Refrigeration / Ice making

[Guy_Incognito]

I've had a bit of a scan back through the board looking for topics on refrigeration.... and I've not really found that many about actual ice generation after TEOTWAWKI.

So, I'll post a few things here - suggestions are appreciated. Note that I live in a part of the world that drops close to freezing for just 2 weeks of the year , so comments like, "just leave it outside over winter!" aren't going to cut it .

I'm looking for alternatives that can provide enough ice to either keep things frozen, or can provide enough cooling directly to preserve food/medicine indefinitely. It can work in cycles, as long as the refrigeration produced can last the time between cycles.

I'll post a few things I've found below:
- Ammonia/water cycle "icyballs" are interesting. Heat em up for a few hours, refrigeration for the remaining 20-something hours a day.
- A salt / ammonia cycle (PDF) does pretty much the same thing as an icyball, can be solar-powered. A bit large for the solar powered version as above, but it makes about 10 pounds of ice a day. Fire-heated ones can do the same thing and are generally constructed like an icyball.
- Electric, that is, your standard deep freeze run from an inverter/gen set.
- Manual compressor driven refrigeration. As I repair car A/C systems for a living, this is the area I can experiment with the easiest, so I'll waffle on here for a bit

Car A/C's are huge. A car airconditioner, transplanted to your house, could easily keep half your house cool. They're rated in a pleasingly archaic term called "tons". That's "tons of ice melted in a 24 hour period to get the same cooling effect". An average Car A/C will be rated at 2 - 2.5 tons. Can you see where I'm heading here? You don't need 2 tons of ice every day for your average icebox. Which means that you should be able to power that honking great big a/c compressor via human means to generate a smaller quantity of ice as needed. My gut feel is half an hour of pedalling = hunk of ice sufficient to last the day out.

So, that's what I'm going to construct. A pedal-powered icemaker. I've crunched the numbers and generally everything seems plausible enough to try it out .

Goals :

- To be human-powered only throughout. No electric cooling fans/pumps/etc.
- Constructed out of scrap automotive parts.... probably with new pipework for convenience though.
- Run on a 80/20 propane/butane gas mix (about the same refrigerant capacity as R12 was). It's conveniently the same mix that portable camping stoves use .
- Able to freeze 2kg (5 pounds) of water in less than half an hour of moderate (er, not heart attack inducing) pedalling.

Are people interested in blow-by-blow updates of this thing? If not, I'll just dump it all on a webpage and link to it in the distant future when it's all done. And I'm open to other alternatives, so as mentioned up top, if you've got any info/links , post them.

 

[nancy1251]

I got a little freezer from walmart. It's a small chest type and it only takes three amps but it holds a lot. It is probably about waist high by about two by three feet. I can run it and freeze it from being thawed out using a 600 watt inverter and I have used a battery as small as a lawn tractor. It works real well when our electric goes out and it's a cheap way to go.
Hope that helps

 

[Dobbin]

Mother Earth News...

...in it's heyday (Sept-Oct 1975) did a few short articles about the "wood burning refrigerator." The theory the author expounded on ammonia absorption was solid but turning theory into practice was more than a bit weak or more accurately non-existant.

See http://www.motherearthnews.com/libr...rning_Refrigerator__Is_Now_Under_Development_

Old MEN was/is still a wealth of information on a lot of alternate energy topics but sometimes their sales pitch went beyond their product.

Frankly, I have my doubts about a "pedal powered" refrigerator. A human being on a bicycle can continuously produce only about 100 watts maximum (or perhaps a bit more if you're an Olympic caliber bicyclist.) 100 watts is only about 1/8th of a horsepower.

If memory serves, automotive air conditioners while in service steal from the engine about 5 to 10 horsepower - those old 40 hp diesel rabbits with air conditioning were seriously challenged acceleration wise. And with pedalpower/mechanical refrigeration you still have the COP (coefficient of performance) factors of refrigeration cycles generally to get past.

You might do better to get a small "dorm size" refrigerator. The Sanyo where I work is rated at 112 watts and I expect it is actually "on" only about a third to a half of the time. This is a pedal power electrical load you could keep up with if you use a battery/inverter. Also, if you insulate the exterior of the dorm size refrigerator better, you could increase your chances of continuing success.

Pedalpower might also work for "Thermionic" refrigeration (seebeck effect etc.) Those Coleman coolers that use this method for a sort of weak kneed beer cooler are real and do work. Kinda. Too bad they can't freeze ice.

I have the ultimate respect for Homepower magazine. But the early Homepower magazines had a lot more "homebrew" than today's magazine to include a lot of refrigeration comparisons - mostly considering Sunfrost refrigerators coupled to PV panels. It's almost too bad that Homepower is now "grown up" and becoming more mainstream. Get yourself the Homepower archive CDs, namely Solar 2, Solar 3, Solar 4, etc. for more detail on this.

