Why do we not have a household appliance to cool food quickly?

Question

We’ve had a microwave as an economical home appliance for a long time. Why do we not have a common appliance for cooling food in seconds?

In: Engineering

Answer 1

When you heat things up, you can apply a very strong heat difference. For instance, when you boil an egg, you put it in water that is about 75-100 deg. centigrade hotter than the egg’s original temperature. That’s gonna heat the egg pretty quickly. Or when you bake something in an oven, it’s not hard to get a temperature differential of more than 200 centigrade. Again, that’s gonna raise the temperature of your dish rather fast.

If you could put something in a -200 degree freezer, it would cool down pretty quickly too. Trouble is, it’s hard to make a freezer that cold. Your fridge runs at about 4 centigrade, and home freezers go to maybe -20. Expensive medical-grade freezers (e.g. the ones used for some of the corona-vaccines) might go down to below -70, and it’s possible to go even colder but it gets harder and more expensive. Basically, lots of simple chemical reactions (e.g. burning) and physical processes (e.g. running electricity through a wire) generate heat, whereas drawing heat away is a much less “natural” process.

You definitely can speed the cooling process up though, even with the small temperature gradients that are available in home settings. Let’s say you’re wanting to cool down a can of soda. One thing that will really help is to immerse the can in ice water, since water is a much better heat conductor than air. If you can keep the water moving around, that helps too, as this will replace water that’s been warmed by the can with colder water. So in theory, you could make an ice-water-circulator appliance for quickly cooling down drinks. The demand for such a product would be very small, though, as you can achieve a very similar effect with some ice cubes and a bucket when the need arises, and most of the time you can just avoid this issue completely by storing your drinks in the fridge ahead of time. It’s also not clear how to make this a particularly convenient product, unless it’s hooked up to a water source as well as a water drainage system (otherwise it’s not really better than a bucket, only with some kind of fan or pump to keep the water moving automatically).