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[deleted] t1_j18hcby wrote

Reply to comment by incredibolox in Why do we use phase change refrigerants? by samskiter

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GenericUsername2056 t1_j18i7th wrote

>Mmm, not fusion. Fusion is a specific physical process that only occurs in stars and H bombs (so far). And not freezing. That's liquid to solid.

The latent heat of fusion is the amount of energy required for a substance to transition between its solid and its liquid state. Their terminology is correct.

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seven_tech t1_j18j4up wrote

I've literally never heard it called that. Enthalpy of fusion, yes. But not latent heat of fusion. Though it does appear it can be called that. Still referring to a process that doesn't happen in commercial refrigerators (solid-liquid or vice versa).

At uni here, latent heat refers to the amount of heat a substance can absorb before changing state. If you are talking about the heat absorbtion of a process (like state change) that's the 'heat of' or 'enthalpy of', not latent heat of. Not sure if maybe it's a difference of country thing.

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GenericUsername2056 t1_j18jqxb wrote

'Latent' comes from latin 'lying hidden', i.e. heat which does not result in a change in temperature, as opposed to sensible heat. 'Latent heat of fusion/(de)sublimation/melting/vaporisation' etc. are widely used terms. Just type in 'latent heat of fusion' in Google scholar to see for yourself.

The person you responded to made a mistake in the type of latent heat relevant here, but not in their use of 'fusion' to refer to a specific type of latent heat.

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seven_tech t1_j18l0vk wrote

Again, widely used where? We don't use them here in Australia. We use simply heat of or, more correctly and usually, enthalpy of. Latent heat is a property of a material to me (specific latent heat). We don't use latent heat to describe a process, because it's confusing vs the material property called specific latent heat. That's how we were taught in High school and Uni. In fact I remember a lecture our year 12 physics teacher gave about not using latent heat to describe a process, because of the confusion with the material property, so use enthalpy.

Also, we no longer use fusion to refer to melting. That's an old terminology that's being replaced as fusion has very specific meaning now in physics/chemistry since we discovered the process in the early 20th century. Fusion meaning melting was coined well before this.

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whyisthesky t1_j18lsv9 wrote

Latent heat of fusion is widely used in the UK and US at university physics level

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seven_tech t1_j18mlkb wrote

It's not in Australian university physics. It would be enthalpy of desublimation crossed conversations-enthalpy of melting. I did high school physics and 2 years of physics at uni. I never once heard it called latent heat of or fusion.

Also, type fusion into Google. Which page number do you have to go to before you find it being referred to as the process of liquid to solid? It may have been used as a standard reference to that process. It isn't anymore, because fusion (the atomic process) was discovered.

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craigiest t1_j18otq8 wrote

Just because you haven’t experienced something or it isn’t a thing right around you doesn’t mean it isn’t common anywhere else. Jeez.

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whyisthesky t1_j18nksj wrote

I’ll see your 2 years at uni studying physics and raise you 4 years doing a masters in physics in the UK where the term is common.

It is a somewhat antiquated term, but it’s not alone in that in physics.

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seven_tech t1_j18ozp2 wrote

Again, not saying it isn't used anywhere. It isn't used here anymore. Because it's no longer specific.

We use enthalpy instead of latent heat, and we use desublimation instead of fusion. Because latent heat is also a material property and fusion is an atomic process.

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kagamiseki t1_j18ya45 wrote

"fusion" is not "latent heat of fusion"

That's like saying hot dog isn't a valid term that means an American style sausage in a bun, because look what comes up on Google when you search "dog".

Of course if you search a different term, or only part of a term, you will get a different result.

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seven_tech t1_j1aozpx wrote

Mmm, I get what you're saying, but I don't agree.

  1. Fusion is a word to describes a process, in both cases. It's not a noun made up of multiple words like hot dog. And 2) Science terms in the 21st century are coined to be unambiguous. That's the point of defining something in science.

If we want to get technical, it's nuclear fusion. But that still leaves the idea you could be discussing 'nuclear' melting, which is again, ambiguous. Science doesn't like ambiguity.

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GenericUsername2056 t1_j18lwsl wrote

>Again, widely used where?

Internationally. The exact same term is used for instance by Y. Cengel in his textbook Thermodynamics: An Engineering Approach, which is a very popular book on engineering thermodynamics for university-level courses on this topic. This terminology continues to be used to this day by a plethora of researchers. If you don't believe me, again, just search for the term 'latent heat of fusion' on Google Scholar. This is an odd hill to want to die on.

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[deleted] t1_j18oltx wrote

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GenericUsername2056 t1_j18ov2h wrote

>(which, if you Google and read a bit, will confirm that calling desublimation, fusion is an old phrase that is being replaced).

>if you suddenly called desublimation, fusion. We've not used fusion to refer to desublimation since the 70s.

Now I know for sure you don't know what you're talking about because desublimation is the phase transition from a vapour directly to a solid, not from a solid to a liquid. I was listing several types of latent heats earlier, not synonyms as you must've erroneously assumed.

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Calvert4096 t1_j19fxxj wrote

People are jumping on your back a bit, but I never really liked the term myself exactly for the confusion reason you say.

If someone says "fusion" with no context or qualification I think nuclear fusion.

That said, "latent heat of fusion" doesn't have any ambiguity for me since high school, nor does it seem to for most of the English-speaking world. If they don't teach that in Australia... I guess they set you up to waste your time on conversations like this one.

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seven_tech t1_j1asa41 wrote

Haha, thanks. Yes, this was my whole point. I was never taught 'latent heat of fusion'. Nor were my colleagues. So we never had that ambiguity. Hence why I started the argument.

But hey, it's the internet. You'll get dragged for calling water wet...

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LionSuneater t1_j18yo9l wrote

Latent heat of fusion is a pretty common term in the US. I use it in our physics department and nobody bats an eye.

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seven_tech t1_j1apyhr wrote

Yes, I've had this argument several times.

We don't use that term in Australia. Because it's ambiguous. Fusion (more specifically nuclear fusion) is a specific physical process and its use in science is replacing fusion as in 'melting', which is a term dating back several hundred years. So we use melting now, because it's unambiguous otherwise.

You could argue, and many people would still agree, gay means happy. Yet you also wouldn't be unsurprised if people thought they were homosexual if you said 'I thought he was very gay' and many young people would never have heard gay used in any other context. Language changes and it's ambiguous. And science when speaking of fusion, doesn't like ambiguity.

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Lookheswearingabelt t1_j190ikq wrote

Latent heat of fusion (solid to liquid) and latent heat of evaporation (liquid to gas) are common terms here in Canada as well

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user31415926535 t1_j18ie2a wrote

>heat of fusion

"fusion" just means "melting" in this case, changing state from solid to liquid.

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seven_tech t1_j18jtxf wrote

Yes, I've never heard it called that, though the internet says it's a thing. At Uni here, it's called enthalpy of phase transition (or enthalpy of melting). Fusion is only the literal atomic process of fusing 2 atoms. I have a feeling heat of fusion is a very antiquated version that's being replaced, because fusion has such a specific chemical meaning. Sublimation, evaporation, melting and condensation are the only phase change phrases we have ever referred to at Uni.

But also, still not relevant here. Almost all commercial (and most industrial) refrigeration uses gas and liquid, not solid and liquid.

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