Path: wn3!worldnet.att.net!howland.erols.net!newsfeed.internetmci.com!in3.uu.net!206.250.118.17!nntp.earthlink.net!usenet From: serfsup@earthlink.net (serfsup) Newsgroups: alt.survival,misc.survivalism Subject: Re: Absorption refrigerator (was Re: help needed with bio-gas generator) Date: Sat, 24 May 1997 15:54:28 GMT Organization: EarthLink Network, Inc. Lines: 92 Message-ID: <33870ee5.3665328@news.earthlink.net> References: <1997051923372076078@zetnet.co.uk> <338190A5.585F@primenet.com> <338428CE.64A8@primenet.com> NNTP-Posting-Host: cust101.max12.cleveland.oh.ms.uu.net X-Newsreader: Forte Free Agent 1.1/32.230 Xref: wn3 alt.survival:1636 misc.survivalism:37625 This does look pretty easy to build. Thanks for pointing it out. On 22 May 1997 04:08:00 -0700, Gene Alan Townsend wrote: >The Lorax wrote: >> >> On 20 May 1997, Gene Alan Townsend wrote: >> >> > The least expensive, and most appropriate means for solar powered >> > refrigeration in the 3rd world countries would be a solar thermal >> > approach using a cheap parabolic reflector, along with an "icy ball" >> > type absorbtion refrigerator, which could be easily made in any high >> > school machine shop. These have no moving parts, containing only two >> > small tanks and some plumbing. One ball is heated by the sun at the >> > point focus of the collector, charging the unit for a few hours in the >> > day time. The unit is then taken inside, placed in an insulated box >> > with the other ball inside, where it will remain cool for 24 hours if >> > designed properly. This device uses an ammonia cycle at 100 to 150 psi, >> > and should be built of iron or stainless steel. >> >> Can you please give some specifics about how to build this, or do you >> have references for books that give detail on it? I've heard of this sort >> of system and would be very interested in building one myself for a small >> home refrigerator that could be powered by solar or recharged by some >> other heat source (perhaps a wood stove) when the sun does not shine >> enough. As I understand it the principle is to evaporate the mixture in >> the ball and then when the ball is placed into the refrigerator box it >> absorbs heat from its surroundings as the mixture condenses back into a >> liquid. What exactly is the mixture in the ball? I've seen it refered to >> as an amonia absorption cycle but is it straight amonia in the ball? Can >> other chemicals be used? I know amonia fumes can be dangerouse if the >> apparatus leaks vapors into the living space. >> >> >> St. Paul, Minnesota >> > >I've seen references to the "icy Ball" in several older refrigeration >text books. However, no details on building one. Should be fairly >simple, as long as one exercises some care in the design. > >It is basically two flasks, connected at the top with an inverted >U-shaped tube. One flask contains a saturated ammonia-water solution, >which can be purchased at your local blue print supply company as "Diazo >Developer". The other flask is initially empty. There is no need to >purge air from the system before filling with ammonia solution. > >The flasks and tubing should be stainless steel, but black iron pipe may >be adequate. > >There will need to be an opening for filling with solution, and a >temperature and pressure gauge would be helpful. > >Before charging, be sure all the solution is in the larger of the two >flasks, which I will call the "solution flask". This will need to be >about twice the volume of the other flask, which I will call the >"ammonia flask". During charging, heat is applied to the solution >flask, while the ammonia flask is placed in a bucket of water. The U >must be upside down. As the solution is heated, ammonia gas will >de-sorb from solution, raising the pressure in the system to about 100 >psi. This should happen at a temperature of around 250 deg. F. The >ammonia gas will condense to liquid ammonia in the ammonia flask. When >all the ammonia is desorbed, the charging is complete, and the unit must >be removed from the heat, otherwise, the remaining water in the solution >tank will boil, creating a dangerous situation. > >In use, the smaller ammonia flask is placed inside an insulated box, >while the larger solution flask, now containing only water is placed >outside the box in ambient air. As the ammonia boils, it will extract >heat from the box, becoming icy, hence the name "icy ball". When the >gas reaches the water, it will sorb into it, making the solution hot. >The ambient air will cool the solution tank, completing the loop. When >all the ammonia has evaporated, the process must be repeated again. >With proper design, daily charging should be possible. > > >Be careful. An explosion containing ammonia can be very dangerous. >Work outside in well ventilated area until confidence established. I >would measure at least the temperature of the solution flask to be sure >the temperature never exceeds 250 deg. F during charging. This is well >below the boiling point for water at 150 psi. > >I think it would be possible to build one of these using black iron pipe >and fittings. > >I would suggest using fairly large diameter, say 4 in., for both flasks. > >Regards, > >Gene A. Townsend