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Titanium Heat Transfer Left To Right
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- This topic has 30 replies, 12 voices, and was last updated 6 years, 1 month ago by Jerry Adams.
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Jan 19, 2018 at 3:58 pm #3513251
I came across this information at the Keith site:
Do you agree with their statement?
Jan 19, 2018 at 4:30 pm #3513257thermal conductivity W/mK – https://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html
aluminum 204
copper 386
titanium 19 – 23
so heat is transferred much more slowly in Titanium because it has low thermal conductivity
doesn’t make much difference that it’s thin though. Like they said, since it’s thin the heat will quickly get all the way through from outside to core to inside, but then, sideways it doesn’t make much difference how thin it is. If you have water inside a pan, it will keep the inside surface of the Ti cooler. If the Ti was thicker, more heat would conduct sideways, inside the Ti and on the outer surface, so the heat would spread out sideways more
Jan 19, 2018 at 7:46 pm #3513291That “… heat will travel left to right very slowly…” is an interesting concept for both heating and cooling. I’m looking forward to the upcomming innovations.
Jan 19, 2018 at 8:27 pm #3513298But, the heat will transfer from left to right very slowly which will in turn keep the handle temperatures very low
Wow, that sounds like a load of marketing crap trying to justify cool handles on titanium due to material properties. Forget about the fact that hot air flows up the sides of the mug/pot.
Jan 19, 2018 at 11:41 pm #3513329I disagree with the grammar and spelling in that statement.
Much of what they are trying to say is true. Ti conducts heat (per unit of cross section) much less than aluminum and in the same range as SS, but Ti pots are thinner, so, yes, they conduct less heat to the side.
Adding to Jerry’s data:
aluminum 204
stainless steel 12 to 45
titanium 19 to 23
My cast iron (thermal conductivity = 47 to 80) fry pan conducts heat to its handle more slowly than my similarly thick aluminum pots (conductivity = 200). But as Jon points out, hot gases from the flame typically are also heating the handle directly which can dominate over conduction from the pot. HX fins can help in that by extracting more of the heat from the flame (this also allows JetBoil to use a neoprene cosy that usually doesn’t melt). At home, and occasionally on the trail, I’ll put my pot a little off-center to keep the handles further from the flame and therefore cooler.
There’s another way an aluminum handle can seem “hotter” than SS or Ti. Because it’s more conductive, more heat is transferred into your hand when you touch it. This is VERY clear to me when I’m moving frozen fish in metal trays from a deep freezer. An aluminum pan feels A LOT colder to my hand than a steel one even though they are exactly the same temperature.
Never lick a flagpole in winter. But especially not an aluminum one. And definitely not a silver one (more conductive AND more heat capacity).
You’ve seen a demonstration of the reverse in those videos in which someone directs a flame onto a Space Shuttle insulating tile until it glows oranges and then picks it up in their bare hand. This principle is used all over Alaska in outhouses. Bare, low-density wood is a better toilet seat than painted wood or plastic. Carving one out of blue foam is ideal. Everything else is feeling cold, but where you contact the foam almost immediately feels warm.
Jan 20, 2018 at 1:17 am #3513345For those who prefer left-handled pots, I’ll sell you one that “teansfers” heat slowly from right to left for a nominal markup over retail.
:-)
— Rex
Jan 20, 2018 at 3:36 am #3513361For those who prefer left-handled pots, I’ll sell you one that “teansfers” heat slowly from right to left for a nominal markup over retail.
I hear they sell those in Israel…
Jan 20, 2018 at 6:20 am #3513375I’ve never run a titanium pot dry but seem to get the discoloration on the bottom but never reaches up toward the side/edge.
Jan 20, 2018 at 7:18 am #3513379The color change is due to heat anodization of Ti, it starts to forma at temperatures above about 550 F.
Jan 20, 2018 at 10:43 am #3513386Interesting Chinglish, but the core of what they are TRYING to say is correct, as David noted.
Cheers
Jan 20, 2018 at 1:55 pm #3513392Jon, once the water starts to boil and I let it boil for 15 min. does the Ti continue to heat up to that temp of about 550. My pot has never boiled dry and yet there is discoloration as if had been heated when dry. the color is not intense but it’s discolored. Is this an indication of what is being said by Keith? Heat is staying central on the bottom of the pot?
Another interesting thing to note is what Keith says about “scaling” having an effect on thermal transfer/resistance.
