No Compressor Fridge?

My family and I are currently building and off-grid cottage with a 900W PV powered battery bank and I am looking for efficient ways to reduce our electric consumption.  When it comes to the fridge, I know there are all sorts of possibilities (propane, efficient electric, geothermal, etc.) But i was thinking the other day as i walked out of the cold into a warm gas station just to hear the fridges humming trying to replicate exactly what was happening outside...cold.  Could one build a insulated box inside, against an external wall that had a low electrical load "valve" that opened and closed via a user set thermostat?  This would allow cool air into the insulated box and not suck up the watts from a compressor.  Of course this would only work in non-summer weather but then you have fresh food to eat and no use for refridgeration.  A root cellar is definately in the works for the future, but I think this would be a nice little convienent option that depending on the valve device would be relitivelay inexpisive.  Anybody have any ideas on what could be used for this vavle?

I saw this here a year or two ago. I thought that it was a great solution for those of us who live where there is a cold winter.  fourmileisland.com
kent

Here's a "fridge" which works by evaporation:  http://www.scienceinafrica.co.za/2004/september/refrigeration.htm

http://www.instructables.com/id/Make-an-Evaporative-Terra-Cotta-Beer-Chiller/

I've seen some systems use a small fan with a thermostat to bring in outside coolth.  I could not begin to tell you how to set it up, but I would guess that it would be like any other fan with thermostat.

As for bringing in the freezing cold to your ice box - find something to freeze and refreeze water in outdoors and bring that in and put in the ice box. I see old ice boxes on Craigs list all the time - they look cool, but look real easy to make also.

You can make a mini-cellar by burying a trash can with the lid only sticking above ground and then have some straw and rocks cover the lid. ( If you don't need to get into the mini-cellar very often you can even cover the lid with loose dry soil and wood.) When I was a kid my dad and I buried a wooden box full of apples in the garden. Near spring we dug it up and had apples to eat.

something to consider, I toured a strawbale home in spokane, very well designed, where the walk in pantry did not have heating to it and had something very simple, a window. this window could be opened to keep things cool. I understand this wouldnt keep milk from spoiling most of the year, but I loved the usefulness of the room being well designed.

Hello Ginger Roots,

The valve your after can be made using a spring and peice of leather ot other. Srings contract when cold and expand when hot. Think of a reverse theromostat action in your car. When the temperature is low the spring contracts opening the vent to allow cold in. When the outside temperature rises the spring expands closing the vent. Experimenting with hot and cold water will give you temperature setting of open and closed. The loner the spring the more sensitive to temperature opening and closing.

Cheers Peter

I like Peter's spring idea for it's simplicity.

I've lived with old, inefficient fridges for about a decade now. Every time the cycle up (mine just did) I get a little bummed out. I keep thinking about the joke about the salesman who sold freezers to Canadians.

I've designed solutions to this once or twice but never tried to actually do something. I'd like to convert my fridge to convection. Two pipes, one dumping cold air into the freezer section and one draining warmer air from the cooler section (this would work better if I put my fridge upside down). The challenges are to get a thermostat on my pipes set so that they kept the fridge a degree or two below where the compressor would come on. Too cold is no good. Too warm and the compressor would come on.

So. ABS pipes running through the walls, flat sections glued into cut out sections of the door gaskets, a thermo-regulation set up that came on and turned off...

They make a thing to open the windows of a green house when it gets too hot inside. I think they are hydrolic cylinders filled with an oil that expands and contracts. There is a screw setting that allows you to set the temp when it will open and close. I think that would work to open the vent when it got too hot inside the box and close it again once it had cooled down. A Bi-metal spring would also work if it was strong enough to move the vents. Both of these options work with out any electric or any outside power source, that is their advantage over fans and thermistates in my opinion. The idea would only work for the 4 or 5 cold months, but, you have free cooling for those 4 or 5 months. That sounds like a win.

