Y’all trying to come up with ways to cool it while I’m using my 5 temperature setting electric kettle to get the water hot enough to steep tea, but not boil.
I bought a kettle with a temperature selector. I have one degree of precision. Which is often overkill. It’s surprisingly useful to be able to heat water at non scalding temps. Especially for cleaning tasks, actually.
Increase the surface area and time for heat extraction to occur with extra loops in the water part (do they make metal silly straws?)
Get really fancy and use a counterflow chiller: create a two layer straw, where tea goes through one layer while cold water goes through the other layer in the opposite direction (obviously with an outlet somewhere besides your teacup)
While metal is a better conductor of heat, when looking at the effective rate of cooling you need to take the wall thickness into account. I think a plastic straw with it’s micrometer thin walls is unbeatable.
Edit: I have trouble finding information on wall thickness of drinking straws, it one source says they are 130-250 μm thick. That is thicker than I expected.
Leave a block of wood and a brick of steel in a freezer for 24 hours and see which one feels cooler - they’ll be the same actual temperature (at least negligibly close the longer they’re left) but the metal will feel immensely cooler to the touch due to its higher capacity for heat transference.
heat capacity: any short term experiment will measure heat capacity first, conduction second
locality of contact: contact along the whole length of the straw eliminates heat conduction along the length of the straw. A single point of contact (holding the straw with fingers instead of the whole hand) behaves differently.
I thought plastic straws were thinner than 0.2 mm, so maybe the metal is actually better.
It’s fun arguing about these technicalities though!
There are alloys of stainless steel (I forget the numbers off the top of my head, it’s been more than a few years since I worked in that field) that are perfectly fine and compatible for food/grade hot-process work.
I have these things called cold rocks for my scotch - they’re some kind of stone or earthenware dice-sized cubes that you leave in the freezer. Bought them at an alcohol warehouse shop we have here in Australia called Dan Murphys. They’re great for cooling without diluting.
I have some of those too. Problem is they’re nowhere near as efficient at cooling as ice cubes are and never cool my drink enough. It’s the melting (phase change) process that does the majority of the cooling with ice cubes, which you miss out on with these solid blocks.
I forget the exact maths, but a quick googling reckons it takes something like 84kJ to change the temperature of 1kg of liquid water by 20K, but changing the temperature of the same amount of ice from 0K ice to 20K water takes nearly 420kJ, or roughly 5 times more energy, which is why they’re so much better at cooling drinks…
304 and 316 are considered food safe. 316 is what most industrial food processing machines use. 304 is somewhat easier to machine, and cheaper, so lots of components are also made from that but it has less corrosion resistance.
Yep those are what I was thinking of; thanks for the cover, internet friend!
Also now I recall we were looking at pressure vessels made of Hastelloy; that was stupid expensive but they had corrosion-resistant properties that were very attractive for that application. And then management bought them and told us to deploy them for a process that was basically a low-temp filtration process. wtf, ok sure, the material is compatible but Hastellonis way overkill. Whatever, it’s your money to burn but damn.
I haven’t machined hastelloy but that’s some expensive shit. That seems like a poor use of that alloy though, but whatever lol as you said it’s their money.
I recently did a reactor that was supposed to be 1200C at 30,00PSI and wanted to use hastelloy X (alloy used in nuclear reactors) for that, but budget made us use 316 at a stupid wall thickness and lower the pressure to 5,000psi @ 800C. Same shit but opposite.
The melting point of plastic is 300+ degrees Fahrenheit. Even if you tried to drink tea that was still boiling in the cup you’d damage your mouth pretty good but the plastic straw wouldn’t melt.
This isn’t exactly true. Plastic is all different types of things and there is no one melting point, for example PLA (poly lactic acid) which is commonly used for things like disposable drink lids has a glass transition temperature of 60c (140f). Abs (acrylonitrile butadiene styrene) has a glass transition temperature of 105c (221f).
While the full melting point for these two polymers is higher than the glass transition, at those temps, your straw will start turning into a nice wet noodle.
The melting point isn’t helpful here because it defines the point at which the object turns into liquid, not the point where it deforms or gets damaged.
A drinking straw like that is likely made out of polypropylene with a melting point of 320F. Though the comment I replied to said “melt” specifically, if you wanted to reference the point before it begins to soften, PP has an operating temperature of almost 200F still. So that includes any hot liquid up to the point of near-boiling, which will be a bigger deal to your mouth than the straw. Thats why it’s used in drinking straws and the like.
Yeah, I won't drink anything hot out of plastic anymore: Corpos lied to us for decades that it was safe but it wasn't and now we're full of all sorts of terrible shit. The straw probably wouldn't deform, but it probably would leech all sorts of chemicals into the water.
Don’t think most plastic straws would melt, but they would probably soften and might infuse more chemicals into your beverage than it would if it were cold. At this point I’d just go for the obvious solution of repurposing an old heat exchanger from an AC unit or something. The strange taste will go away after a few times (probably).
Yeah, at slow enough drinking speeds there would likely be some noticeable difference in temperature after passing through the radiator, it probably just won’t be massive.
Now run your straw through a concentric larger straw and pump -30C glycol through the annulus. You can get your 96C tea down to 54C in seconds! Think of the efficiencies gained!!
Add comment