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When it comes to heat exchangers, there’s a host of decisions that are impacted by application-specific factors. One such choice is the heat exchanger’s working fluid. There are dozens if not hundreds of working fluids to choose from, each with its own properties and applications with which those properties are compatible. For this article, we thought it’d be useful to create a list of some common working fluids grouped by the temperature classification in which they’re typically grouped.
Working fluids are often grouped into one of four categories: ultra-low temperature (ULT), low-temperature, medium-temperature, and high-temperature. The list below shows some working fluids that fit into each group along with a bit of background on the specifics of those classifications as well some examples of applications for which they’re commonly used.
Note: some of the refrigerants included in this article have either been phased out or are in the process of being phased out, which are indicated with **.
When referring to working fluids, “ultra-low temperature” typically describes applications with evaporator temperatures ranging from roughly -50F to -150F. ULT usually refers to fluids used in very low-temperature applications like cryogenic storage, pharmaceutical processes, some environmental chambers, and others. Some examples of such working fluids include:
|
|
R-728 (Liquid nitrogen) |
R-744* (CO2) |
R-717 (ammonia) |
|
Formula |
N₂ |
CO₂ |
NH₃ |
|
Molecular weight (g/mol.) |
28.013 |
44.01 |
17.03 |
|
Boiling temp. °F (°C) |
-320.4 (-195.8) |
-109 (78.5) |
-27.9 (-33.3) |
|
Critical temp °F (°C) |
-232.5 (-146.9) |
87.9 (31.1) |
270.1 (132.3) |
|
Critical pressure, PSI (Bar) |
492.5 (33.9) |
1073 (72.1) |
1643.7 (113.3) |
|
Global Warming Potential |
0 |
1 |
0 |
|
Ozone Depletion Percentage |
0 |
0 |
0 |
|
ASHRAE Safety group |
A1 |
A1 |
B2L |
* - can be used for medium and some high-temp applications as well.
Low temperature typically refers to working fluids with evaporator temperatures between -20F and 20F. The separation between low and medium temp working fluids is somewhat ambiguous, as some low-temp refrigerants can be used for medium-temp applications as well.
Additionally, there aren’t many refrigerants whose suitable applications exclusively involve subzero evaporator temperatures. R-502 and R-507A are two such examples, but regulation now prohibits the usage of both due to their global warming potentials (GWP) of 4790 and 3990, respectively.
The term “medium temperature” is most often used to describe the range of operating temperatures found in applications like commercial refrigeration (evaporator temperatures of roughly 20F – 40F). A list of some common medium temp refrigerants and their properties is below.
|
|
R-454A |
R-454C |
R-448A** |
R-455A |
R-449A** |
R-471a |
R-134a** |
R-513A |
R-452A |
R-290 |
|
Formula |
R-32 (35%) R-1234yf (65%) |
R-32 (21.5%) R-1234yf (78.5%) |
R-32 (26%) R-125 (26%) R-134a (21%) R-1234ze (7%) R-1234yf (20%)
|
R-1234yf (75.5%) R-32 (21.5%) R-744 (3%) |
R-32 (24.3%) R-125 (24.7%) R-134a (25.3%) R-1234yf (25.7%) |
R-1234zeE (78.7%) R-1336MZZe (17%) R-227ea (4.3%) |
CH₂FCF₃ |
R-1234yf (56%) R-134a (44%) |
R-32 (11%) R-125 (59%) R-1234yf (30%) |
C₃H₈ |
|
Molecular weight (g/mol.) |
80.5 |
90.8 |
86.3 |
87.5 |
87.21 |
122.1 |
102 |
108.4 |
103.5 |
44.1 |
|
Boiling temp. °F (°C) |
-54.1 (-47.8) |
-50 (-45.6) |
-43.27 (-45.9) |
-61.6 (-52) |
-50.8 (-46) |
1.6 (-16.9) |
-15 (-26.1) |
-20.4 (-29.1) |
-52.6 (-47) |
-43.8 (-42.1) |
|
Critical temp °F (°C) |
179.1 (81.7) |
186.2 (85.7) |
182.6 (83.7) |
186.1 (85.6) |
179.8 (82.1) |
234 (112.2) |
213.9 (101.1) |
173.7 (96.5) |
166.8 (74.9) |
206.1 (96.7) |
|
Critical pressure, PSI (Bar) |
671 (46.2) |
626.4 (43.2) |
675.9 (46.6) |
675.9 (46.6) |
652.6 (45) |
511.4 (32.3) |
588.8 (40.6) |
546.2 (37.7) |
580.4 (40) |
616.5 (42.5) |
|
Global Warming Potential |
239 |
148 |
~1360 |
146 |
1282 |
<150 |
1430 |
573 |
1945 |
3 |
|
Ozone Depletion Percentage |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
ASHRAE Safety group |
A2L |
A2L |
A1 |
A2L |
A1 |
A1 |
A1 |
A1 |
A1 |
A3 |
This group of working fluids consists of substances used in applications with evaporator temperatures of 40F and above – including many common commercial HVAC applications. A list of some common high temp refrigerants and their properties is below.
|
|
R-410A** |
R-454B |
R-22** |
R-32 |
|
Formula |
R-32 (50%) R-125 (50%) |
R-32 (68.9%) R-1234yf (31.1%) |
CHClF₂ |
CH₂F₂ |
|
Molecular weight (g/mol.) |
72.6 |
62.6 |
86.5 |
52 |
|
Boiling temp. °F (°C) |
-60.9 (-51.6) |
-58.9 (-50.5) |
-41 (-40.5) |
-62 (-52) |
|
Critical temp °F (°C) |
160.4 (71.3) |
172.6 (78.1) |
205.1 (96.2) |
172.6 (78.1) |
|
Critical pressure, PSI (Bar) |
711.1 (49) |
673.9 (46.4) |
723.7 (49.9) |
|
|
Global Warming Potential |
1920 |
466 |
1810 |
675 |
|
Ozone Depletion Percentage |
0 |
0 |
0.055 |
0 |
|
ASHRAE Safety group |
A1 |
A2L |
A1 |
A2L |
If you're looking for some guidance on refrigerant selection, give one of our experts a call today. With performance modeling in Enterprise, our coil selection software, and our engineers' experience in low, medium, and high temp applications, we can work with you to make sure you select the working fluid that fits best with your specific application.
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