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Refrigerator that doesn't use power - could we build this?

 
pollinator
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Saw this link here: https://www.sciencealert.com/this-clever-new-refrigerator-keeps-food-cold-without-electricity

I've been thinking lately about peak oil and energy and what ifs and it has got me thinking about replacing some important things in my life that use power with similar things that don't use power.

I've tried the evaporative clay pot-within-a-pot thing, which cools food up to 10 degrees lower than ambient temps, but I'm trying to figure out if there is a way to legitimately have refrigeration - actual fridge temps - without any sort of power being used. The above link has an example that apparently uses a small bit of solar power but I wonder if it would be possible to do something without it?

Or - my brain wants to say I remember reading something years ago about some sort of cooling system using ammonia that caused a chemical reaction with SOMETHING that made things chill or freeze. Any thoughts?
 
pollinator
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Ammonia is used in many cooling systems, primarily in RVs. It is a less efficient system than a compressor based unit, but has the advantage of being powerable by thermal energy, so you can run it off propane.

I hear they are really miserable when they eventually corrode through and leave RV very malodorous...
 
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Physics says no. The reasoning being: If there was such a thing, you could create energy from it and that is not allowed.
That being said, a chest unit will not use much power. A 100W solar panel could run it, IF it wasn't for the startup current.
 
pollinator
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There's also this bit o' kit:

Coolgardie Safe - Wikipedia

Although it works on the same evaporative principle as the the Zeer pot.
 
gardener
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Hi Bethany;   I have to agree with the others. Other than the free fusion reactor in the sky there really isn't any free unlimited power... YET!
That said I've lived with various ammonia fridges (commonly called a propane fridge) for 40 plus years.  They all work , some are cheap plastic junk, some are horribly inefficient. The small ones that come in rv's are the worst. I have yet to have one rot thru, although I'm sure they do.

For the last 7-8 years we have had the best one yet.  Diamond brand, Amish built, 18 c.f.  sip's propane and freezes ice cream rock hard. (something the other older models couldn't do very well)

With a propane fridge you are still reliant on fossil fuel but it can be bulk delivered and does not need electricity.
fusion-reactor.jpg
[Thumbnail for fusion-reactor.jpg]
Free Fusion Reactor
 
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While it obviously doesn't travel, a root cellar is an off-the grid refrigerator.
 
pollinator
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Propane refrigerators don't NEED to run on propane.  There used to be kerosene versions, too.  I know you could retrofit one to run from a small rocket stove.
 
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This comes close to one of my mental enthusiasms.  (meaning I haven't built anything yet, but I have spent a fair amount of time reading and thinking it through).  It's high on my list of "Stuff that's So Cool I have to Just Have to Build it!!!"  (I think I just heard my patient, long-suffering wife roll her eyes.)

Ammonia is the most efficient refrigerant we have, which is why the big commercial freezing systems (fish packing plants, frozen food factories)  are generally ammonia.  Some ammonia based systems are probably more efficient than others, but that is the design of the system, not the ammonia.  

Downside is that anhydrous ammonia is dangerous if you get a big leak.  I would be cautious about using an ammonia system in my home, because ammonia has a strong affinity for water. In the event of a major leak, eyes and lungs might be the nearest water (blindness, lung damage, death are possibilities).  That's why home systems don't have ammonia anymore.  Coupled with that, the druggies use anhydrous to make meth.  Local law enforcement can get pretty interested if your inquiring about ammonia.  Still, just about every farm has a big tank of anhydrous ammonia on premises for fertilizing.  This is also where druggies get their anhydrous.  (I worked with a guy whose dad delivered propane to farms.  The propane tanks were generally next to the ammonia tanks.  He said occasionally they would find a glove on the ground that contained fingers.  It seems the druggies would get to screwing around with ammonia at night, trying to steal it and it would spray out onto their gloved hand.  They would jerk the frozen glove off, not realizing their frozen fingers would snap off inside like brittle sticks.  Like I said, it's a great refrigerant!

Ammonia also reacts with zinc, copper or brass, but doesn't react with iron or steel.  

There are a lot of old designs for ammonia systems around, some using water, some using MgCl2 or CaCl2for absorbents.  There may be some other absorbents I haven't read about.  The absorbents hold way more ammonia cold as apposed to when they're hot, so when you heat the absorbent it drives off the ammonia, which cools going through thin lines that radiate heat and then condenses and collects in a spot designed for that purpose.  When you take the heat off the absorbent and it cools, it will reabsorb ammonia gas, reducing pressure which lets the pooled ammonia evaporate.  Evaporation sucks the heat out of where the area liquid ammonia was collected.  The cooling is generally cyclical (refrigerates when the ammonia is absorbing, otherwise not refrigerating).  

I wouldn't want a system in my house, but I think the risk could be reduced to acceptable levels by having the system outside and using it to cool an insulated container of antifreeze which is then circulated to cool things indoors (fridge, freezer, A/C unit if you really go crazy).  Use a heat sensor to monitor the antifreeze temperature and turn the gas on or off.

Lots of possibilities!  I've read about a portable system developed by the military that could use a wood fire to heat (no specifics given).  I've also read about a system someone developed in Africa for keeping medicine cold that had a single daily cooling cycle, (the system used the daytime heat and night time cool to cool a small, super insulated medicine box.  If you were using water to move the heat around you could use a rocket stove as the heat source.  If you had a cold water source, you could cycle back and forth, heating and cooling the absorbent, greatly increasing the number of heat cycles in an time period.

 
master steward
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There's always the freezer wofati concept.  If you're not cold enough for a freezer it should still work as a fridge...
 
D Nikolls
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Sebastian Köln wrote:Physics says no. The reasoning being: If there was such a thing, you could create energy from it and that is not allowed.
That being said, a chest unit will not use much power. A 100W solar panel could run it, IF it wasn't for the startup current.




This is by no means a magical source of free energy.

It is using the lower temperature below ground, plus the cooling effect of evaporation. Both well known..

The question is, can the method described cool adequately in a given climate..
 
pollinator
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People used to gather big blocks of ice in the winter and store them together in an insulated structure of some sort. We have a lot better insulation now so we could make it last even longer, so if you live somewhere with cold enough winters you could sort out some kind of cellar system using stored ice maybe. Even here in ohio it's rare to have it cold enough for long enough to get more than the top several inches of standing water to freeze, though.
 
pollinator
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A couple of caveats: Here's an idea that does use power but shifts the load and lowers it somewhat. The company that the link is about has filed for bankruptcy just last month (12/2019), their website no longer exists. Who knows why the company failed, but the idea seemed sound.
Inhabitat article about Ice-Energy Ice Bear storage system

It is basically a powered version of an ice house, working on a small scale and daily schedule.
The A/C unit works in reverse to create a block of ice, so that when the A/C runs forwards (cooling the house) the ice is melted by the waste heat, reducing/eliminating the need for the compressor to run (the costly part of the A/C to operate).
The main benefit in a market like California, (where the company was) with high energy rates and peak pricing, is to be able to shift the load to "off-peak" times, using less expensive electricity.

Kind of like gathering ice in Winter and storing it in an ice house until summertime. It could be imagined that one could use the same technology to shift/extend solar PV collection for cooling use at night/24 hrs. a day.

 
No matter. Try again. Fail again. Fail better. This time, do it with this tiny ad:
Gracie's backyard - a film about permaculture farming in the far north with Richard Perkins (stream)
https://permies.com/wiki/133872/videos/Gracie-backyard-film-permaculture-farming
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