Lots of old houses had a cool room. All that's needed is to keep it reasonably well insulated from the rest of the house, and a vent at the bottom and another at the top to allow hot air to escape upwards while drawing cold air in. It's completely passive. Don't just insulate a room -- you need the airflow to avoid moisture and mold issues. I would also consider another vent to the inside of the house for when it's well below freezing out to allow some heat in. You still need to make sure there is airflow, or you will end up with moisture and mold issues. You can either use the room directly, or stick a fridge in it.

I don't think you need to worry about the valve so much. There may be some occasional manual adjustment needed to the vents, but for the most part the system will be self-regulating. When the inside is significantly warmer there will be a greater convective current and vice versa. This works to your advantage, because when it's cold inside and out you don't want it colder, and if it's warm outside you don't want it sucking warm air in. If sizing/adjusting the vents is an issue you can also regulate the temperature by using thermal mass inside the room, and that's as simple as storing water at the bottom to heat or cool the air as it comes in.

If you do decide you need some additional cooling in the marginal months an exhaust fan should do the trick. If you're running solar, you'll probably have excess energy this time of the year, so efficiency isn't as big of a deal. I suggest picking up a window fan with thermostat (perhaps size your top vent to the fan).

If you want something fancier, what you're looking for is a differential thermostat/controller. http://www.youtube.com/watch?v=_MgdCMe3gTE

I saw on the internet some time ago about a guy that had what amounted to a big radiator mounted under the eves of his house. There was some kind of solution in it that would not freeze and it was setup to thermal siphon to a tank of water that this system would freeze into a solid block of ice by spring. His "refrigerator" was a metal box that was surrounded by this block of ice, and of course the whole thing was super insulated. It wouldn't store frozen food, so it couldn't function as a freezer but otherwise it worked good.

The part that was outside the house was basically a pipe with fins attached to it. When the weather got warm there were some valves that could be shut. It used zero electricity, but does require that you live in a part of the country that gets well below freezing part of the year. And if you didn't have enough ice to serve as the thermal flywheel, before it got to winter you ran out of ice.

Someone in this thread earlier referred to this:

http://fourmileisland.com/IceBox.htm

I found this a few years back and the more I look at this the more I want to try it. My only question (that I could not find an answer for) is: what is he using for a "refrigerant"?

In trying to avoid the commercial, non-renewable refrigerants, the only idea I've come up with is ammonia which is, I think, highly volatile and can continue to flow in sub-freezing temps. Any thoughts?

If it turns out that ammonia IS a solution, my next project is going to be how to create/collect ammonia.

Any ideas?

Roger.

Plain old air will work if you can engineer your system to use it.

Ammonia has been used as a refrigerant for over a century, but as you point out, does have toxic considerations.

You can also use propane.

Mark - Looking for a long-term, passive, petroleum-free solution so propane is out. Ammonia is a hazardous gas, but where I'm planning this installation any leak would go directly out-doors.

I wonder if the reason I'm nervous about just using air is the heat carrying capacity. Also, I guess, the "co-efficient of expansion" (if such exists <grin>) concerns me - something that contracts more in the cold will sink faster to encourage the rate of heat transfer.

Or maybe I'm just concerned that "air" isn't high-tech enough... The original plan calls for 1/2" copper - I wonder if 3/4 or 1" would be more effective. It wouldn't matter in the winter, but in the shoulder seasons (especially late summer/early fall) the ability to cool the water overnight might be important.

This is one of the few times that I wish I had done some more practical education than my degree in Music - I don't have either the science or the practical to figure it out.

TIA
Roger.

I know you don't like hydrocarbons, but butane may work very well. It boils at about 31°F and ought to work well in that fridge setup. It's twice as dense as air (when gaseous), so for safety, cut a hole in the floor. You probably want an emergency drain in there anyway (and make sure that drains straight outside. Don't tie it to the septic (odor) or weeping tile (radon) systems. 31°F is a lot warmer than -20°F, so the system should work far more effectively, and you should be able to get away with much less volume of pipe and gas.

On the other hand, ammonia requires an open flame to burn. It won't burn on its own. It's lighter than air and room temperature and will dissipate. And it stinks bad so you know there's a leak. And it's probably the refrigerant the guy used.

