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The Problem with Microwaving Tea:
Typically, when a liquid is being warmed, the heating source — a stove, for example — heats the container from below. By a process called convection, as the liquid toward the bottom of the container warms up, it becomes less dense and moves to the top, allowing a cooler section of the liquid to contact the source. This ultimately results in a uniform temperature throughout the glass.
Inside a microwave, however, the electric field acting as the heating source exists everywhere. Because the entire glass itself is also warming up, the convection process does not occur, and the liquid at the top of the container ends up being much hotter than the liquid at the bottom.
A team of researchers from the University of Electronic Science & Technology of China studied this nonuniform heating behavior and presents a solution to this common problem in the journal AIP Advances, from AIP Publishing.
By designing a silver plating to go along the rim of a glass, the group was able to shield the effects of the microwave at the surface of the liquid. The silver acts as a guide for the waves, reducing the electric field at the top and effectively blocking the heating. This creates a convection process similar to traditional approaches, resulting in a more uniform temperature.
Placing silver in the microwave may seem like a dangerous idea, but similar metal structures with finely tuned geometry to avoid ignition have already been safely used for microwave steam pots and rice cookers.
Journal Reference:
Peiyang Zhao, Weiwei Gan, Chuanqi Feng, et al. Multiphysics analysis for unusual heat convection in microwave heating liquid [open], AIP Advances (DOI: 10.1063/5.0013295)
(Score: 5, Funny) by Rich on Wednesday August 05 2020, @10:25AM (8 children)
Microwaving tea is the worst civilizatory habit I have. Still, I find the taste degradation less bad than when the tea is kept on a tea-light, and it's MUCH more economical. Actually I'm more concerned with the slightly foamy top the tea has out of the micky. Not a big issue though, when you stir it - which also solves the heat distribution issues from the article.
I once found out that with adding milk to the tea before microwaving the foaminess goes away. That led to a funny episode where I did that at a customer site. Their resident senior PhD mathematician, usually a very thoughtful, precisely speaking guy, came in and switched into a panic mode that I had never experienced in the years before:
"What are you DOING there?"
"Me? I'm microwaving my tea." (thinking he is offended by such a cultural misdoing) "Works well enough for me."
"YES! But with MILK!"
"Oh, I figured out that if I add the milk beforehand, the tea will come out smoother."
"Don't you know there are PROTEINS in the milk?"
"Uh?"
"They might be bent by the microwaves!"
"Uh? You think like the prions of mad-cow-disease?"
"Yes! Precisely!"
"Um. I consider this safe enough. I mean, there are 300 millions USAians who have been using their microwaves daily on anything since when we've still cooked on fires. They would've gone into full retard mode if there was any effect."
"Yes! Precisely! That should be proof enough!"
I must say I was scared enough not to put milk into the microwave from then on ;)
(Score: 2) by RamiK on Wednesday August 05 2020, @10:56AM
Lol if you want to freak him out let him know about carcinogenic carbon electrophiles forming during heating... That should be fun :D
compiling...
(Score: 2) by mhajicek on Wednesday August 05 2020, @01:57PM (4 children)
There are proteins in meat and cheese, which are probably among the most microwaved substances. I think you're safe.
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
(Score: 0) by Anonymous Coward on Wednesday August 05 2020, @03:16PM
Nachos FTW!!
(Score: 2) by wisnoskij on Thursday August 06 2020, @12:52PM (2 children)
What sort of barbarian would put meat in a microwave?
(Score: 2) by Reziac on Friday August 07 2020, @02:23PM (1 child)
One who has figured out how to do so with precision. But it's helpful to have a low-powered microwave, so it doesn't instantly shoe-leather the meat. (Can't do it in the 'new' microwave, but in the old 900w I could cook delicate stuff. Even used it to make souffles.)
And there is no Alkibiades to come back and save us from ourselves.
(Score: 0) by Anonymous Coward on Friday August 07 2020, @06:06PM
You can do it in a new microwave, just use a low power setting.
(Score: 2) by hendrikboom on Sunday August 23 2020, @02:21AM (1 child)
I usually microwave my tea -- yes, the liquid tea itself, not the water used to make it.
I add milk *after* microwaving -- even if the tea ended up boiling, this helps limit the temperature to something tolerable.
(Score: 2) by hendrikboom on Sunday August 23 2020, @02:34AM
Oh yes. I make tea in a 2-litre teapot. Lasts me a full day if I microwave a cup at a time.