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dude
01-03-2004, 02:28 AM
Is there anything about R134a that is superior to R12 excluding the ability to satisfy the regulations and a relatively low cost of R134a only as a result of government regulations causing R12 price increase?



Relative to R12, R134a:

Sucks because:
Mixture of R134a and its lubricant has affinity for water.

The mixture don't get along with capillary tube as well as R12+mineral oil mixture.

Havea greater potentional of causing a cardiac arrhythmias.

Mixture of R134a+air can ignite under pressure.

If not of government bureaucracy and consequential scarcity increasing the price of R12, R134a costs more.

Higher head pressure, more stress on the compressor, higher leak rate.

Thermodynamic properties that are less desirable than R12.

It doesn't like high condenser temperature.

Rules because:
um.... I don't know.



.....

Does R134a really save the environment compared to R12 used in a responsible manner?

baker
01-03-2004, 03:09 AM
[i]
Does R134a really save the environment compared to R12 used in a responsible manner? [/B]

I would defy anyone to show how R12 used in hermetic systems following best practice could have any significant impact upon the ozone layer.

Clearly, its use as an aerosol propellant, foam blower and in inherently leak-prone car systems had to be curtailed. I can see no reason why its use in hermetically sealed refrigeration units can't continue - except that it will never happen.

Too many people, including most politicians, don't like complexity. Like DDT, CFCs have now been declared "bad". In reality, it is overuse and improper use that is bad. The chemicals themselves have their place and usefulness if used responsibly.

I believe that a good economic case could be made for the use of R12 in hermetic systems. I don't see any financial rewards for making this case, though, and do not expect it to ever happen. The Europeans are happily using R600a in domestic refrigerators, and I believe this to be better than R134a.

shogun7
01-03-2004, 07:33 AM
According to scientific research, a breakdown of CFC in the upper stratosphere results in the following sequence of events:

• Step 01- CFCs are broken down in to Chlorine and Dichlorofluoromethane by the UV rays.
• Step 02- Ozone molecules are broken down in to oxygen (O2) and Chlorine monoxide (ClO) by these Chlorine atoms. This process reduces the Ozone (O3) in the stratosphere.
• Step 03- a free oxygen atom reacts with chlorine monoxide and a chlorine atom is set free. Repetition of this process gradually thins out the Ozone layer.

All refrigerants have some downside to them. The key is to find the best products. Carbon dioxide was one refrigerant discussed at a recent conference. Strange, because carbon dioxide is one of the main contributors to global warming. Charles Bullock, an engineer with Carrier Corp., said carbon dioxide once was a popular refrigerant. Today, its benefits are low flammability, ODP, cost and low toxicity. But besides its global warming potential, it's inefficient.

"Carbon dioxide (R-744) has several attractive attributes, but its inherently low refrigerating cycle efficiency and high operating pressures will remain serious challenges to use in unitary heating and cooling products in the near term.
It has been proven both in the laboratory and in the real world that chlorine destroys ozone. At one time there was a fear that R-134a might not be as ozone friendly as originally determined but that fear has been proven to be unfounded. While ozone levels continue to decrease, the march toward fixing the problem is making progress. Global warming, or the greenhouse effect, such as increases in carbon dioxide have been cited as the main culprit, which primarily comes from auto, factory and energy plant emissions through the use of fossil fuels such as coal, oil and natural gas.
The deforestation in the tropics is seen as another key to higher carbon dioxide matter in the atmosphere. Propane of course is a HC and as such hydrocarbons are flammable refrigerants, which makes their marketability in the litigation-prone U.S. difficult at best. In Europe, however, it’s predicted the share of refrigerators with hydrocarbon refrigerants will continue to grow, and the foaming will be done completely with hydrocarbons as well.
Hydrocarbon use in unitary air-conditioning systems is unknown at this point because the final draft of Standard EN 378 (a European standard) does not allow its use, at least to my knowledge, I may stand corrected on this. Chillers with hydrocarbon refrigerants were introduced.
Roger

chemi-cool
01-03-2004, 02:23 PM
hi roger,
I agree with what you have written, but one vary important question is missing: what are the quatities of CFC or HCFC that will damage the ozone?

are only the refrigerants to blame?
what about all the methane produced by millions of sheep in AU and NZ?

we have discused this subject a while ago and it didnt go too far,
numbers, is what I want to see not the theory of what it does.

can you get them?

chemi :confused:

shogun7
01-03-2004, 10:54 PM
Hi Chemi
Yes you are right, methane produced by bovines, sheep and the like are a major source of CO2 in addition with regards to ozone depletion problems, Volcanos are also a major contributer, that and with what man contributes is the situation .I have read that at the present rate, i f we would stop depleating the ocone produced it would be 2045 before we would see some major improvements. however we are making progress even if ever so slitely.:rolleyes: :D

shogun7
01-03-2004, 10:59 PM
Hi Chmei

This may give you what you asked for:

Animal waste includes livestock and poultry manure, litter and bedding, dairy parlor waste water, feedlot runoff, silage juices from silos and wasted feed.

If managed properly, animal waste reduces the need for commercial fertilizer. Animal waste adds organic matter to soil and improves the water holding capacity within the soil.

Two trillion pounds of animal waste are produced in the U.S. each year. Intensive livestock operations are the cause of this large amount. These large farms serve as more of a factory than a farm. Although this practice of large intensive farming is dangerous to our drinking water and soils, it can also serve as an alternative energy source in the future. To give you an amount produced in the various states go HERE"
http://www.scorecard.org/env-releases/aw/

Roger