Mark:

Thanks for your reply and the information, especially the facts about venting.

I'm not sure I understand your point about "31°F is a lot warmer than -20°F" - are they the temps at which ammonia and butane change from vapour to liquid? The lower vapour/liquid temp. ("boiling point"?) makes sense to me to make circulation easier.

BTW, if I use propane/butane, what kind of pressures will there be in the system? Would it be different for ammonia? (This question is based on the notion that a system under less pressure would be more stable over longer periods - but I don't know if it's true or not...)

Roger.

I use a Sunfrost fridge with a 720 watt PV system. It works great until we get into our cloudy winters. I plan on putting a small radiator inside the fridge and one outside and using a water/antifreeze mix and a 5 watt EL-Sid circulating pump. I have been using a 10 watt EL-Sid for my hydronic heating and it works great. I'll use a 12v temperature controller set a couple degrees colder than the thermostat on the fridge so anytime it is colder outside than in the fridge, the pump will turn on. You would need the same type of differential temp controller if you use a fan/air setup but I think it would be harder to prevent reverse leakage when the fan wasn't running.

Roger Priddle wrote:
I'm not sure I understand your point about "31°F is a lot warmer than -20°F" - are they the temps at which ammonia and butane change from vapour to liquid? The lower vapour/liquid temp. ("boiling point"?) makes sense to me to make circulation easier.

BTW, if I use propane/butane, what kind of pressures will there be in the system? Would it be different for ammonia? (This question is based on the notion that a system under less pressure would be more stable over longer periods - but I don't know if it's true or not...)

Yes, 31°F and -20°F are the boiling (liquid/gas) points of butane and ammonia.

With ammonia you're likely dealing with a gas only all year unless you live in the midwest (or use a pressurized system). You'll get some convective action in the gas, but it'll be slow.

With butane, when it's 31°F or colder outside the butane will rapidly condense on the inside of your radiator. Like water on a cold window, the liquid butane will stream down the inside of your pipes. When it hits a warmer section of the pipe it'll boil off, extracting heat. Since the boiling point is below the freezing point of water, the water will freeze before the butane stays liquid. Ice is actually reasonably thermally conductive (it's about 15 to 20% more conductive than concrete), so the heat from water outside the ice will migrate through the ice to keep boiling the butane (it would work similarly with any refrigerant).

I don't know what kind of pressure you'd need to use with the ammonia system. For the butane system, if adding gaseous butane only (I assume you'll build this when it's above freezing), you'll actually end up with a negative pressure system when the butane condenses.

The butane system should also be easier to build -- I imagine a simple vertical pipe, sealed at both ends (filled at the top). You shouldn't need anything more complex, as the gas will easily flow up as the liquid flow down the outside. If you decide to do a fancier design, just make sure there are no gravity wells or traps for the liquid to get caught in as it trickles down. I'd go with a thick-walled metal pipe for its better conductivity and it'll hold up to the ice better.

An ammonia system will need a system that encourages the gas to flow. You would probably want a loop of some sort. The "hot" ammonia should go straight to the top, then through coils or folds to cool. You'll then want to pipe it straight to the bottom (while it's coldest) and run it through coils or whatever as it goes up.

It would depend a little on what your seasons are like, but here in Saskatchewan we get very cold long winters (usually, this one is being exceptionally mild). But I was told the other day how people did it in their younger days here. It was a general conversation so I didn't get all the details but this is what I understand.

They had a well insulated room, (probably insulated with dry sawdust) dirt floor. which they left open to freeze the ground. Then they packed a bunch of sawdust into it and wet it well, then got the kids to come in and stomp it down as tight as they could. Then they would repeat layers, each layer freezing solid. They buried boxes of frozen meat in the sawdust. up to the lid (not sure if they ever actually completely buried the boxes or not. I THINK they would hang blankets between the area where the meat boxes were buried and the area of the room that they kept stuff that shouldn't get frozen. Apparently the meat in the boxes would easilly stay solidly frozen until the following summer. I didn't ask how deep the layers of wet sawdust were but I imagine they were fairly deep, and the compression of the wet sawdust was the secret. Actually, there was a time when such a substance was used to make fake ships during the war and they apparently stayed together long enough even in the ocean to make the effort worthwhile.

