Talk:List of thermal conductivities
|WikiProject Physics||(Rated List-class, Low-importance)|
The condition of this list has previously been discussed in Talk:Thermal conductivity#Example values for common elements OK?. It got some work done, but I think I need to be more specific:
- The Electrical Conductivity column, which is more acceptable on a page dedicated to this list, has far too many expressions for the same unit.
Some materials have their composition described in the Material column, which makes that column hard to scan -- this information could go in the notes. Some material compositions link to oxides rather than the elements, which suggests something different from what the text itself says.
- The reference superscripts make the table a burden to read, and the way they've been used inconsistently between the conductivity and temperature columns makes them unhelpful.
Also, in an ideal world, the temperature would be specified once, and all materials would be measured at that temperature. Specifying two ranges isn't at all clear, most particularly when the references for the ranges aren't consistent with the references for the conductivities. This problem has stopped me from making a separate Reference column to clarify the table. --ToobMug 13:55, 10 February 2007 (UTC)
Regarding the reference superscripts: Perhaps they should be moved to the end of the numbers, e.g. 12345g instead of g12345. The table does not sort properly if they are written with preceding superscripts. I will make this change and if I am violating some wikipedia rule, please let me know here and revert it. 188.8.131.52 (talk) 18:49, 7 February 2008 (UTC)
Request for data
First, a vacuum should be included for reference.
As far as I know, vacuum does not conduct heat, although it can transfer it by radiation. Platinum should be added for its use in temperature measurements. YBCO would be a nice (but challanging) addition. —Preceding unsigned comment added by 184.108.40.206 (talk) 01:38, 18 July 2010 (UTC)
- Heat transfer through the vacuum does not conform to Fourier's law. For most materials, energy flux between two planes is proportional to cross section and inversely proportional to the distance between the plates (hence the thermal conductivity coefficient has m^-1 in the dimensionality). The flux between two close parallel planes in the vacuum is not related to the distance between them (to the first order). Instead it is governed by Stefan-Boltzmann law, . At room temperature, , where c = 5.7 W/(m^2 K). --Itinerant1 (talk) 22:05, 4 August 2012 (UTC)
- I couldn't avoid the vacuum. Apart from that and with respect to the thermal conductivity of platinum I had the impression that the way that a platinum resistance thermometer became any good is more involved with the electrical resistance of a platinum wire as a function of its temperature. Isn't that how it works?Patriot1423 (talk) 05:06, 14 April 2016 (UTC)
Some of the temperatures cited in the properties table are negative(in kelvin), that has to be a mistake clearly. someone should take a look at it. — Preceding unsigned comment added by 220.127.116.11 (talk) 16:32, 30 August 2013 (UTC)
- I always thought that those Kelvins were separated by hyphens. Since they also resemble a negative sign I suppose that they should probably be replaced with commas. Anyone else think so?Patriot1423 (talk) 05:06, 14 April 2016 (UTC)
Thermal Conductivity Common Liquids
Common fluids and their thermal conductivity
Thermal Conductivity of some common liquids at a temperature of 300 K Fluid Thermal Conductivity (W/m K) Acetic acid 0.193 Acetone 0.180 Alcohol, ethyl (ethanol) 0.171 Alcohol, methyl (methanol) 0.202 Alcohol, propyl 0.161 Ammonia, saturated 0.507 Aniline 0.172 Benzene 0.167 n-Butyl alcohol 0.167 Carbon Disulfide 0.161 Carbon Tetrachloride 0.104 Castor Oil 0.180 Chloroform 0.129 Decane 0.147 Dodecane 0.140 Engine Oil, unused 0.145 Ether 0.130 Ethyl acetate 0.137 Ethylene Glycol 0.258 Freon refrigerant R-11 0.093 Freon refrigerant R-12 0.071 Glycerine 0.285 n-Heptane 0.140 Hexane 0.124 Isobutyl alcohol 0.134 Kerosene 0.145 Methyl alcohol 0.212 n-Octane 0.147 n-Pentane 0.136 Phenol 0.190 Propylene glycol 0.147 Transformer oil 0.110 Toluene 0.151 Turpentine 0.128 Water, Fresh 0.609
Problem with the ordering
There seems to be some problem when ordering by Thermal conductivity. When trying to order from least to most conductor the Polyethylene foam goes nearly the end of the list where it should be at the start. I have tried formating the values differently but it doesn't seem to have helped. —Preceding unsigned comment added by 18.104.22.168 (talk) 12:06, 21 October 2010 (UTC)
Clean up idea