Jan 20, 2018 at 2:38 pm #3513395My WAG is that with a 3500° F flame on the outside and the leidenfrost effect on the inside the inner surface could reach “discoloration” temperatures.
Jan 20, 2018 at 7:14 pm #3513431Thank you Greg, thank you very much :-) I went to the link and there it was, clear as ever:
This is because at temperatures above the Leidenfrost point, the bottom part of the water droplet vaporizes immediately on contact with the hot plate. The resulting gas suspends the rest of the water droplet just above it, preventing any further direct contact between the liquid water and the hot plate. As steam has much poorer thermal conductivity, further heat transfer between the pan and the droplet is slowed down dramatically.
Jan 20, 2018 at 7:35 pm #3513432Quote from wickopedia.
“Like aluminium and magnesium, titanium metal and its alloys oxidize immediately upon exposure to air. Titanium readily reacts with oxygen at 1,200 °C (2,190 °F) in air, and at 610 °C (1,130 °F) in pure oxygen, forming titanium dioxide.[11] It is, however, slow to react with water and air at ambient temperatures because it forms a passive oxide coating that protects the bulk metal from further oxidation.[6] When it first forms, this protective layer is only 1–2 nm thick but continues to grow slowly; reaching a thickness of 25 nm in four years.[17]”https://corrosion-doctors.org/MatSelect/corrtitanium.htm
Note the section under salt water corrosion.If scaling or “scaled” means corroded, this statement is false. Titanium does indeed corrode and continue to corrode for several years after manufacture. Raw titanium is usually whitish metallic in color. It is often dyed by different colors in different dye baths. Blue is commonly found in most water. I won’t go any further but I would say, logically, if any part of a statement is false, it all is.
Jan 21, 2018 at 12:47 am #3513462If scaling or “scaled” means corroded, this statement is false.
China says: It means mineral deposition caused by use of “hard” water.
Jan 21, 2018 at 4:14 am #3513485Dan, I have less trouble with hard water scaling using Al than Ti. In either case, the statement is clearly false. I boil water for breakfast then pour the rest in my water bottle (with some coffee, of course.) Then I wipe it down with my food bandana. The Al always seems to shine a bit after doing that. And my bandana gets blackish from the aluminum. Ti simply builds up the typical blue stain/corrosion that does not wipe off.
Excerpt from “Dictionary” doing a google search:
a white deposit formed in a kettle, boiler, etc., by the evaporation of water containing lime.
synonyms: buildup, deposit, incrustation
“how can I remove the scale from my tea kettle?”
tartar formed on teeth.
a coating of oxide formed on heated metal.It can mean either corrosion or deposition. Aluminum and titanium both oxidize nearly instantly in the presence of oxygen. This coating is what you boil water with, actually. The trouble is, Titanium dioxide is white or bluish or yellow/orange on the surface of ti pots we use. Mostly the refraction pattern of the light on the TiO2 crystals, ie, which angle the corrosion/scaling was deposited at, and, the angle of the viewer. Anyway, it is fairly hard and not easily removed from Ti by rubbing (either with a bandana or steel wool. It *can* be removed with carbide sandpaper though, and, incidentally making the pot easier to clean in the future by polishing it.)
You can view more here: https://s3.amazonaws.com/academia.edu.documents/46415282/Interference_colors_of_thin_oxide_layers20160612-12317-hxvs79.pdf?AWSAccessKeyId=AKIAIWOWYYGZ2Y53UL3A&Expires=1516506282&Signature=A8NBsZzsV9iUv8l%2B%2F1Dmy2nNeK4%3D&response-content-disposition=inline%3B%20filename%3DInterference_colors_of_thin_oxide_layers.pdf
Though this was done with rather pure phosphoric acid and sulfuric acid (two different processes) it is certainly possible to find these as traces/substitutes in the water we drink, especially out hiking. For example, tannic acid can be found in woodland streams that has basically the same effect before it breaks down. The resulting “rainbow” patterns we see on Ti pots are actually the result of various layers of corrosion and the angle between the semicrystalline layers. So it appears to “move” with the angle of the viewer. The diffraction patterns cause some polarization and refraction between layers. But, you probably already knew that from high school physics.
Anyway, …
1) Ti is not necessarily the thinnest of all metal ware. I disagree with the first statement. Aluminum foil makes fine cookware out camping and is thinner.
2) The second statement doesn’t make sense whether from “deposition” or “corrosion.” Over a week of use, Al cleans much easier than Ti and “scaled” is removed every time it is dried. “Scaled” stays on the Ti.
