A man in a t-shirt and sport coat sits behind a table upon which are a small, black air fryer and a larger pale green model that looks more futuristic. Behind him is a black set of cube shelves (possibly IKEA Kallax) with different colored interiors lit and holding various bits of vintage technology equipment like landline phones and HiFi setups.

How Do Air Fryers Work?

Air fryers are the new hotness in the kitchen, but are they actually any different than a convection oven? [Technology Connections] walks us through the design of these countertop appliances to find out.

If you like your fries and chicken crispy instead of soggy, you traditionally had to eat out or spend the better part of an hour waiting on your food to cook to a crisp in the oven. Convection ovens significantly speed up this process by moving the air about and keeping the food from sucking most of the heat out of the stagnant layer just next to it.

It turns out that most air fryers are just a coil stove element and a fan placed above a basket which is just a fancy re-arrangement of the parts of a toaster or convection oven. The magic sauce here is the small size and the fact you don’t have to futz with pulling a hot wire basket out of your toaster or larger convection oven. The small size does give you a pretty big advantage in preheating and precise application of heat to the food for smaller batch sizes, but if you already have a convection oven, the advantages might not outweigh the additional space and cost of yet another kitchen gadget. We appreciate the sacrifice of eating “a lot of french fries” to test the differences between brands and conventional convection ovens for our edification.

If you’re looking for a way to make cookies faster instead of fries, how about this hack using a microwave and a heat gun? Or maybe it’s better to redesign the food instead of the appliance like this ramen in an edible package or these origami noodles.

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Hack Makes Microwave Cookies Fast And Not Terrible

Making a chocolate chip cookie is easy. Making a good chocolate chip cookie is a little harder. Making a good chocolate chip cookie quickly is a pretty tall order, but if you cobble together a microwave and a conventional oven, you just might get delicious and fast to get together.

The goal of this Frankenstein-esque project is to build a vending machine that can whip up a fresh-baked chocolate chip cookie on demand and make [Chaz] wealthy beyond his wildest dreams. We’re guessing at that last part; for all we know his goal is world peace through instant cookies. We’re fine with the idea either way, and his previous work on the project resulted in a semi-automatic cookie gun to splooge the dough out in suitable dollops.

The current work is turning those into something edible, for which a microwave seems a logical choice. Experience tells us otherwise, so off to the thrift store went [Chaz], returning with a used air fryer. He ripped the guts out of a small microwave, slapped the magnetron onto the side of the air fryer, and discovered that this was officially A Bad Idea™ via a microwave leakage tester. Round 2 went the other way — adding a conventional heating element to a large microwave. That worked much better, especially after close-up video revealed the dynamics of microwave cookery and the best way to combine the two cooking modalities. The result is a contraption that makes a pretty tasty-looking two-minute cookie. World peace, here we come!

Of course there’s plenty to say about the safety of all this, much of which [Chaz] himself cops to in the video. It’s important to remember that he’s just prototyping here; we’re sure the final machine will be a little more sophisticated than a heat gun duct-taped to the side of a microwave. Those cookies aren’t going to bake themselves, though, so you’ve got to start somewhere.

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Fixing A Hot Shop, With Science

We know that pretty much everybody in the Northern hemisphere has had a hellish summer, and there’s little room for sympathy when someone busts out with, “Oh yeah? You think THAT’s hot? Well, lemme tell you…” But you’ve got to pity someone who lives in north Texas and has a steel Quonset hut for a shop. That’s got to be just stupidly hot.

But stupid hot can be solved — or at least mitigated — with a little smarts, which is what [Wesley Treat] brought to bear with this cleverly designed shop door heat shield. When it pushes past 42°C — sorry, that sounds nowhere near as apocalyptic as 108°F — the south-facing roll-up door of his shop becomes a giant frying pan, radiating heat into his shop that the air conditioner has trouble handling. His idea was to block that radiant heat with a folding barrier, but to make sure it would be worth the effort, he mocked up a few potential designs and took measurements of the performance of each. His experiments showed him that a layer of extruded polystyrene (XPS) foam insulation covered with reflective Mylar did better than just the foam or Mylar alone.

The finished heat shield is an enormous tri-fold plywood beast that snugs up against the door when things get toasty in the shop. There’s a huge difference in temperature between the metal door and the inside surface of the shield, which will hopefully keep the shop more comfortable. We imagine that the air between the door and the shield will still heat up, and convection could still distribute all that hot air into the shop. But at least he’s giving the AC a fighting chance.

In addition to great shop tips like this and his custom storage bins, [Wesley] is a talented signmaker. He’s pretty funny too — or maybe that’s just the heat talking.

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A 1971 Thermos compliments this mid-century corner of my office.

The Incredible Tech Of The Vacuum-Seal Flask

I recently started using a 50-year-old vacuum-seal flask that belonged to my Grandpa so that I don’t have to leave the dungeon as often to procure more caffeine. Besides looking totally awesome on my side desk, this thing still works like new, at least as far as I can tell — it’s older than I am.

Sir James Dewar's original vacuum-seal flask.
Sir James Dewar’s original vacuum-seal flask. Image via the Royal Institute

Of course this got me to wondering how exactly vacuum-seal flasks, better known in household circles as Thermoses work, and how they were invented. The vacuum-seal flask is surprisingly old technology. It was first invented by Scottish chemist Sir James Dewar and presented to the Royal Institute in 1892. Six years later, he would be the first person to liquefy hydrogen and is considered a founding father of cryogenics. Continue reading “The Incredible Tech Of The Vacuum-Seal Flask”