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



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

You can put it in the fridge or freezer depending how hot it is and how quickly you need it cooled?

They exist in commercial kitchens and are called blast chillers. They’re incredibly expensive to run and quite large and heavy – the physics of making things cold is far more energy intensive than heating them up. Additionally, household demand for cooling just doesn’t exist to any great extent – most people don’t cook batch products like commercial kitchens, so they can be cooled in a normal way (spread out over a larger surface area and then transferred to the fridge) without being in the danger temp zone for too long, and anyway, most people aren’t as concerned about food hygiene at home as a professional kitchen would be. At best, the demand might be to get your beers cool fast, but a soggy paper towel round them in the freezer generally does the job.

Ultimately, all these elements mean that it wouldn’t be commercially viable to bring them to market as domestic appliances.

Heating something up is really easy. Heat is already generated as a waste product by many appliances, so making one that does it more efficiently isn’t that difficult. And with microwaves, it’s as simple as beaming energy into the food.

However, cooling something down requires a far more complicated process. Even the fastest flash freezers still take a lot of time. You could use something like liquid nitrogen, but that’s expensive and impractical.

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).

It would be cool if there was a way to chill something in the opposite manner of a microwave, ie., a microwave causes food etc to vibrate molecularly using high frequency energy. In a sci-fi world, would slowing vibration “remove” heat?

You mean the “Reverse Microwave” Brandon DiCamillo invented 18 years ago? XD