They took the sawdust out and used it as mulch or whatever and used fresh clean sawdust every year. I assume that was to avoid mildews and other nasties. So now to find a source of sawdust....

I guess the thing is that it is very nice not to have to go out to an outdoor room to get your milk and so forth in the dead of winter so nobody does this now. With the cost of hydro steadilly climbing it may come back into vogue. I hadn't heard of this before.

There was a school in Mass (I think) that built a super insulated room and then filled the inside perimeter with milk or soda bottles filled with frozen water. Sort of like a modern day version of the ice house without having actually to go cut ice. The bigger the container the longer the contents would stay frozen. I haven't been able to track anything down as to how successful that was.

Pam and Mark - thanks both for replies.

I'm really looking for something that will be perfect - IOW, not possible. I want it to be passive and not involve any petroleum products.

Is there an alternative to ammonia with a lower boiling point even when not pressurized? I designed my house with a "mud room" (unheated but insulated) porch on the north side of the house, about 10' x 20'. It's sort of an airlock that opens to the kitchen, so putting an ice-box there would not be inconvenient.

It sounds to me like the packed sawdust was used to hold the water that froze. Not having a convenient source of sawdust in bulk (I live in Central Ontario), I can do what I did with the house - reclaim batt insulation from houses being demolished - to build a super-insulated box that holds a permanent volume of water that I can freeze in the fall.

It can be very space-inefficient - the only real challenge is the coolant medium and how to keep it moving. I can imagine that plain air would work (albeit slowly - I don't think the heat-carrying capacity is high) and something as simple as a bicycle pump could be used to start the air moving...

Again, my theoretical and practical knowledge are lacking here - once moving, what are the chances that heat energy transfer will keep it moving? Inertia vs friction? (yes, I do understand that "You can't push on a rope!") But I've got -14c outside tonight - there should be some easy way to lose heat from water into that environment...

And I don't need the whole mass to be frozen early in the winter, just in the 4c range for the fall would work fine. The value of the ice is in the potential to cool food into the spring and summer, so if it takes most of the winter to cool the block down to -10 or -20, that's ok.

I really appreciate the discussion - sometimes I have to go over stuff a lot to figure out where my fundamental error is - so thanks for your patience.

Roger.

Hello People,

Ammonia as a refrigerant is very old. Its greatest problem is it eats out just about every metal known to man. hence being left behind years ago. Todays Refeigerant is Carbon-CO2 otherwise known as R744. It boils at minus 40* Celsius. We switched from Ammonia to CO2 some six years ago with great results however the fridge workings are slightly different to that commercialy available and a whole heap cheaper. The other advantage is when the fridge action cools the CO2 is then direct to heating to form gas pressure driving a hydro turbine. Where otherwise it would absorb heat of from that needing cooling then pass on to cooling again as per normal fridge. The pump system that makes the whole thing work is attached. CO2 after exiting the pump continues to follow a path exactly as if in a compressor fridge but has no compresser. The pump is known as the DaS Valve. The same pump mechanism propells a hydro turbine by use of CO2 gas pressure upon water.

Part of what I like about the fourmileisland ice box is its simplicity. It uses standard finned copper heating pipes as the air to refrigerant heat exchanger. all the piping from the top of the heat exchanger slopes downward to the ice box. The refrigerant cools and condenses in the outdoor heat exchanger and flows as a liquid down to the ice box where as it freezes the water it evaporates and raises as a gas back to the outdoor heat exchanger. I have to believe that matching the boiling point of the refrigerant to your winter temps. and having the piping slope down to the ice box is critical.
kent

Hello Kent,

Absolutely spot on about piping.. Ammonia is an excellant gas for such given its solubility in water. The lesser the outside temperature the faster ice will form as the Ammonia liquid is more chilled in the cooler weather. Its almost a copy of "Einstiens absorption fridge. The difference being Eisteins use of flame heat got the Ammonia heat much lower than its natural liquidification temperature.

