Reference - Mitsubishi Heavy Industries SRK63ZR-WF Technical Manual

16. REFERENCE

(1) Outline
1-1) R32 as the alternative refrigerant for residential air-conditioners
As for the R410A refrigerant which we have been usually using for air-conditioners, in case of emissions into the atmo-
sphere, we have been adopting the collection of refrigerant etc. in order to restrain the world from global warming.
Based on the 4th basic ecological plan, it is said that the amount of emission of the green house effect gases including the
refrigerants which are being used for air-conditioners shall be reduced 80% by 2050, emissions of any kind of freon gases
which have especially high global warming coefficient must be reduced much more.
Hence, it is required to converted the freon gases we are using for air-conditioners into the refrigerants which have lower
global warming even though they are exhausted into the atmosphere.
On the other hand, the refrigerants for air-conditioners, lower effect of global warming, to secure its performance and high
energy efficiency and safety are required, however, the refrigerants which satisfy all of them have not been announced yet.
For this purpose, we have been studying to make use of the refrigerant like R32 which has short life in the atmosphere, even
though it has low global warming but low combustibility under the practical use for safety.
In 2004, IEC, international electrical safety for air-conditioners had been corrected, the regulation for safety of air-condition-
ers which use the combustible refrigerant have been issued, in 2010, the regulation adopting the degree which is considered
to be damaged slightly because of difficulty of ignition due to its low combustion speed was issued in ANSI/ASHRAE34
regulations.
R32 has been approved as the refrigerant whose combustion speed degree is lower than 10cm/sec, the standardization for
safety use is being proceeded so that R32 can be used more widely.
Although all the air-conditioners which use R32 have been designed with deep consideration in order to guarantee the safe-
ty, some cautions which are mandatory to be kept during its installation and services are shown as follows.
1-2) Chemical characteristics of R32
( i ) Chemical charactaristic
R32 is one of an ingredient which composes R410A, without toxicity, the chemically stable compound which consists
of carbon and fluorine.
Life of R32 after diffusing in the atmosphere is very short, approximately 4.9 years, as a result, although the effect to
global warming can be reduced, there are little combustible due to large ratio of hydrogen.
Chemical formation
Composition
(Mixture ratio weight%)
Boiling point
Pressure at 50 ℃
Performance at 0/50 ℃
COP at Te/Tc/SC/SH=5/50/3/0 ℃
ODP(Ozone Depletion Potential)
GWP(Global Warming Potential)
Combustible charactaristic
Toxicity
( ii ) Pressure charactaristic
As mentioned in table 2, vapor pressure of R32 is almost same as R410A under the identical refrigerant temperature,
and it has 1.6 times of high performance comparision with R22.
Therefore, tool and apparatus which are intended to be used under high pressure condition shall be required same as
R410A when service and installation are implemented.
Table1 Chemical charactaristic
R32
CH F
2 2
Single composition
-51.7 ℃
3.14
160
95
0
675
A2L
No
171
- -
'22 • SRK-T-362
R410A
CH F /CHF CF
2 2 2 3
R32/R125
Single composition
(50/50 weight%)
-51.5 ℃
3.07
141
91
0
2090
A1
No
R22
CHCLF
2
-40.8 ℃
1.94
100
100
0.055
1810
A1
No