But regarding the change in Homepower Magazine, there's a lot more options/sources for alternate energy equipment than there was in the 1970s. And conversely, less people who want to "experiment."

Market driven I guess.

Best of luck and keep us posted,
Joe

 

[Charlie]

Rent the movie "Mosquito Coast" or move to Siberia (where I live) and forgetabout the refridgeration issue. We have enuf snow and ice here delivered free of charge to last a lifetime, much less a few summer months.

 

[Guy_Incognito]

I prefer a warmer, rather than cooler climate Charlie, so I'll pass on the moving to Siberia plan.

And I've got an inverter that can run my deep-freeze - this is just an excercise to see if it can be done. And then I can either brag about building a pedal-powered icemaker, or I can authoritatively say, "It Can't Be Done." - either way it's win-win.

Ok , I'll post the math here. I'm using metric units, because It's Just Simpler :

To freeze 1kg of water, you need to remove 334kJ of heat, plus a bit more to bring it from room temperature to zero degrees first (4kJ/kg per degree C above zero).

Now, 1 watt is equivalent to a Joule per second.

So that's 334000 joules to be moved from the water to (somewhere else), in my time limit of 1800 seconds (half an hour) to freeze 1kg. That's about 185 watts continuous in that time frame. Double that for my desired amount of 2kg.

Now, from a random medical report on the web :

A fit 25-year-old man can generate 650 watts while bicycling for a few seconds and can maintain a power of 400 watts while bicycling for 1 minute, 230 watts while bicycling for 10 minutes, and 175 watts while bicycling for 30 minutes. He is able to reach 275 watts in a progressive incremental (increasing at 16.7 watts per minute) test to capacity; this power represents peak exercise and is the power at which maximal oxygen consumption (3.3 liters per minute) is measured. To put these figures in perspective, brisk walking represents an output of approximately 50 watts of power and an oxygen intake of 0.8 liters per minute.

So, one could almost do it by pedal power alone. But wait! We're forgetting the COP of the refrigeration system. Again, general research has it that a hydrocarbon refrigerant system(1) is good for a COP of 4 to 5. I'll reduce that for frictional and pumping losses in running an (likely worn) automotive compressor at low speed. I intend to use a large barrel of water as a heatsink for the condensor, which will also improve the COP as opposed to an air-cooled setup. You'll also end up with warm water at the end of it. (eg, 10L at 25 degrees C, will end up at 35 degrees C. A bit more ice making and you can have a warm shower afterwards ) I'll make it worst case a COP of 3.

So, with a COP of 3 and the need to shuffle 360 watts from here to there for half an hour gives you 120 watts of input energy. That's a fair bit of pedalling, to be sure. But it's not heart-attack inducing (for me, anyway), and you can always pedal slower and extend the cooling time. And of course, if you have any other supply of rotational energy (engines, waterwheels, er, small children) you can adapt it to suit.

(1) Comparative performance of Hydrocarbon Refrigerants (PDF)

 

[Rob]

Joe,
I've thought about the ice problem somewhat myself. I like Peltier Junctions(used on the Coleman fridge) The problem, as you might know, is that those junctions only allow a temp differential of about 40 F.
So in order to get down to a freeze we have to bring the surrounding temp down to around 60F to give us a good solid 25F for our freezer.
Since the mean ground temp is around 55F we would have to either bury our fridge (essentially a root cellar) or run a length of pipe under the ground. (About 50 to 100 feet for our fridge)
The other thing is to make the fridge small, say a one foot cube highly insulated.
I like the idea of peddle power but What I would do is combine it with batteries. That is, charge the batteries over a longer period (peddle power or solar) then use the batteries with peddle power to get your ice.

I did build a peddle power bike to see what I could generate. I made the alternator out of NdFeB magnets, three phase brushless and I can generate about 80 to 100 watt hours into a resistance load on an old exersize bike with a chain drive to the alternator. I can easily generate 40 or 50 watt hours without to much sweat but I'm a bicyclist, although I'm also over 60 now, so I don't have the juice of you younger guys!

Just some ideas.

