R22 or134A

[Break7]

I tried this question earlier but I think I put it in the wrong spot so I'll try again. Hi I am brand new to RE. Im very interested in HVACR but haven't started yet. I've been reading everything I can. I have a lot of questions. I'm hoping some of you can answer for me. Why is it that window air conditioners are R22 and not 134A? Ive always assumed that 134A is in cars and home friges because they are most likely to get a leak from accidents and non professional tinkering. And134A is considered safe for the environment.

[josei]

Hi. I found the following explanation about your question,

Regards
Josei Melo.
Ashrae A.Member

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R-134a

R-134a is the first non-ozone-depleting fluorocarbon
refrigerant to be commercialized. Developed more
than 20 years ago to have characteristics similar to
R-12, it is a viable candidate for use in medium- and
high-temperature applications in which R-12 has been
used. R-134a has been generally accepted by the
automotive air conditioning industry because of its
low hose permeability and high critical temperature.
Domestic refrigerator producers also find R-134a to
be a viable refrigerant for their products. R-134a is
available from most refrigerant manufacturers.
R-134a has the benefit of being a single-component
refrigerant and, therefore, does not have any glide. In
addition, the direct HGWP of R-134a is low, relative
to other options that have been evaluated.

The disadvantage of R-134a lies in its relatively low
capacity compared to R-22. To utilize this refrigerant,
all of the tubing within the heat exchangers and
between the components of a system would need to
be significantly larger to minimize pressure drops and
maintain an acceptable operating efficiency. This,
combined with the greater compressor displacements
required, results in a system that will be more costly
than R-22 systems today. The heat-transfer coefficient
of R-134a is also lower than that of R-22, and tests
show that system performance degrades with its use.
In summary, manufacturers would need to invest
significant time and capital to redesign refrigeration
systems from R-22 to R-134a and ultimately would have
a design with inherently lower performance or higher
cost; therefore, for residential and smaller commercial
systems in which R-22 has traditionally been used, we
feel R-134a is the least likely HFC candidate.

With the exception of ozone-depletion potential,
Emerson* believes that R-134a possesses the same
deficiencies as R-12 and represents a step backward
for most commercial refrigeration and air conditioning "

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From: Refrigerants for Commercial
Refrigeration Applications
May 2008 (site:emersonclimate.com/images/5683-RefrigerantWhtPaper_9.pdf)
-----------------------------------------------------
*About Emerson Climate Technologies, Inc.
Emerson Climate Technologies, Inc., part of
Emerson Climate Technologies,is the world’s
leading compressor manufacturer,offering more
than 10,000 compressor models in a full range of technologies,
including scroll, reciprocating and screw compressor designs.
for most commercial refrigeration and air conditioning

[Break7]

Thankyou for your reply and your time I greatly apreciate it

[Brian_UK]

Great answer above and I suppose we could also say that R22 got there first

[josei]

Great answer above and I suppose we could also say that R22 got there first

I appreciate your words. The question then is : R22 or which ?.

From the same source i can take this words:
"R-410A is one of the most important HFC refrigerants
helping the industry meet the 2010 deadline.
Ample research has shown that R-410A is the best
replacement for R-22 refrigerants in high-temperature
systems — and manufacturers agree. Most major
residential air conditioning manufacturers already offer
R-410A product lines.

With new residential energyefficiency regulations going into effect in 2006, significantly more air conditioning manufacturers will have implemented the transition to more energyefficient units, using R-410A.

R-410A has quickly become the refrigerant of choice
for use in residential air conditioning applications,
because the refrigerant delivers higher efficiency and
better TEWI than other choices. The refrigerant also
has many benefits that make it an ideal refrigerant for
use in commercial refrigeration applications.

There are several distinct operational differences
between R-22 and R-410A refrigerants. R-410A
operates at 50 percent higher pressure than R-22;
however, the higher pressure allows the system to
actually run at a lower temperature. Because of these
differences, anyone handling these units should receive training on the technical aspects of the new R-410A systems, where they can learn proper joint brazing and critical maintenance tips for this new refrigerant.

R-410A is a near-azeotrope composition of 50 percent
R-32 and 50 percent R-125. To date, optimized system
testing has shown that R-410A delivers higher system
efficiency than R-22. R-410A evaporates with a
35 percent higher heat-transfer coefficient and
28 percent lower pressure drop compared to R-22.

Additional system performance enhancements have
been gained by sizing for equal pressure drop and
reducing the number of coil circuits needed to increase
the mass flux. The higher density and pressure also
permit the use of smaller-diameter tubing, while
maintaining reasonable pressure drops.

Because systems that use R-410A have been specially
designed to use less tubing and fewer coils, R-410A
has emerged as a very cost-effective refrigerant.
Fewer materials, along with reduced refrigerant
charge and better cyclic performance, also contribute
to the affordability of R-410A.

R-410A is considered a very high-pressure refrigerant.Very high-pressure refrigerants operate at pressures significantly higher than those normally seen with refrigerants such as R-22 and R-502. They cannot be used as retrofit refrigerants with existing equipment, but only in new equipment (including compressors) specifically designed for them.
Existing R-22 compressors cannot meet UL and industry design standards with
these higher pressures.

For refrigeration application, R-410A is potentially the
most efficient refrigerant at medium-temperature
conditions (zero to 30 degrees Fahrenheit). Additional
advantages include reduced line sizes and lower
pressure drops; however, the system would require
design for higher pressures. Potential changes in UL
requirements may reduce the impact. Testing at lower
temperatures has shown promising results. Research
is ongoing at Emerson to understand the benefits "

[Brian_UK]

The question then is : R22 or which ?

I'm sorry, I don't understand your question.

[josei]

Ok. Which is the best replacement for R-22 refrigerant ?

[Brian_UK]

If you are planning a retrofit then use one of the 'drop-in' replacements.

If a new system design then use R410a.