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If you want to make just enough ice to put in an icebox to keep food cool, you need to make it in block form rather then small chunks, it thaws slower that way.
All the above being said, if you hook a rotary vacuum pump to a bicycle that hooks to a strong walled vessel mostly full of water(less air to pump before it starts to boil) you can pedal at a leisurly pace for 30 minutes to an hour and get about a gallon of Ice to sit in your ice box. More water to freeze= more pedaling, higher water temp=more pedaling, small moving volume pump=more pedaling.
Hook pump to a decent water wheel on a good grade stream or a good sized windmill (enough to overcome torque) and voila. All this with no exotic solutions. make multiple vaccu-tainers with water and swap out when one ices up.
You only have to have a strong/expensive enough vacuum to make the water boil, once it starts boiling the pressure can, if you want, stay the same in the chamber due to vapor expansion leveling out the vacuum. A pump rated just enough to reach that point vacuum with a large moving volume will work but if you want to do it quickly you want a vacuum pump that can remove the expanded water vapor much faster than it is created to get faster boils/higher vacuums and thus less pedal, water wheel or windmill ice generation time.
Make your water ice cooling chamber easily disconnectable from the pump and place it directly in the icebox. That is unless you want ice cubes, lol.
Do you have any more detailed plans you can share of the one you built or someone who has built a similar one? We have a children's home in the jungles of Belize and would like to see if we could build one. Thank you for your help.
http://techref.massmind.org/techref/other/zeolitefridg.htm
Any ideas?
I have yet to come upon the most effective sterling design that I could manage cost effectively, but I am looking at such designs for a larger power plan than just a freezer now.
I was interested in figuring out a design that might get away with using basic thermodynamic principles and heat transfer to create the ice here.
I figure if the energy doesn't have to be converted it should be more efficient.
I understand the principles, it's putting them into design that seems to have me stumped at the moment.
(Pardon the late response, it's been a busy few years. lol)
http://www.appropedia.org/UTC_Solar_Absorption_Refrigeration
and download this file from there:
Study, Design and Fabrication of a Solar Powered Adsorption Refrigeration System
It takes energy to make ice, the sun is a source of energy. The rest is engineering.
Heh. Bud, if everyone felt sorry every time they did something stupid, the entire nation would have to be on prozac to get anything done. Don't worry about it.
http://www.solarhaven.org/AmmoniaAbsorptionIcemaker.pdf
Apparently all you need is a refrigerant such as (distilled!) ammonia, dissolved in salt, in the "generator" of the sealed system (the "generator" is where the sun heats the solution). The PDF calls specifically for calcium chloride. As the sun heats up the solution, pressure in the system increases. The ammonia escapes in vapor form and travels through condenser coils to a containment tank (which will soon be very cold). When the generator no longer receives heat, the system cannot maintain the vapor ammonia, and it is "drawn" back to the generator component as the salt reabsorbs it. This absorption lowers the pressure of the system, causing the ammonia in the tank to evaporate, drawing immense amounts of heat with it. Water is placed close to the tank and loses all its heat - voila: ice!
Part 2: Use mechanical energy to drive an automotive air conditioning compressor. If you are careful you can liberate all you need off an old car, then build a styrofoam box for the core that was inside the cabin giving off the cold, mount everything and hook it back up, refill. Make cold.
Now when you consider the mechanical energy required when driven by a car engine, both the amount needed and the rate it must be delivered to the compressor, you can see the amount of solar-absorbing surface area needed, ballpark figures, is a softball field.
Or...
You set up some photovoltaic panels, add a good-sized battery and inverter for homebrewed solar-based electricity, and plug in the refrigerator or air conditioner.
Ah, and now I see why there are no 'ibles on solar ice makers. That'd be a single-purpose dedicated system, they prefer flexible designing around here. With the solar electric you can also recharge your iPod.
(A quick eBay search later) eBay has several machines dedicated solely to producing ice: this model is rated at 310 watts; here is a 150-watt model. Now that I think about it, you won't be wanting to make ice cubes 24/7, right? This could be simpler than I thought earlier... At 20 Ah (240 Watt-hours), our heavy duty car battery would give the inverter just enough juice to power the 150-watt model for about an hour and a half. According to the stats, that's probably enough to make around 2 pounds of ice. :-) Add another battery, and you can get 4 pounds.
Whoa, now here at eBay-Australia they have 1050 Ah batteries for a solar system! Makes these common 86.4 Ah ones look puny.
1050 Ah... You could power an electric submarine with those babies...
Still... What's missing in my previous thought? How many watt-hours do solar homes use? For that matter, how many would a simple ice machine use? (I am now assuming one would not want to make ice 24 hours a day...)
Perhaps, do inverters change the rate by which power is drained from their sources?
That's somewhat easy. A dorm cube has a simple mechanical thermostat, only the compressor uses power. Once you get to a refrigerator / freezer, at the least they have a small heating element on the front between the two sections, you can feel the warmth on that surface the doors seal against, iirc it's to prevent condensation. I've found them on freezer-over-fridge, don't know about others but I'd suspect the same. Then there is the circulating fan, I can see that they'd have models that'd run the fan to cool the fridge from existing cold in the freezer without turning on the compressor until the freezer needed it, although with the old models I'm familiar with the thermostat is in the fridge and the freezer uses airflow controls, compressor and fan turn on together. Finally we get to automatic ice makers, standby losses with electronics, and the ultra-fancy drink and sushi dispensers, whatever they toss in these days.
1) How often, and for how long, on average, do fridges run?
That's math. Take the nameplate ratings for amperage and/or wattage, that's the maximum running amounts electricians need to know to size a dedicated circuit. Then see what the big energy use sticker gives for annual usage, been awhile since I studied one, if they don't outright say how many watt-hours then you can calculate it from the operating cost divided by the cost per kWh given. Divide by hours in a year for average watts per day, divide that by nameplate wattage and multiply by 100 for estimated percentage of run time during a day.
Heh. My parent's fridge I bought used as a quick replacement almost twenty years ago. It's a Kelvinator, made by AMC, thus old. It refuses to die. The hot coils are under the outside skin, no cleaning. There is no fan, no air movement between freezer and fridge. The freezer has the most coils, under its skin so only the sheet metal ices up, the fridge has a small coil section around three sides at the top for cooling with a drip tray running under it. Only thing running is the compressor, thermostat is mechanical, you can hardly hear it running, it just sits there and makes cold. I cannot see how anything of comparable size on the market today will save energy over such a simple and efficient design.