Cheers Peter

Just a funny story on ammonia refrigeration system. I used to have a business where I did industrial maintenance for manufacturing plants. I called an a meat processing plant that had a very large ammonia system. They had a mechanical room with pumps driven by 50 hp electric motors to run the system. The owner of the business took me into the pump room to show me around and informed me that it was an ammonia system. I told him I could tell by the smell, to which he responded that he had been there so many years he could not smell it anymore. Dang it was so strong it made my eyes water!!
kent

On another note: I have wondered if a no moving parts freezer could be made if a salt brine was used rather than water. I would be curious to know how cold and for how long it would take to make a walk in freezer in addition to a walk in ice box for storing harvests. The biggest thing I see is that we would be loading the ice box with things like apples and fruit at a time of the year when it would be at its warmest point after summer. My thought would be to also have a normal electrical refrigeration system to start the sytem in the fall until we had enougn below freezing weather to take over. Part of my thought would be to use straw bale construction with the outside walls built with the bales on end the long way to get a 3-4' insulated wall.
kent

Hello Kent,

Freezers with no moving parts are far easier to build than fridges with no moving parts. Carbon-CO2 heated above +33* Celsius turns into Dry-Ice -40* Celsius. (see Supercritical CO2) Its an odd behaving gas. Example sealed tube with a block of Dry-Ice at the bottom. Apply heat Dry-Ice turns to liquid at the bottom and Dry-Ice again at the top. One sticks the icy bit into the box and leaves the hot bit poking out. No need of any electricity. Straw bale insulation is a spot on idea.

Cheers Peter

The co2 idea is interesting, but a bit intimadating on a build it yourself scale. I may need some help here, it looks like the critical temp and pressure is 32C and 72,9 atm. I consider myself a pretty good builder and have experience with fairly high pressure gas and steam applications. However we are talking a system of piping that has 1071 psi of pressure. This makes construction very difficult and expensive. Am I missing something here?
kent

You might want to look around for the 4x4x8 straw bales if you had any way to unload and place them, they'd put up your wall in next to no time and have fewer joints to leak air through. Not too sure about condensation though..on one of the threads I think someone said straw bales had been tried for a cold house with plastic liners and it was a disaster. You might want to look into that.

Hello Kent,

Your on the button Co2 at +32 is 74 bar pressure but still Critical, after that point its turns Supercricritical. +100*C its 10,000 bar pressure. Childs play to line pipe and not expensive. Following fridge engineerings in place of a turbine a fridge restrictor is used through which the CO2 liquid passes into an expansion chamber where it becomes cold, picks up the heat out of the cabinet turns back into gas which is then cooled back to liquid. Exactly the same as a compressor driven fridge but without the compressor. The same effect occurs if only gas is used as shown by "Einstein". A freezer only needs the Das Valve. After sufficient Dry-Ice the hot gas/liquid is vented and held out untill a fresh face of Dry-Ice needs be formed.

Construction fridge, freezer or turbine generator are completely constructed by cut and weld of pipe with a ball thrown in as one way valve and gas escape valve. However cut and weld Mitchell turbine generater reduces effiiciency from 82% down to 60%. Off the shelf hydro turbine 82% efficient, one litre capacity, 60 RPM, 9 bar pressure (-10*C) is 720 watts and 10,000 bar (+100*C) is 720 Kilowatts increasing by volume, revolutions, or heat. Both rely upon the DaS Valve pictured earlier which is in its complete form no missing part.

Cheers Peter

Hello Pam Hatfield,

What you say makes a lot of sense. However when using straw bale for cold room/freezer chicken wire is sewn to the bales by passing through a long home made needle drawing on light wire which as well as holding the bales in possition allows them to be plastered with cement. This stops any condensation getting to the straw.

Cheers Peter

Hello Kent,

May be of help. The solid shown in red is Dry-Ice

Cheers Peter

Ok, I'm way out of my depth with some of the science here. Not that I'm complaining - I'm a highly motivated student!

