Posted: 7/9/2005 9:44:43 PM EDT
| Or R134 for that matter? Why cant you run and air conditioner with nitrogen or argon? |
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"FREON" is a brand name... like calling all AR-15's, Colts (YUCK) R-12 "Freon" was DuPont made. is actually a refrigerant. I know (DUHHHH!) R134a is a refrigerant as well as "Ammonia" is... Yes.. Ammonia... at least you always know when you have a leak. PEE-EEEEEEEEEW!!!!! R134a is not as bad as I thought it was... at first they told us when ever you have a refrigerant leak in a R134a system you MUST change the compressor... not true. Ammonia is used mainly in chiller systems nowadays. No thanks... not for me. |
How about Propane, the poor mans R-12. |
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... The banning of R-12 falls in the same Bullshit category as "asbestos" dust "contamination" and "mold" epidemic (in Az no less!) in real estate purchases- This ain't what's killing us folks. ... Unabated tort lawsuits makes us all suffer the consequences for years for these herringbone, precedent setting BS cases. ... This is a fundamental reason we should all promote the Conservatives cause IMO |
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It's thier boiling points. For instance R-12 has a boiling point of -21degrees F @ 1 atmosphere of pressure. Pressure controlls the boiling point. Go from a controlled high pressure liquid, Example 250 lbs through a valve to a pressure of 30 lbs and now you've a very cold gas. Thats how the stuff works in simple terms. |
| Yeah, different materials take different amounts of heat to do the phase change between gas and liquid and back again. You also want it to change phase at a reasonable pressure. The phase change is very important, since that can transport a lot of heat compared to a material that stays only in one state. |
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Why Freon? Because it has reasonable vapor pressure, is non-flammable and is relatively inert/non toxic. Ammonia isn't inert, is flammable and quite annoying at low concentrations...lethal at appreciable levels. Propane/butane is flammable. Nitrogen/argon have pressures that are far too high and temperatures WAY too low. They are used in cryogenic refrigerators but that would be far too inefficient. Water is about the only refrigerant that is safer than Freons BUT its vapor pressure at reasonable temperatures makes refrigeration highly inefficient unless absorption is the means. A liquid absorbant "grabs" the vapor, allowing for the pressure differential of ~1 PSIA. The water is removed from the absorbant at the higher pressure by heating the water/absorbant mixture. The steam is then condensed at a temperature of about 150 F, producing liquid water which goes back to the evaporator (the part that gets cold). The water evaporates at 34 F at a pressure of about 0.001 PSIA and the cycle continues...the absorbant must also be cooled to about 100F or cooler before it returns to the absorber section. This is a simple explaination of absorption refrigeration. Very little mechanical/electrical power is needed, only a source of heat and somewhere to dump a bit more heat. Subs use this system as waste heat from the reactors is abundant, the outside water is a great place to dump this heat and the system is very quiet. Elsewhere, mechanical power is far cheaper for refrigeration than what it costs to maintain the system. The main problem is tiny leaks kill the system since any air increases the pressure and dramatically decreases the rate of absorption. Absorbant is usually lithium bromide, a salt that absorbs water to form a heavy solution. This solution can absorb even more water vapor. How do I know this? I built such a system. 1/10th a ton. It worked and got me an A in Mechanical Engineering Senior Design. 5 heat exchangers, 3 pressure vessels operating at near perfect vacuum, a heat-powered liquid pump capable of the 1 PSI pressure differential and scads of stainless steel. Lithium bromide is a corrosive salt. |
Natural gas refrigeration is comercially available either using gas fired motors or absorption cooling. I remember seeing an offer from the localgas company for a gas fired air conditioner once. www.ugi.com/gas/bus2d-1.htm Another absorption refrigerator that was popular in the early twentieth century was the Crosley Icy Ball. You heated one ball for 90 minute over a fire, the other ball would get cold and provide cooling for 24 hours or more. www.ggw.org/~cac/IcyBall/crosley_icyball.html   Seems like Natural gas may have an advantage for a large business that relies heavily on refrigeration, like a supermarket (have seen mass quantities of dry ice purchased durring power outages) or a food proccessor... |
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Icyballs use ammonia, a great refrigerant except for its nasty chemical properties. The only issue with LiBr units is the low pressure (vacuum) and corrosive nature of this salt. When looking through the Google links, I found another environmental do-gooder who got it wrong about HFC's....called them hydrochloro[/]fluorocarbons. WRONG! HCFCs are but HFCs are hydrofluorocarbons. R134a is an HFC... It is called the rule of 90 for refrigerants. Covers HFC, CFC and HCFC types. You take the refrigerant number (R12, R134 etc) and add 90. This number is a code of the composition. The first is the # of carbon atoms per refrigerant molecule. For R12, 12 + 90 = 102 and it has one carbon atom. The second number is the number of hydrogen atoms. R12 has no hydrogen but R134a has 2. The third number is the number of fluorine atoms. |
I am amazed at the knowledge base of this group. Amazing at every turn.  The stuff that destroys the ozone layer (I call BS on that as well) is R-12. I remember paying 30.00 for a 30 lb jug of it. NOW the same 30 lb jug is going for 1200.00 ... If I only knew then what I know now, I would have bought PALLETS of them.  I did ask a college professor once who taught enviormental science, how long would it take for R-12 (cfc) to reach the ozone layer if released today. he said about 50 years... my next question baffled him. "If it takes 50 years for CFC's to reach the ozone layer, please explain to me how then that R12 is causing the hole whene there was no R12 50 years ago?" He had no explanation. Then when I asked "When we as an industry let out a ton of CFC and the oceans and volcanoes naturally emit MEGA tons of natural CFC in the air... we are just a drop in the bucket right?" his answer was "Well, we all have to do our part" 
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Oh, he missed the BIG part. Sure, ClO will act as a catalyst to decompose O3 BUT the whole concept of ozone blockin UV is absurd to the point of insanity. How so? Faulty cause and effect. First of all, ozone is MADE by the action of UV on OXYGEN. Ozone itself is thermodynamically unstable and will decompose faster if exposed to more UV. Ergo, the ozone layer is a product of oxygen blocking UV, not a UV blocking mechanism itself. Ozone in the upper atmosphere has a half life of a matter of seconds, even without ClO. More ozone just means shorter half life. Ozone is a much larger molecule than oxygen so how can a larger molecule block a shorter wavelength? Pure BS. Think I am pulling this out of my ass? Take a trip to the Dead Sea. There, even the lightest skinned person WILL NOT SUNBURN. This is due to the extra 1250 feet of atmosphere, every single foot of it very low in ozone but rich in oxygen. And the kicker is the third world produces just as much Cl2C2F2 (R12) as before the Montreal Protocol. |