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Our refrigerant focus series consists of deep dives into the history, properties, suitable applications and pros and cons of some of today’s common refrigerants. This installment will focus on R-448A.
R-448A was developed between 2010 and 2015, the result of a collaborative effort among Honeywell, the University of Maryland, and Oak Ridge National Laboratory’s Building Technologies Research & Integration Center.
The stated goal of this research was to develop next-gen refrigerants, the performance of which would allow for a 50% reduction in energy consumption of the equipment in which it was used. Specifically, this work sought to synthesize a refrigerant to replace R-22, R-404A, and R-507 in low-to-medium temperature applications, such as supermarket refrigeration.
R-448A is a low-toxicity, non-flammable blended refrigerant, classified by ASHRAE into safety group A1. It's is a 5-part zeotropic blend, made using a combination of hydrofluorocarbon and hydrofluoroolefin constituents at the concentrations outlined below.
The table below shows R-448A’s properties compared to the properties of the refrigerants it is intended to replace.
|
|
R-448A | R-404A | R-22 |
|
Formula |
R-32 (26%) R-125 (26%) R-134a (21%) R-1234ze (7%) R-1234yf (20%) |
R-125 (44%) R-143A (52%) R-134A (4%) |
CHCLF2 |
|
Molecular weight (g/mol) |
86.3 |
97.6 |
86.47 |
|
Boiling Temp ˚F (˚C) |
-43.27 (-45.9) |
-51 (-46.2) |
-41.4 (-40.8) |
|
Critical Temp ˚F (˚C) |
182.6 (83.7) |
161.7 (72) |
205 (96.1) |
|
Critical pressure, PSI (Bar) |
675.9 (46.6) |
541 (37.7) |
723.7 (49.9) |
|
Global Warming Potential |
~1360 |
3922 |
~1810 |
|
Ozone Depletion Percentage |
0 |
0 |
0.05 |
|
ASHRAE Safety Group |
A1 |
A1 |
A1 |
For a performance comparison, we’ve run a theoretical 6” x 70” 8-row copper-aluminum evaporator through our coil selection software, Enterprise. The coil’s airside and tube-side requirements are below and the coil’s rating is below that.
|
Inputs |
|||
|
Airside |
Tube-side |
||
|
Airflow |
4,000 SCFM |
Refrigerant suction temp |
35 ˚F |
|
Target capacity |
140,000 Btu/Hr. |
Degrees superheat |
6 ˚F |
|
Entering air temp (dry bulb) |
85 ˚F |
Liquid temp |
100 ˚F |
|
Leaving air temp (dry blub) |
55 ˚F |
|
|
|
Air pressure |
14.696 PSIA |
|
|
|
Performance Comparison: R-448A vs. R-404A |
||||
|
|
R-448A |
R-404A |
Difference (%) |
Difference (abs.) |
|
Coil capacity |
145,558 Btu/hr. |
140,680 Btu/hr. |
3.3% |
4,878 Btu/hr. |
|
Leaving air temp. |
51.6°F |
52.7°F |
-2.6% |
1.1°F |
|
Refrigerant inlet temperature |
33.7°F |
42.7°F |
-27% |
9°F |
|
Refrigerant pressure drop |
7.694 PSI/coil |
13.419 PSI/coil |
-74% |
5.725 PSI/coil |
|
Refrigerant mass flow |
2,179 lb./hr. |
3,228 lb./hr. |
-48% |
1,049 lb./hr. |
|
Circuit loading |
12,130 Btu/hr. |
11,723 Btu/hr. |
3.3% |
407 Btu/hr. |
|
Performance Comparison: R-448A vs. R-22 |
||||
|
|
R-448A |
R-22 |
Difference (%) |
Difference (abs.) |
|
Coil capacity |
145,558 Btu/hr. |
144,347 Btu/hr. |
0.8% |
1,211 Btu/hr. |
|
Leaving air temp. |
51.6°F |
51.9°F |
0.6% |
0.3°F |
|
Refrigerant inlet temperature |
33.7°F |
40.1°F |
19% |
6.4°F |
|
Refrigerant pressure drop |
7.694 PSI/coil |
6.905 PSI/coil |
-10.2% |
0.789 PSI/coil |
|
Refrigerant mass flow |
2,179 lb./hr. |
2,082 lb./hr. |
-4.4% |
97 lb./hr. |
|
Circuit loading |
12,130 Btu/hr. |
12,029 Btu/hr. |
-0.8% |
101 Btu/hr. |
The chief benefit of R-448A is its lessened environmental impact relative to the refrigerants it was designed to replace. It’s non-ozone depleting and has a global warming potential of 1320, which is 37% less than R-22 and 197% less than R-404.
And, while R-448A’s performance compares similarly to R-22, that refrigerant has been nearly totally phased out. And when compared to the less-regulated R-404A, R-448A resulted in a per-coil capacity increase of just over 3%. R-448A also demonstrated a significantly lower (74%) pressure drop in our hypothetical application.
One minor drawback of R-448A is that, due to it being a zeotropic mixture, it does have a temperature glide of between 5 and 8˚F – a variable that merits attention when designing equipment.
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