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Old 03-05-2015, 11:02 AM
chrisser Male chrisser is offline
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Default Winter refrigeration

Been trying to decide between an electric and propane fridge has had me thinking about refrigeration.

It occurred to me that, when it's cold outside, it's a little bit silly to warm the house, and then cool the fridge back to the temp it already is outside.

Seems there ought to be some way to build a small heat exchanger that would take advantage of the outdoor temps to keep the fridge cold essentially for free.

Wondering if some copper coils with antifreeze, one inside the fridge and one outside the house might work as a heat exchanger. Or would you need to use a refrigerant to get any sort of useful heat flow?

Or maybe you could boost the efficiency of a fridge by insulating the sides of the fridge to keep the heat in the house, and then expose the rear coils to cooler outside air - that's how our RV works and I've added fans to improve the cooling in the summer. This might even boost efficiency in the summertime if you got some airflow on those coils rather than confining them behind the fridge against a wall as is usually done.

Any thoughts?
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Old 03-05-2015, 12:38 PM
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coaltrain Male coaltrain is offline
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I think about this all the time. Standing in the warm kitchen listening to the refrigerator run while looking out the window at all the free cold air.
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Old 03-05-2015, 01:31 PM
CrossRoads Female CrossRoads is offline
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I don't have any technical thoughts on this subject.

Just my observation of what goes on in our garage. The freezer is out there, so cold in the winter. Cool in the summer. It's a garage with metal sides and metal roof that we physically built ourselves. A few years ago, I got a small refrigerator to use for the overflow of eggs from our chickens. Well this winter because we had the coldest February on record in over 100 years for our area, well that refrig became a freezer. I had frozen eggs. No adjustments that I made would work. So I had to bring my extra eggs inside to the house frig.

I had to do some rearranging in the freezer late last fall. I moved the suet fat for the wild birds over to a cooler. So no cooling system except for the cold outside temperatures.
I could have put a frozen water bottle in the cooler but I didn't. I left the suet in the cooler all winter. It worked out okay.
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Old 03-05-2015, 04:07 PM
Setanta Male Setanta is offline
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I live without refrigeration, didn't want to depend on propane and don't generate enough electric. a few people offered me old refrigerators, a friend gave me an old ciggarette lighter dc icebox, but i don't use it.

in summer i keep things cool by keeping them in a cooler under the cabin, shaded and cool but not cold. in the winter i have a spot in the north side of the cabin near the floor where it is always cold so i built an insulated box with no bottom and put food in there, stays about 40 to 45 degrees inside that spot.
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Old 03-05-2015, 05:44 PM
Doninalaska Doninalaska is offline
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Cold cellar for a fridge. Some of the homesteaders here use a hole dug into the floor of the crawlspace under the cabin. We used to use a wooden box outside as a freezer, but this winter has been too warm here, so the garage freezers have been running all winter.
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Old 03-05-2015, 06:35 PM
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Quote:
Originally Posted by chrisser View Post
Been trying to decide between an electric and propane fridge has had me thinking about refrigeration.

It occurred to me that, when it's cold outside, it's a little bit silly to warm the house, and then cool the fridge back to the temp it already is outside.

Seems there ought to be some way to build a small heat exchanger that would take advantage of the outdoor temps to keep the fridge cold essentially for free.

Wondering if some copper coils with antifreeze, one inside the fridge and one outside the house might work as a heat exchanger. Or would you need to use a refrigerant to get any sort of useful heat flow?

Or maybe you could boost the efficiency of a fridge by insulating the sides of the fridge to keep the heat in the house, and then expose the rear coils to cooler outside air - that's how our RV works and I've added fans to improve the cooling in the summer. This might even boost efficiency in the summertime if you got some airflow on those coils rather than confining them behind the fridge against a wall as is usually done.

Any thoughts?
The coil inside & outside solution would require either a circulating pump or a "heat siphon" set up. But as long as you're drilling holes in your walls, why not just go even lower tech and have a hollow pipe connecting the inside of the fridge to the outside?

The efficiency of any heat exchange engine is directly related to the difference in the temps of the hot & cold reservoirs, so a fridge motor actually has more work to do to cool a fridge when the ambient temp is cooler than when warmer. Of course, when warmer, the insulation of the cold reservoir is less efficient. My freezer in the unheated, uninsulated garage keeps stuff frozen harder in summer than in winter.
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Old 03-06-2015, 07:13 PM
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CarolAnn Female CarolAnn is offline
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I just used a search engine to try to find where I read this, but had no luck. There was an early refrigerator that had a cooling unit that looked kind of like a barbell - two round balls connected by a short pipe. One end went into the fridge back and the other was outside, where you'd put a heat source (like a candle flame) to it to expand the gas and create cooling. Every so often you have to switch ends and repeat.

What I did find was lots of stuff about a planned wood-head fridge. 20 minutes of heat = 24 hours of cooling, which is fine, if you never leave home for more than a day, so that's still a problem.

Using the outside cold, you could simply fill containers of water and make it like an old-fashioned ice box - freeze 'em and put them into the insulated box with your stuff. That would prevent total freezing on days like we've had this week when it dips to -10 degrees.

The real problem of using the outside temperature is especially present in the spring; today it's zero, tomorrow it's 60. that's warm enough to brew some serious bacteria in the leftover chicken! Unless you can freeze huge amounts of ice and pack it away for storage like they used to (below-ground, insulated with lots of sawdust)- maybe that would work.
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Old 03-13-2015, 01:12 AM
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lraude Female lraude is offline
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Try looking at Marine solutions for refrigeration. I had been thinking of living on a sail-boat, until horses and dogs got in the way. But I remember reading about different ways of keeping food cold or frozen even if in the tropics from marine store catalogs (mostly West Marine). might help with your problem. Actually the folks living on sail boats had a LOT of interesting ways of dealing with everyday problems that would work very well off-grid.
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Old 10-22-2015, 10:14 PM
Wanderer Wanderer is offline
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If you're putting energy into the refrigerator, you're generating heat. If the refrigerator is inside, you're heating the house. If the refrigerator is outside, you're heating the outside. If you put the cold box part in the house and the hot coil part outside the house, you're cooling the air inside the house while heating the outside air. You don't want to do that in the winter. If you put the cold box outside and the heat part inside, the cold air outside will help cool the box, while the heat coil will help heat the house. That would cause the refrigerator to run less.

Now, if you were using a peltier thermal electric cooler there might be some efficiency gains from cooling the heat coil but not enough to counter the losses from the insulation of the box or the waste of heating the outdoors. With a refrigerator most of the energy goes to running the compressor.

If you want to get the heat of the coil away from the cold box, you could have some fans blow on the coil and spread the heat around the house. Get some computer fans and a power supply. That would be a lot cheaper and a lot less work.
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