New thermogalvanic tech paves way for more efficient fridges

There's not enough heat in the fridge to heat up any significant amount of water.

I would however like to see that waste heat being used for something like dishwashers or just being vented out (instead of into the room that might have to be actively cooled).

Waste water heat recovery, which heat exchanges with inlet water, would probably be more effective than heat exchanging with a fridge. Realistically both options are too costly for the limited benefit.

If you look at the temperature deltas, we really don't do much to cool our food. You can verify this by comparing the power requirements of a fridge with just about anything that heats water or food.

You could save some power, but not very much.

Thanks for that, it's great that its 10x better than the previous best effort. It's notable that it needs to get 20x better again before it starts to have useful applications :-).

Magnetocaloric cooling is used in cryogenics as are thermoacoustic chillers. I think there are some aerospace applications.

Ultrasonic vibration "fans": https://www.pcworld.com/article/2203172/frore-system-airjet-...

Imagine heat pumps 400+% efficient with 60% heat to electric conversion.

https://en.m.wikipedia.org/wiki/Johnson_thermoelectric_energ...

AFAIK, that's how lots of restaurants keep their stock chilled, at least in my area. They have relatively noisy exchangers outside connected to their fridges that are indoors.

That's actually commonly done in industrial cooling applications with rapid turnover (think dockside food storage warehouses), but it's not practical for the heat output of domestic units.

Even in parts of Europe and Iceland with ready access to a common municipal heat exchange, household refrigerators don't have have enough heat output to justify the infrastructure.

The typical domestic fridge just needs to "get cold once" and the remainder of its duty-cycle (aside from the rare holiday feast or party) it's just trickle-cooling.

Depends on where you are. Where I live, it's cold seven months out of the year so keeping the resultant heat inside the house lowers the heating bill somewhat.

I've always wished for a fridge that was mounted to an exterior wall. In the summer, it operates like a normal fridge but with the condenser coil outside of the house. In the winter, the compressor system turns off when the outside temp goes below a certain value and little door/shutters with fans regulate the temperature of the refrigerator either by letting in cold air from outside (if the interior needs to be colder) or from the inside (if the interior needs to be warmer to prevent food from freezing).

There's probably a few good reasons why this is not actually practical but I'm tempted to try something like it in retirement.

The very first household refrigerators had the condensing unit mounted outside.

You can see an example in this 1920s Frigidaire training video (which is also worth watching for other reasons): https://www.youtube.com/watch?v=W-t7DqOAMME

Even if true, no one is going back to an R-12 refrigerant because CFCs contributed to a hole in the ozone layer that the entire world agreed was a bad thing. [1]

The "last a long time" bit might be survivorship bias. They might last a long time (or not) but having one old working fridge does not prove reliability.

As far as I know, there was no ban on using old fridges and I don't think people usually throw away major appliances that work.

[1] https://en.wikipedia.org/wiki/Montreal_Protocol

They did often use better refrigerant back in the day, but it is refrigerant we don't use now because it is either highly poisonous or hell on the ozone layer. The compressor itself wasn't often all that efficient mechanically, but the good refrigerant helps make up for it, but also there is only so much to gain out of compressor efficiency. The biggest problem with old fridges is they were insulated like absolute garbage. Not only is the insulation often super thin, but the steel shell on the inside was rarely separated from the steel shell on the outside leading to a lot of heat transfer. So even with it closed they ran constantly almost like you did have the door open all the time.

You also have to consider its cooling capacity, you only need a little bit of cooling 95% of the time, but when you put fresh groceries in it or water in the fridge, until those are cooled down they are heating up everything else in the fridge and so stuff will spoil faster/easier. Some older fridges might take a long time to cool everything down if you put in more than a single item at a time.

But really, most fridge breakdowns are not because of a compressor failure or anything major, 99% of the time it is some simple electronic component. A simple bad capacitor can prevent your fridge compressor from kicking in. Or a thermocouple could go bad and not tell it to turn on when it should. Both of those parts cost like $2 to produce, but of course they choose more proprietary designs and configurations to make a generic fix more difficult which lets them markup the parts on prices. Which has the side effect of convincing more people to just buy new because they don't know if the 1500% marked up proprietary part was the only part near failure, and they don't have the knowledge or confidence to start tinkering on their refrigerator before they lose all their potential savings on spoiled food, or use an appliance repairman who will add on $200+ onto the inflated parts prices because they don't want the liability taken upon themselves if they were not using direct replacement parts.

Yeah am I reading that? 1.7 degrees Celsius is what they've achieved? That paves the way for more efficient refrigerators?

I thought paving the way meant a clear path to the end goal, because you already know the route and all the necessary engineering to get there.

> Did peltiers ever get efficient?

Not compared to gas compression. For a relaxed take on it:

https://youtu.be/CnMRePtHMZY?si=jusDm81RWkDF_HJ0&t=900 (Thermoelectric cooling: it's not great)

Though part of the complaints about the mini fridge is due to lack of insulation. But he compares it to his usual fridge, which has a similar power draw as this 60W mini fridge, and there's a 50x difference in volume to cool.