3) The third statement has two parts “Heating from the bottom to the core” doesn’t happen any faster than heating side to side. Same material, same heat conduction. Conduction goes in all directions in a metal pan. Actually, side heating is of a benefit because it allows more even heating of the contents of a pot by reducing the high heat in the center spot to a lower, more diffuse heat. Sort’a like averaging out the heat. This means Al doesn’t stick and burn foods (again, making it easier to clean.) Spot heating is what you get from ti. Heat penetrates very locally. Try putting an 1/8″ of water in a 5″ wide pot and boiling it from the center (hot)spot. You will find there is not enough circulation in the water to bring the edges to a boil, it will be 10-50F degrees less than boiling at the outer edges. Thus extra time during boiling is needed because it is *not* evenly heated. This takes more fuel because 1) the center is steaming away water vapour longer than the edges take to boil. 2) Or, a higher flame (known to waste more heat) is needed to distribute the heat around to boil the edges.Who came up with this BS anyway?
Jan 21, 2018 at 6:12 pm #3513549That statement is awkward, but what they are trying to say sounds right.
I think their intention is to say “….heat will pass quickly through the bottom of a titanium pot to its contents because Ti is so thin, but heat will move slowly from side to side, because the conductivity is low, so handles will stay cool”.
Jan 21, 2018 at 6:58 pm #3513557Moral of the story: Don’t put the handles on the top or they will get hotter.
Jan 21, 2018 at 7:40 pm #3513569A moot point if the burner head creates a 3″ diameter flame that spreads along the bottom of the pot towards the edges.
Jan 22, 2018 at 3:40 am #3513635A lot of the heat will be lost an inch from the edges. Wasted heat is wasted fuel. On a three or four night outing, it doesn’t really matter. But out for a week or two (or longer) and you start paying in extra weight. For example, I use about 12-16gm/day, morning and night. So, a 230gm fuel canister will actually last two weeks with a small amount to spare. I would need another another 110gm plus the can (close to a half pound) if I wasted fuel at that rate.
Jan 22, 2018 at 9:07 pm #3513746You are not getting above the Leidenfrost point with a small cook stove…. but otherwise Greg is correct. The outer surface is touching the flames and getting hot. It is probably happening early on when you turn the stove on and natural convection cells haven’t been able to form inside the pot.
Jan 22, 2018 at 10:19 pm #3513761Something like the “Leidenfrost effect” is happening when the bottom of the pot is covered with bubbles, (think air layer) the size of the bubbles increase as the water gets hotter until there is the “rolling boil” at which time the bottom of the pot can become discolored the most. That is my take on the “Leidenfrost effect”
Jan 23, 2018 at 4:41 pm #3513892No that is not the Leidenfrost effect. That is the initiation of nucleate boiling which brings with it a rapid increase in the heat transfer coefficient (better cooling of the surface). Initiation of nucleate boiling often causes a slight drop in surface temperature because so much energy is being sucked up into vaporizing the water. The Leidenfrost effect happens when you are producing so much vapor it is unable to escape from the surface and creates a blanket of hot gas. If you start with an empty pot and crank your stove up as high as it will go. Then drop drops of water onto it, you might see the Leidenfrost effect. If you start with a pot of water, you have to have enough heat come into the pot to exceed what is called the “critical heat flux”. It is also called the “burn out heat flux” because when you hit it you often times destroy your equipment. You will never get there with a camping stove.
Jan 23, 2018 at 4:53 pm #3513895Clarification – “Greg got it right …”
Apparently wrong in my Leidenfrost WAG, and apparently close on my “moot point” post.
I just keep throwing sh*t out there. Sooner or later I’m gonna be right ;-)
Jan 23, 2018 at 7:26 pm #3513944Thermal conductivty represents the quantity of energy transfered by surface unit and time unit , under a temperature gradient. As such. it follows the same logic as electrical conduction to electrical resistance where conversions are typically simply inverted between the two.
If we think of thermal conductivity as an invert of thermal resistance (or insulating value) we can compare a metals “thermal resistance values” by simply inverting the conductivity numbers. It is much easier to see that 1/237 is much less than 1/21. Or, let me convert this to four place decimals: .0042 for Al and .0476. It is easy to see that the Ti is a much better insulator (>10times better) than Al. I would not choose a pot that insulates 10 times better than the alternative. Kind of like choosing an aerogel pot over a titanium one. This tells me that a Ti pot is only equivalent in thermal conductivity if it is ten times thinner. But, it is <3 times stronger.
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