- Not that it matters two years after the comment, but: I am pretty sure silver is a better electrical conductor (though a much more expensive one), and electrical and heat conductivities in metals have a roughly constant ratio. So I do not think the references are wrong in that respect. Tigraan (talk) 11:54, 13 April 2016 (UTC)
- Well thank you very much Tigraan and I don't know about the Wiedemann-Franz law but what I had told the unnamed user is that if the estimates are correct then there are some temperatures where a high purity copper is more conductive than silver and others where silver is the better conductor. Also I just checked and I noticed that I spelled it out far enough to get that into the list though it is detailed a lot finer in the cited Data Series itself. It used to be right in the CRC Handbook (where it is a lot easier to read it).CheersPatriot1423 (talk) 05:06, 14 April 2016 (UTC)
- Greetings Mike. You certainly have a point and what I did to the list makes it totally unwieldy. For many purposes the pat list above would be much more practical. But I was concerned about the authority of the measurements. I noticed wide discrepancies in various reports. For example the Yarwood and Castle tables from the University Press at Glascow have the thermal conductivity of quartz posted at 9.2 W m-1 K-1 at 291 Kelvins and the only way that that lines up much is that no one knows what it means. Also if you look up the details in the TPRC Data Series you find that many noted scientists have been reporting various thermal conductivities all over the map. If no thermal conductivities had really been measured then all tales about heat capacities would seem to be more of the same. Etc. and all of this would seem to be no good for the first law of thermodynamics and no good for the reputation of the enlightenment.
- If maybe to the contrary the charges are untrue then I would think that probably a good investigation would find out whether the apparent discrepancies are really discrepancies. For example and quite apart from any consideration for any alloys it is possible to find widely different tales about the thermal conductivity of pure aluminum at very low temperatures. They are now posted in the table. For example at 5 Kelvins the TPRC estimate is nearly five times as high as the known facts as they are found in the CRC Handbook. And this kind of business could lead you to wonder whether maybe the science building has been more interested in its 401K Plan then it was in any thermal conductivities?
- But then it you nose around close enough to make sure then eventually you find that pure silver did not mean the same thing to Weast as it did to Touloukian and Powell. And I would have thought that CRC purities were quite picky already! One little bitty bitty amount of dirt in the aluminum and it makes a very big difference at very low temperatures? Evidently. And I find that surprising. In any case it would seem that all of this business would look a lot more reliable if you find independent authorities in any close agreement on it and now in the table we find American and Soviet estimates in close agreement in the 1970s. Of course if the history of this business was supposed to be no ones business then prudent people would assume that maybe what it really means is a 401 K Plan and not any thermal conductivities at all and it happens that the widely accepted values have been holding up pretty well now for more than four decades anyway. At this point that is documented.Patriot1423 (talk) 04:52, 20 April 2016 (UTC)
Reference no. 7 just links to Hukseflux sensors. I assume Hukseflux once published a table containing thermal conductivity values of different materials. This information is no longer accessible and the link to Hukseflux looks more like product advertisement. — Preceding unsigned comment added by 22.214.171.124 (talk) 16:02, 1 December 2014 (UTC)
Quality of the data
A rough check on the data show a rather heavy leaning on web sources like engineeringtoolbox, which are not of sufficent quality. Many references are to comercial sites. This compromises the whole article, although it probably deserves much better! I can imagine score of students making rather msitaken calculations on the basis of these data. Not necessarily life-threatening, but worrysome! The only reliable sources of data are from academic origin in such a context. There is no possible compromising with physics and thermodynamics! Unfortnately, I can' t pick up the job of checking everything. Cicero — Preceding unsigned comment added by QuousqueCatilina (talk • contribs) 09:46, 8 August 2015 (UTC)
- I would tend to think that for example a Wernher von Braun would probably be a qualified person even if he had never graduated from nursery school.
