. Carnot was a very smart chap!
@NormanDunbar I have a similar story from trying to get home from Mumbai. Except they offloaded me and my luggage, got home a few days later. The joys of traveling standby as the family of an airline employee, mostly it was fantastic though.
@fractalkitty That's great! I've seen that behavior many times and figured that's what they were doing, but I've never read of it. I love that splooting is the technical term.😆
I need to look into re-learning #thermodynamics. #Motherboard says the #CPU#core#temps are around 10C higher than what the #heatsinks are (I built my own #sensor set for this machine - because I wanted to.)
Granted, this is one of the old E5-2600v2 series #motherboards in the computer I'm typing on right now.. (different computer, not the server - waiting for #Amazon to deliver my new #frelling CPU coolers), an X9DRH-7TF by SuperMicro, so maybe that's #normal?
Yeah, I know, WAY overkill for a #workstation, but it's also a #pull from a previous #server iteration, so...
Yes, I'm #weird. I upgrade my #servers, then my #workstations get all the old #parts.
@ssb The job of the cooler is to transport heat from the package surface to the surrounding air at the same rate it is produced by the chip. For simplicity, CPU spec sheets quote the thermal design power (TDP) which must be met by the cooler. Heat flows from hot to cold, so the CPU die will always be the warmest and the ambient air the coldest.
Paul Sen’s book Einstein’s Fridge, on the history of thermodynamics, is brilliant and fascinating and full of insight. This is possibly my favourite new snippet of information, appropriately enough from the final chapter on information thery and how the study of computer bits relates to thermodynamics.
“An E coli uses 10,000 times less energy to process a bit of information than the transistors used in most human-built information processing devices”
@helenczerski Thanks to you and @sellathechemist for the recommendation, based on which I’ve just read it. It is indeed brilliant. Clear explanations. Fascinating to know more about the people whose names are familiar from various laws, and to understand how their interactions personally and through the forum of scientific literature led to our state of knowledge.
J'adore :shibahearteyes:
Donc il utilise l'entropie en physique pour aligner sa pile d'assiettes ! 👌
(Les objets recherchent toujours un état d'énergie minimum selon la 1ère et 2ème loi de la thermodynamique : conservation de l'énergie et augmentation de l'entropie) #physics#physique#thermodynamique#entropy#entropie#thermodynamics