 

[gillmanNSF]

Funny, I've been researching ways to have a refrigeration, including DC powered and propane powered. For DC, I've been thnking about Coleman's Thermoelectric Cooler or Engel's Portable Fridge/Freezer/Warmer, both powered with a cigarette lighter adapter. The Engle unit is more flexible but pricier than the Coleman which just keeps things cool.

http://www.coleman.com/coleman/search/SearchResults.asp

http://www.compactappliance.com/xq/...opping/product/MHFD015ED.htm?mtcCampaign=1494

For a power source I was thnking about the foot-powered Weza Freeplay. Create your own store of power and use it to cool or freeze things and to power other DC gadgets.

http://www.ccrane.com/more-categori...y-freecharge-weza-portable-energy-source.aspx

I don't think I'd personally need a freezer, and, since everything I will be cooking in an emergency situation, will be consumable within a day, I don't think I will need a fridge either, but it might be nice to have. So I'm currently debating. These DC coolers are also useful on long road trips, which I do twice a year, so I'm leaning on getting the Engel.

I found a cooler than uses AC/DC and propane @ 0.55 liters of propane per 24 hours of cooling, which comes to 32 days for a 20 lb. propane cylinder. That's good for short-term emergencies, but for any Katrina-type or large EQ scenarios, I would want something that can be sustained longer-term.

http://www.lpappliances.com/RC3000.html

 

[WFK]

Muscle power:

I remember an old rule: 1/8 HP is what men can do for a longer period.
That makes it about 100 Watts at 100% efficiency.
But I think "guy I" was looking for converting stored energy from somewhere else than body fat.

Or he didn't see that the only way to get BTUs extracted is by energy conversion.

 

[texastee]

I heard a report this morning that 1.8 billion people in the world don't even have electricity.....Maybe it's just a convience that the rest of us could do without.....

 

[Guy_Incognito]

Muscle power:

I remember an old rule: 1/8 HP is what men can do for a longer period.
That makes it about 100 Watts at 100% efficiency.
But I think "guy I" was looking for converting stored energy from somewhere else than body fat.

Or he didn't see that the only way to get BTUs extracted is by energy conversion.

Don't forget, there's a heat pump involved that is more than 100% efficient.
You put in 100 watts , you get to transfer more than 100 watts from one place to another. In the case of a compressor driven system , it's about 3 or 4 hundred percent efficient.

 

[wasabell]

We use a "portable" ice maker. I say "portable" but it weights 46 lbs. It's actually a counter-top ice maker. It cost $179.00 on sale, not iincluding the $30.00 rebate). We bought it at Home Depot. It drops its first load of ice after 20 minutes. And every 20 minutes after that. Supposed to produce 30 or so lbs of ice per day. It only uses 200 watts, so we can run it off the generator.

Its much faster than the frig ice-maker, which died a couple of weeks after we bought this puppy. It probably died of embarrassment.

Here's a link to one just like ours, except ours is silver(colored).

http://www.directron.com/mcim30tw.html

 

[Christian for Israel]

guy, i've posted links to icyball sites a dozen times and believe me, there's very little interest.

here's one of the links i've put up before: http://www.ggw.org/~cac/IcyBall/crosley_icyball.html

 

[tangent]

frm Medtech site:


Vortex tube Refrigeration

http://fab.cba.mit.edu/labs/tti/ttinew/Voretxv1.html

--------
following copied over from another thread: (burried in thread drift...)

> The only sure source of "refrigeration" will be underground storage, i.e. a cellar. So storage temps will run mid-50s to mid 60s F.

there are a couple of peiltzer(sp?) based portable fridges out there that run on 12V w/ a car cig outlet plugin. It comes w/ a big wallwart to mate w/ it, if you want to run it off house current.

Some will hold 18 standard beverage cans (beer/pop), others will just hold a 6 pack. There is no freezer. One I have gets down to 48deg and stays there, but it can take 12 hours to go from room temp to 48 deg. Temp is not ajustable. Shop arround - prices vary for the same unit.

They run in the $50 - $100 range - shop arround. You could probably make something better if you bought the peltzier(s) and built an insulated box arround them. Add a temp guage and a rheastat to control temp.

That alt energy co in Boulder colo had kits and referbs for high efficency and alt energy fridges, washers, etc...

nice thing about peltzier's is they generate heat to - so if you need to culture something...

-t
-----
FERD:
There are also propane fueled (no compressor) coolers that use a small flame to heat freon (or whatever) to expand/condense via convection - these are used in (for example) RV's, and the reason that people have to level their RV's (the flame has a relatively small aperture to burn in).

There are also completely solar powered electric ice chests and freezers, and HomePower magazine had an article earlier this year (I think) on a completely solar no moving parts closed loop convective cooling system. http://www.homepower.com/files/solarice.pdf

Finally, if you live in a cold climate, you can make ice blocks in the winter time (take a plastic trash bag and line a cardboard box. Fill with water, let freeze. Remove ice and bag from box, place ice in 'icehouse' (very highly insulated structure). Repeat box / bag / water / freeze cycle as needed).

I have a very old (now, like 15 years old) 12 v icebox like you mention. It does take quite a long time to cool down (it helps if you pre-chill it with blue ice or something) but mine at least will get down around freezing.