I hadn't known about ammonia being so corrosive - that's a problem. If dry ice will work, I gather the only way it stays solid is under great pressure. Otherwise, one will constantly have to replace the dry ice? (not sure I understood that...)

Straw bales are great insulators but for now, how about using the insulation that gets landfilled every time a house is taken down? That's what I did here - R46 walls, R80 vertically with virtually no new insulation. If we can stop throwing valuable assets away all the time, maybe we can reduce the amount of energy we need to generate and the resources we need to use up.

Peter - I don't understand the reference to "74 bar pressure" nor do I know what a "DaS valve" is. Also (to no-one's surprise I imagine), I find "Freezers with no moving parts are far easier to build than fridges with no moving parts. " to be counter-intuitive. Surely, if I can built a freezer, it's just a matter of adjustable insulation to create a fridge attached to it....

Sorry to be dense - and maybe it will take a while, but I really am interested in understanding. So don your teacher robes and type on!

Roger.

Hello Roger,

Absolutely agree in recycle, any matreial from earth up makes excellant insulation. What we can do with what others frow away.

Dry-Ice forms under pressure that must be maintained if the Dry-Ice is to remain. This being so with all freezers the melting ice so to speak must be permantly manetained. Removable insulation or thinner insulation on one side of the freezer cabinet would allow cold to permeat into a fridge cabinet, however it will continue to do untill reaching the same temperature of the freezer over time unless the fridge was being constantly restocked so it never had time to reach freexing point.

One Bar pressure is 14.2 psi. The DaS Valve is posted back up the page, its that three pipe set up with the ball in one pipe. The DaS Valve is not needed to make a freezer/fridge only a sealed tube with the inner side where the Dry-Ice has formed coming into contact with the freezer cabinet. Back up the page is posted the CO2 graph pressure to heat, click on to open.

Nothing dense about your questions, I hope I have answered all, if not please give me a jog.

Cheers Peter

Peter - We have the advantage here of several months of below-freezing temps. (Today the high is -16c.) It seems to me that I should be able to use some minimal technology to freeze a large block of water that can provide a source of cold for months. (Up here, people used to cut blocks of ice out of the lake and store it for use all summer buried in sawdust.)

I liked the idea of a renewable refrigerant (like ammonia) that could be used to cool, then freeze the block of water. Since ammonia is so corrosive, something else would be better, but I'd rather avoid something that requires a highly pressurized system. If plain air would work, that would be great but the heat carrying capacity is fairly low nor, I suspect, will it move easily unassisted.

I wonder if the slope of the various components could be optimized to encourage flow. I suppose the diameter and materials composition would make a difference too, but my degree in music has not provided me with the necessary background... <grin>. (For example, I need copper to transfer heat (water/air, air/air) and 1/2 inch or 3/4 inch is lots for that, but I wonder if PVC lines (size?) joining the copper components would increase the airflow. I would think vertical differential would be significant but I really don't know...)

Anyway, I'm throwing out all the imaginary ideas that I've played with - I fully expect to be told that there are essential flaws in my understanding, but that's why I'm here, to be corrected.

Many thanks for any help you can give.

Roger.

Hello Roger,

Ether, Ethonal, Kerosene, Petrol will all do the same thing as Ammonia. All take in heat to phase change from liquid to gas. In fact any chemical that liquid at high temperature will work. However as to how much heat they need absorb before changing from liquid to gas you will need to look up on a chemical phase change graph. This is avialble on the internet. Sorry threw out my last copy with defunct hard drive.

Cheers Peter

Hello Rodger, Given the oustide temperatures are below freezing, why not just fill up plastic garbage bags with water and leave them outside for an hour or two. Low cost way of making large ice blocks. In the olden days over we use to dip wool bales in water them hang them out to freeze which made them water proof then fill them with water and let it freeze. These were then stored in outside cool room.
Cheers Peter

Peter - am I wrong in thinking that ether, ethanol, etc. are all very flammable? This might pose a bit of a problem for the insurance company... I know that phase change makes a very effective heat transfer rate but I want to be very cautious about the materials I use. Aside from efficiency, is phase change an important function in cooling/freezing water? (maybe I could just use rum...?)