- Also such a character seems to be a bit unlikely by comparison with people who have diplomas from places that would get sent to the welfare department if they tried to compete with those who would always put the rustiest part of the plumbing in the darkest corner of the basement.
- And oh good good and off to the welfare department and surely it is people who are being bad for the economy who are most qualified on thermal conductivities, right?
- And not Donald Trump, right?
- And if that were the question at hand then maybe we would be very close to agreement.
- But did you mean to suggest that good authorities are good enough?
- To the contrary experience would lead me to think that it takes independent authorities.Patriot1423 (talk) 06:41, 14 April 2016 (UTC)
A Recent Objection
An anonymous engineer recently posted this objection on the user page of Patriot 1423:
Dear Patriot1423 - I sincerely do not wish to deface your page but I want to send you a private message and cannot find a way to do it (clicking your name or talk leads to just editing your page, which is not that I want to do, however this system is very unintuitive). Anyway please delete this after you read it:
You have been editing the page "list of thermal conductivities" extensively over the past months, and in the process you have destroyed its most important function - which is to provide a scientifically-correct ordered list of average thermal conductivity values (for various elements and materials) in W/m.K. By listing multiple values for each item you've basically just made the table useless, it's completely unnecessary to do this and hugely detracts from the benefit of the table, since there are now hugely irrelevant fringe values padding out each box. As you can probably tell I am no wikipedia guru, but I am an engineer, and I find this page a useful resource. Please return it to its previous guise which was working sufficiently, and is viewable here: https://en.wikipedia.org/w/index.php?title=List_of_thermal_conductivities&oldid=703545180
Apart from listing many superfluous values in each box for thermal conductivity, you have completely broken the ordering system (which can be used by clicking the little up and down arrows - i.e. ascending and descending) of thermal conductivity. When descending (i.e. arrows clicked twice), the order should start with helium, graphene, etc, which are above diamond, which is above copper... it's the natural and correct order. With whatever you've done with the multiple values, it's confusing, and also breaks the correct conductivity order. The page was fine as it was, maybe just leave it be unless you are intimately aware of what you are actually editing. Thanks and please don't take any offence, it just hurts me to see a useful page destroyed. Sincerely - an avid user of wikipedia - however not an editor (as you can see).
— Preceding unsigned comment added by 126.96.36.199 (talk) 06:11, 22 April 2016 (UTC)
I copy my response and invite a dialogue:
- Hello Engineer:
- I hesitate to delete your important message so fast, as you have requested, since you have important objections.
- I’m not so sure that the old list is sufficient since the thermal conductivities actually get around a lot over some large temperature intervals.
- Would you measure your refractory insulation at only one temperature and then build a blast furnace with it? If so then I would get nervous about the safety of everyone who is going to work there over close to a whole bunch of molten iron!!!
- Also I have noticed that the theoretical article on thermal conductivity has a bunch of theoretical stuff which could hardly get evaluated either one way or the other if we pay no attention to the facts.
- I don’t want to throw away a simplified version and instead I would have thought that simplifications are the second part of it.
- Now I’m going to copy your message and put it over in the talk section of the article where I am not the only one who has been concerned about the quality of the data. Also I will copy my response over there and so far my impression is that probably Wikipedia deserves more than one list of thermal conductivities.
- Thank you for your comment and this matter has not yet been settled.Patriot1423 (talk) 09:31, 22 April 2016 (UTC)
- @Patriot1423: I agree with the user above, the table in its current state is much more challenging to read than is necessary.
- In my opinion the page would benefit significantly from being split into a table of conductivities at room temperature (where most users will be interested in values for) and at various temperatures (for those wishing to use wikipedia as a resource). Testem (talk) 23:58, 28 September 2016 (UTC)
- @Testem: I fully agree both sides are right and the page should be revised to include one sortable table for conductivities at room temperature and one more difficult table for conductivities as a variable function of temperature (to the inclusion of unusual temperatures).
- I'm not sure if I will find time for that...Patriot1423 (talk) 21:14, 10 October 2016 (UTC)
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