Rachel’s Team Pick: These Things for Your Tea or Coffee

Rachel does a lot of writing, so I thought I would help her out today by showing you a thing she found that she seems to be pretty excited about.

She’s talking about Coffee Joulies! What’s a Coffee Joulies, you ask? It is this:

“Phase Change Material” that is designed to melt and absorb excess energy until it reaches 140°F. At that point, the material begins to release the stored energy, thus maintaining the temperature of the coffee.

You just put them in your hot beverage and your hot beverage will cool down to an acceptable sipping temperature without becoming too cold, and it’ll stay that way for hours. Whoa that’s neat. You can pre-order a set from the Coffee Joulies Kickstarter page! Thanks, Rachel! I love you.

this is a thing you can pre-order

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Laneia is the Director of Operations and founding member of Autostraddle, and you're the reason she's here.

Laneia has written 927 articles for us.


    • I’m a liberal arts major, so take the following with a coffee bean of doubt, but here goes:

      Despite their touting it as a marvel of science, it’s just harnessing the everyday business of phase change. My totally haphazard guess (but probably correct) is that there is a mass of paraffin (or another type, perhaps even a blend) wax inside these stainless steel babies. At room temp of 22-23 degrees Celsius, paraffin is solid.

      Paraffin wax however, would melt in the neighborhood of 47-64C or 117-147F according to wiki. A bit of googling suggests that drinkable temp for a beverage is in the neighborhood of 55-60C or 131-140F. The specific heats of paraffin and water aren’t so far off, but the lack of stainless steel estimates online is annoying (also I can’t seem to figure out how much these things weigh so I can’t do the Q=mcdeltaT)… but I digress…

      That being said, when a substance is in a solid state the atoms inside it are moving very little, vibrating a bit, but they get more active the hotter they get. Thermal energy gets converted to kinetic energy at the molecular level. (If there are science people up in here, stop me now because I’m probably wrong but..) Anyways, the point is that if you drop one of these room temp 23C Joulies into your tea/coffee situation at 100C, it undergoes quite rapidly a 37degree temperature delta. Because stainless steel and paraffin wax are excellent conductors of electrical and thermal energy, their uptake of this extra environmental energy would be quite rapid, hence the 2x faster cooling period. The wax inside would therefore melt and become liquid.

      The phase change is reversed then, as the outside temperature of your tea/coffee situation decreases as its remaining heat diffuses into the environment, i.e. your chilly body and/or if you are drinking this beverage in a meat freezer, as you do. Anyway, the point is that the extra energy these little Joulies have taken in to melt the theorized wax inside is slowly being released back into your beverage, i.e. the wax is becoming solid again.

      TL;DR: this picture sums it up

  1. I would be ALL OVER THIS… if they didn’t retail for $50. That is more than a week’s groceries. That is two guitar pedals. That’s the super deluxe new An Horse Walls bundle with the a CD, signed poster, LP, and pillowcase AND $10 left over to buy about 7 cups of coffee from a locally owned coffee shop.

    But if I had money, these things would be so frigging awesome.

    • i kind of felt that way but then i had to stop for gas on the way home and thought “they are the same price as a tank of gas basically!” and i fucking hate buying gas so i thought it would actually feel good to buy them, like HA here is $40 i am spending on something awesome that is not a fossil fuel.

      also if you buy them in the next 6 days through kickstarter they’re $40. also i’m asking for them for my birthday/christmas. so.

  2. OMG! Completely want these super bad. I reheat my tea/coffee a zillion times throughout the day cause I drink it so slow and they just moved the microwave in my office to somewhere far away/where I can’t find it. seriously amazing.

  3. I emailed all my coffee f(r)iends and one of them emailed me this:

    An interesting concept, but quite literally, the same thing happens with a rock or anything that has a mass to absorb heat. The concept of the “it freezes on the inside at 140 degrees” is cool and obviously their selling point, but a basic understanding of the law of conservation of energy says that it changing its state of matter (liquid back to solid) isn’t going to do anything special in terms of the transfer of energy. I just called my thermodynamics friend to confirm this… there’s nothing special about that transitional point in terms of its exothermic reaction; it’s not as if when something hits its freezing point it gives off a disproportionate amount of heat. In that sense, something that would be more effective would be something that would have a higher rate of thermal conductivity (i.e. – copper), but then you’re just putting pennies in your coffee, and that doesn’t sound very cool.

    This makes me very sad. Rebuttals? :(

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