Talk:Phase-change material

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Discussion[edit]

In the table, Na₂SiO₃ $\cdot$ 5H₂O is listed as having a melting point of 48^oC, but its melting point is actually 72^oC. Na₂SiO₃ $\cdot$ 9H₂O, on the other hand does melt at 48^oC. I would change it, 76.120.179.248 (talk) 00:31, 6 July 2009 (UTC)[reply]

I second the above note, and I edited the table to change the value from 48 to 72. My information is from http://www.minsocam.org/ammin/AM18/AM18_206.pdf which is apparently an article from the journal of the mineralogical society of america, but I can't figure out year, volume, etc. The article does include the melting points of some other sodium silicate hydrates. In fact, the nonahydrate has the originally-stated melting point of 48C, so I'm worried that the other thermodynamic data is about the nonahydrate too, which would mean that the table is still wrong! Sorry I don't have more time to spend on this right now. I actually owe the authors a debt of gratitude since I needed something to absorb heat at around 40C and found Lauric acid and sodium silicate nonahydrate via this page. The former works ok (could use a little more energy capacity) and the latter is in the mail.Supernatent (talk) 21:09, 3 October 2012 (UTC)[reply]

Surely the most comonly used phase change material is ice, not "most commonly used PCMs are salt hydrates"; particularly since ice is now reasonably commonly used in building air handling to both shift load (cooler at night, power is cheaper) and reduce the size required for the chillers.

Meanwhile, as illustrated here some wonderful edge cases in PCM usage; for example microencapsulated and use as a coating in clothing

Bhyde 16:55, 28 October 2007 (UTC)[reply]

The article says: "They store 5 to 14 times more heat per unit volume". I am not sure where this comes from. The specific heat capacity of water is 4.18J/gK and these material have a requires roughly 200-300J/g to melt, I think the value should be maybe 50-80 times that of water (need correction for density though), if, you are interested in storing energy at the melting point of the material. —Preceding unsigned comment added by 130.243.250.89 (talk) 20:31, 1 January 2009 (UTC)[reply]

If you read the reference, you will see that the value is indeed correct. MTessier (talk) 02:20, 5 November 2012 (UTC)[reply]

Sodium acetate[edit]

Why doesn't Sodium Acetate appear in the table of properrties, when it features in the illustration for the introduction of the article? According to the (linked from the illustration caption) article on Sodium Acetate, the trihydride has "... latent heat of fusion is about 264–289 kJ/kg." I would add this and other data from that article, but maybe there is a reason that it isn't mentioned. 101.117.138.24 (talk) 08:36, 13 July 2014 (UTC)[reply]

Material Tables[edit]

The main tables on this page have a vast number of entries regarding different PCMs. For the table on Thermophysical properties of common PCMs the majority of these have been pulled from one research paper and a workshop ppt, whilst an impressive number of materials has been collected the details are very sparse. For about 80% of the materials only their latent heat values are listed - this is not sufficient information to compare - other physical properties such as the densities of the material are needed.

Would it not be more useful to have a short table, citing examples of different PCMs (eutectic, organic, inorganic) that are in use?

I have similar comments about the second large table in the article. There is a lot of information which isn't useful and it reads like a condensed catalogue. It might just be worth while having a single table listing common examples from literature than everything these specific manufacturers can produce. — Preceding unsigned comment added by PaulRPG (talk • contribs) 20:42, 4 August 2015 (UTC)[reply]

Is it possible to add a separate scroll bar to the long tables so that a reader may skip to the rest of the article?Circuitboardsushi (talk) 09:29, 9 July 2019 (UTC)[reply]

Thermal Composites[edit]

"They are also meant to discover minor elements in the earth." WTF does that even mean? 99.239.74.134 (talk) 11:36, 23 June 2016 (UTC)[reply]

What about solid-solid phase transitions?[edit]

Can't those (polymorph, allotrope or polyamorph changes) be endothermic? — Preceding unsigned comment added by Dqeswn (talk • contribs) 17:32, 19 November 2016 (UTC)[reply]

Other material classes[edit]

In addition to the solid-solid comment above, there are quite a few other material classes in the standard list of PCMs. this includes both low and high temperature metallics (the table even lists a number of pure metals), salts (not hydrates), other organics like carboxylic acids and clathrate hydrates. The solid states include the some pure organics, organic salts, organometallics, and recently has included solid-state (martensitic transformation) metals like NiTi shape memory alloys. — Preceding unsigned comment added by Nrjank (talk • contribs) 00:14, 2 November 2020 (UTC)[reply]

comparison to masonry (heat storage)[edit]

This is technically mostly correct, but the mass of available masonry is orders of magnitude greater than that of PCM and it fulfils its load-bearing properties at the same time. In other words: Comparing ~1kg/m² of PCM with ~200 kg/m² wall (per area of wall that is) is somewhat more usefull, all of the sudden masonry isnt so bad. Considering a temperature-swing from 20 to 30 °C over a year would also drastically change the result. But sure, if I define a infinitesimal difference around the transition of the PCM the factor goes to infinity - woohooo! But first defining a range of 10°C and then calculating big numbers with only 1°C or 4°C temperature swing is absurd. Also, if "an exact temperature is required", as said above, the factor would go to inifity (eg. 0,01°C around the phase transition = full 200 kJ/kg latent heat vs. only 0.01 kJ/kg for the masonry = factor 20'000 "better"). Therefore I will change this section a bit. --Eheran (talk) 07:55, 8 December 2020 (UTC)[reply]

Within the human comfort range between 20–30 °C, some PCMs are very effective, storing over 200 kJ/kg of latent heat, as against a specific heat capacity of around one kJ/kg.°C (that is per degree Celsius) for masonry. The storage density can therefore be 200 times greater or more than masonry per kg if an exact temperature is required. If a temperature variance of, say, 4°C can be allowed, the density is 50 times greater. [2]

Nano Enhanced Phase change Materials (NePCM)[edit]

Dispersing thermally conductive nanostructures is an effective method to improve the thermal performance of phase change materials (PCMs). For this purpose, nanocarbons, nanometals, and nano metal oxides have been used to develop nano-enhanced phase change materials (NePCMs) with unique thermal properties. In 2007, Khodadadi and Hosseinizadeh firstly reported on the accelerated freezing process of water enhanced by Cu nanoparticles. They reported that the freezing time of water was shortened from 3000 s to 1400 s by dispersing 20 vol.% of nanocopper. After that research, various aspects of NePCMs were investigated by other researchers. Triplex shell-and-tube systems filled with NePCM, adding porous copper foam to NePCM, the effect of cavity aspect ratio on NePCM are some of these field that have been investigated yet. — Preceding unsigned comment added by Adpn888 (talk • contribs) 10:59, 22 October 2021 (UTC)[reply]

Re-add the list of phase change materials[edit]

Should the list of common phase change materials be re-added? Not the list of every commercially available product but just the general common substances; such as water, salt, metals. The extended list was removed 11:33, 15 June 2022‎, and was a extensive removal edit. Thoughts on this anyone? 97.122.162.167 (talk) 15:09, 24 September 2023 (UTC)[reply]

Thanks, I've been searching the web for this the whole afternoon. At least I know now what version to look for.. No doubt the petrol mafia at work... Yes, please add it back in. 217.149.164.213 (talk) 15:38, 16 October 2023 (UTC)[reply]

You're welcome. I looked at the list years ago then came back for a reference and the whole list was missing. So I had to go find it. I'm glad that my trip down the rabbit hole helped. I do think that re-adding the common substances would add to the article but I still would like some discussions against or for. 71.218.83.204 (talk) 08:00, 21 November 2023 (UTC)[reply]