I know they make refridgerators that run on propaine as well as k2 and that they somehow use a small flame to do the cooling like what is in a lot of RVs and such but I dont understand all the workings of them. I was wondering if anyone here knew enouph about them to know how they work and how realistic it would be to build refridgeration that would use the same principals if SHTF. I figured if it can be done with these fuels then it may be able to also be done with wood or tallow or some such. Seems to me that if someone could figure out how to do this and make it work well for something like a walk in size cooler, especialy if it could freeze ice, they could be extreamely popular if SHTF. How much would a glass of iced tea or ice cream be worth on a summer day when its over 100 out when no one has ice, refridgeration or air conditioning anymore? Not to mention being able to cool and store fresh meats and milk and so on rather than haveing to can all of the stuff or use it and use it warm right away.
If you really want it, I'll dig out the thermodynamics book and pass along the theory. For now, suffice it to say it is a hell of a lot easier and cheaper to buy one than to build one. And more likely to work as well. Yes, they work, and work well, but no where near as inexpensively as an electric unit. That said, they are designed to be used where there is no electricity, and could serve as a backup for small needs like meds and some limited ice making. A cold room would be incredibly expensive to run, the room itself would be easy. You are surely crafty and ceative enough to build it, but some of the materials will take real care in selection and sizing.
IIRC, doesn't this type system run on a similiar method to conventional refridgeration? Ie force a gas through a small hole (orfice) and it gets cold? Not sure that wood or tallow could be made to work in this respect.
'Fraid not. The simple cycle you mention requires some sort of mechanical input to compress the refrigerant gas (then cool it to condense) so that you can expand it thru the orifice (thereby lowering the temperature.) The propane (and other heat source devices depend on an absorption of one material by another, then differentially boiling one off under a closed system gravity head. There are no moving parts in the household machines, but in the really big absorption chillers, there are pumps involved requiring power anyway. Fact is, absorption machines make no economic sense at all unless there is waste heat from another process available on site and power available to drive the pumps. If you could sort out the control scheme and get the right proportions of carrier, absorber, and refrigerant fluids in the right configuration, tallow and wood could be used as fuel, but not in the thermodynamic cycle. Sorry, this is bad news for the hobbyist and usual survivalist. BUT (and it's a big but) if you can be assured of a supply of propane or K2, a gas driven fridge is a good idea for bug inners, or for those with a good sized vehicle for the fuel and machinery. Bear in mind that you will need to hide the fact that you have assets of this nature, because if you don't there will be visitors. Cold is going to become as valuable in summer as heat in the winter. Diabetics, take note, and those in freezing climates, figure out where to put your ice house and start saving sawdust. You are going to trade for beans and bacon.
http://home.howstuffworks.com/refrigerator5.htm bottom of page: http://www.backwoodssolar.com/Catalogpages2/refriger2.htm
Please do pass along the theory. I'm working at an all mechanical shop these days rather than just a plumbing shop. I'll be taking some classes in the near future on boilers, pressure vessels, heating and refrigeration. We do the dry and wet side of heating , AC, boilers, firesprinklers (wet and dry systems), plumbing. Oh yeah, you can blame me for all the Unread Posts you were speaking about in the Shoutbox. http://survivalmonkey.com/forum/showpost.php?p=29414&postcount=33
Yup, I haven't done any boiler, hydronic heat or refrigeration yet, soon enough. A couple weeks ago we completed a large warehouse firesprinkler project. Better yet, I'm driving to Salem instead of Portland. Traffic isn't even an issue anymore, nice commute.
More primers on the subject. The thermodynamics is easy (according to my profs, but I didn't get a grip on it worth having.) Messing with a 210 T LiBr plant in the Navy pretty well convinced me that the theory was the easy part. Keeping that sucker running was not a trivial task, especially in a seaway. It was sensitive to level, pressure and load. The cycle used lithium bromide rather than ammonia. I believe the LiBr plants are safer in many ways than ammonia, but more expensive. Both type MUST be leak tight or people die, but at least with LiBr you get a chance to run. These have to run under a high vacuum, and the absorption cycle will get you there, but it takes a while to light off and stabilize. Both types work, and work well under steady or slowly changing load. Ammonia plants are more tolerant of load fluctuations, if I remember rightly. It's been a while, I've grown to like conventional compressor plants. http://www.limsi.fr/Individu/mpons/pricyc.htm http://geoheat.oit.edu/bulletin/bull19-1/art62.htm http://www.nh3tech.org/absorption.html Enjoy the reading. I'll try to dig up my old physics text and scan in some of the thermodynamics if you really survive the simplified explanations.
Thanks for the links, pretty simplified explanations of how refrigeration works and what types of equipment, piping and appurtenances are needed.
my dad and I salvaged a propane fridge out of an old travel trailer that was going to be scraped use it at deer camp a lot works pretty good
They are complicated systems to home build. Even the new ones use a lot of propane (and I suppose) K2. Like Q Sharps, I have been thinking about icehouses. The new foam insulations, like blue or pinkboard or stryrofoam are waterproof and have R values of 4 and 5 per inch respectively. I am wondering about an underground, or even small in basement icehouse/box with like 10 plus inches of insulation. They used to just use sawdust - dirty, suseptable to fire and low insulation value.