The idea of moving blocks of ice could work but I'm looking for something that will store more cold and last longer. The plan from Four Mile Island freezes a single block more than a cubic metre. Carrying that in from outside might be a challenge, whereas using a passive circulation system allows for a bigger, more permanent solution.

As for wool bales, I think I must be imagining something different than what you used. Maybe I have an image of a cotton bale - several cubic metres and immensely heavy BEFORE it's soaked in water.

But please keep the ideas coming - it's got my brain working, at least!

Roger.

Hello Roger,

Yes all are flamable and Ammonia is deadly.

Nothing stores more cold than ice. The Ice Box you refer obtains its best cooling by the block of ice that forms after ten days. Its such a slow cooling system is useless for perishable items that need be cooled quickly.

The Ice Box system (Ammonia) you referer to takes at least ten days to freeze a block of ice, without any warm object having been inside the Ice Box

Estentialy all fridge/freezers work by putting a gas under pressure and forcing it through a tiny hole into a large chamber known as the expansion chamber in a fridge/freezer. The rapid expansion of the gas is what causes it to cool, this then picks up heat and goes to the cooling vanes that big mesh thing at the back of your fridge where the heat is given off. Lesser so on hot days as to cold days.

No phase change is not essential in refrigeration thogh where phase change occurrs cooling is quicker and deeper.

One can use low pressure CO2 driven by a thermal pump however such device does require the making of parts. Not sure as what costs that would entail.

Cheers Peter

Here is a page about the Icy Ball which seems to be a fairly simple project although it still does use ammonia. These used to be manufactured in both Canada and the US.
http://crosleyautoclub.com/IcyBall/crosley_icyball.html There are some links on it to plans for making one, but all the links everywhere emphasize how dangerous this can be.

Another site has instructions to make one but also has some serious warnings about the hazards involved.
http://lionheart.net/fridge/descript.htm

Any idea whether this would work using something other than ammonia?

Pam Hatfield wrote:Here is a page about the Icy Ball which seems to be a fairly simple project although it still does use ammonia. These used to be manufactured in both Canada and the US.
http://crosleyautoclub.com/IcyBall/crosley_icyball.html There are some links on it to plans for making one, but all the links everywhere emphasize how dangerous this can be.

Another site has instructions to make one but also has some serious warnings about the hazards involved.
http://lionheart.net/fridge/descript.htm

Any idea whether this would work using something other than ammonia?

Yes, it would work with butane, too. But I WOULD NOT DO IT. Butane is far more flammable than ammonia, and exposing a compressed container of butane to heat is asking to win the Darwin Award. Actually, same with ammonia. I wouldn't build one of these icy ball systems.

Mark - I accept your assessment of butane and ammonia as coolants but...

I have lots of cool - well, it's outdoors, but you get my point. I just want to use that cool to freeze water inside. There must be someway - if only because I want there to be! Sub-freezing is no problem. Since the "ice box" will sit in an insulated "mud room" that can itself be the fridge for the winter months, I just want to cool the water/ice as much as possible so I can use it when the outdoor temp rises.

I feel like I'm getting bogged down in a pre-conceived idea of what it should be. My goals are these: 1)it should be passive. I have lots of cold right outside the wall so that's what I want to use. 2) It should be safe, ie non-toxic and non-explosive.

Other than that, it doesn't need to be particularly efficient making the ice, just efficient at keeping the cold in. It doesn't need to be particularly "automatic" - I can open and shut louvres or move insulation. It doesn't need to be particularly compact - the mud room is 200 sq ft and, while I do have uses for some parts of it, a 4x6 footprint is not a problem.

Our ancestors used evaporation to cool food in the summer, ice to preserve it in the winter. My only concession to "modern technology" is that I want to make the ice in the mud room, not bring it in from outside, and I would like the process to be (relatively) automatic. My brain tells me "air" should be able to work as the "refrigerant" if I can make it move.

Ok, I've tried reduce it to a minimum. I know count on you and the other smart, practical people to tell me how to do it.

Roger