Interesting idea about using one as an incubator. They don't really get that hot, and controling the temp would be easy. Plus, it's a handy size, and could work off of a small solar array (one or two roll-up panels?) and a small gelcell battery (for at night). Hmmmmm
----------
The medtech CD has a document in /medlab/equipment called "how to look after a fridge" about these type of units. Repair and maintenence type material.

-t
==== end forward ====

Somewhere on the board we also have info on evaporative cooling - clay pot and sand and maybe a bit on swamp coolers... I'll see if I can find that and link stuff here.

-t

 

[Charlie]

Rediscovering the Wheel

Geesh.....the Propane Fridges are still out there all over the place. I scored a big kahuna one prior to Y2K and it is on my porch thumping along just fine. The local Amish sell them new gee whiz ones for big bucks, but the old ones are still available if you look.

Now for the new technology. Me be working with my wood boiler provider to hook up my wood boiler to refridgeration. Work in progress with some stuff available now and other stuff in the works. Stay tuned.

 

[Guy_Incognito]

Thanks for the links all. I must confess, I'm interested in the 'from-scratch' type of thing. I like building things from leftover bits. And there are things (like meds, beer, etc) that need to be kept cold.

You can also pull out the old EMP worst-case scenario and wave it about a bit if you like , which is why I'm looking at other alternatives.

Propane/kero fridges are great, if you've got fuel to burn. If the thing I'm building failes miserably, a propane fridge would be the way to go. Until I run out of propane :P

Thermoelectric ones are a bit on the ineffecient side of things, unless you want to build a "hot-and-cold" box.... and the hot side will be pretty warm

You can get 12V compressor upright fridges (of about "small household" size) which are excellent on power usage.... but seem to come platinum-coated, if the list price is anything to go by.

I could probably build an ammonia-cycle cooler like the icyball, using calcium chloride as an absorbant and two fire extinguishers and some misc bits.... except I need ammonia , which is a little tough to get.

But again, thanks for all the alternatives

 

[Christian for Israel]

one of the kero or propane fridges could be converted to wood or even solar if necessary. all that is required is a heat source to operate the convection unit...heck, if the insulation is sufficient all you'd have to do would be to light a small fire for an hour or so a day to keep it cold.

 

[jed turtle]

as to acquiring liquid ammonia ( i inherited a gallon from a fellow that i inherited my office blueprint copier from) i found this refernece via google:

"suitable ammonia is available at large office or printing supply stores (for blueprint copiers).

The actual chemical name you need to find is ammonium hydroxide. We use tons of it in the semiconductor industry for cleaning silicon wafers using what is called the RCA clean aka SC-1, SC-2. VWR Scientific should have it on their website or a local chemical supply store would be a likely source. It's a very strong base and is often used in industry to make basic solutions when the PH needs to be high to get a reaction to occur. Sort of the basic equivalent to sulfuric acid. "

great find on the homepower site, Tangent! looks doable and perfect for the average homesteader who may be 100% employed with homesteading soon...

 

[tangent]

On the ammonia - be careful...

It's A) not pleasent to handle

and, B) IIRC, on the DEA watch list as I believe it's an ingreedient meth cooks use...

(unless of course - you really crave uninvited company at 3am...)

-t

 

[Dobbin]

Actual Ammonia (NH3) is...

...a volatile gas, poisonous, and is kept compressed in cylinders. There is a considerable amount of information about ammonia in the old engineering texts like how to transport and use the cylinders, how to charge an ammonia refrigeration system (done on the "low" side with the gas cylinder upended as I remember it) and the safety precautions required.

And there are a few.

The problems with pure ammonia come about because of it's EXTREME proclivity to combine with water to become NH40H which is the ammonia water we're used to around the laundry room and referenced in the article above. You breath the pure ammonia gas and it combines with the water in your mucous membranes to make ammonia water inside of you. Thus you burn from inside out in caustic reaction.

Even the ammonia smell from ammonia water (which comes about by virtue of a few molecules of NH3 escaping from combination with the water) can be dangerous by this mechanism. The fortunate thing is that human sensitivity to the ammonia smell is similar to a dog's sense of smell of most everything else. We smell, we react to get away long before a dangerous concentration of ammonia water can build up inside us.

One of the band-aid remedies for an ammonia leak in the old time refrigeration system is to play water over the leak. Ammonia gas combines with the water almost instantly and the refrigeration plant can be kept limping along without hazard to the operators. Of course it's better (and cheaper) to solve the leak.

I considered constructing the Homepower solar icemaker and continuing the experimentation started by the Mother Earth News Wood fired refrigerator article but ruled both out due to the problems inherent with pure ammonia. It's just not fun stuff.

Best,
Joe