Our Refrigerant Focus series delves into the history, properties, suitable applications, and pros and cons of some of today’s popular or otherwise noteworthy refrigerants. This installment will focus on R-290 (propane).
Check out some of our refrigerant focus posts below.
R-290, commonly known as propane, is used for low-to-medium temperature refrigeration applications like freezers and refrigerated display cases, and has a lengthy history as a refrigerant. In fact, along with natural refrigerants like ammonia (R-717) and isobutane (R-600a), propane played an instrumental role in our early understanding of the compression and expansion-based cooling process that laid the foundation for modern refrigeration equipment.
The first commercially available propane refrigeration equipment was developed in the 1930s, coinciding with the emergence of synthetic refrigerants like R-12. These new refrigerants - and the dozens of subsequent formulations that would follow - became the standard, and efforts to find additional uses for R-290 fizzled out. It remained a popular option for small-scale refrigeration applications (vending machines, refrigerators, etc.) and industrial processes, but few others. However, along with natural refrigerants like CO2, propane refrigeration is experiencing something of a renaissance, as manufacturers continue the search for high-performance refrigerants that comply with today's regulations. Today, R-290 is used as a low-global warming potential (GWP) replacement for refrigerants R-22, R-404, & R-134a for certain applications.
R-290 is a single-component hydrocarbon substance. It's a byproduct created during the refinement of natural gas and petroleum. The most notable of propane's properties is its flammability More properties for R-290 can be found in the table below.
R-290 Properties |
|
Formula |
C3H8 |
Molecular weight (g/mol) |
44.1 |
Boiling temperature °F (°C) |
-43.8 (-42.1) |
Critical temperature °F (°C) |
206.1 (96.7) |
Critical pressure, PSI, (Bar) |
616.5 (42.5) |
Global Warming Potential |
3 |
Ozone Depletion Potential |
0 |
ASHRAE Safety Group |
A3 |
For a performance comparison, we’ve run a theoretical 36” x 70” 2-row condenser through our coil selection software, Enterprise. The coil’s airside and tube-side requirements are below and the coil’s rating is below that.
The design conditions are shown below along with the performance rating for that coil using R-290, R-22, R-404A and R-134a.
Inputs | |||
Airside |
Tube-side |
||
Air flow |
4,000 SCFM |
Condensing temp. |
135°F |
Target capacity |
165,000 Btu./hr. |
Hot gas temp. |
180°F |
Entering air temp. |
90°F |
Subcooling degrees | 5°F |
Leaving air temp. |
55°F/45°F (WB) |
||
Air pressure |
14.696 PSIG |
Performance Comparison: R-22 vs. R-290 |
||||
R-22 |
R-290 |
Difference (%) |
Difference (abs.) |
|
Coil capacity |
186,478 Btu/hr. |
180,537 |
-3.3% |
5,941 Btu/hr. |
Leaving air temp. |
107°F |
106.4°F |
-0.5% |
0.6°F |
Refrigerant pressure drop |
6.59 PSI/coil |
4.428 PSI/coil |
-49% |
2.162 PSI/coil |
Refrigerant mass flow |
2,481 lb./hr. |
1,243 lb./hr. |
-49.9% |
1,238 lb./hr. |
Performance Comparison: R-134a vs. R-290 |
||||
R-134A |
R-290 |
Difference (%) |
Difference (abs.) |
|
Coil capacity |
188,375 Btu/hr. |
180,537 Btu/hr. |
-4.1% |
7,838 Btu/hr. |
Leaving air temp. (WB) |
107.1°F |
106.4°F |
-0.7% |
0.7°F |
Refrigerant pressure drop |
6.922 PSI/coil |
4.428 PSI/coil |
-36% |
2.494 PSI/coil |
Refrigerant mass flow |
2,465 lb./hr. |
1,243 lb./hr. |
-49.6% |
978 lb./hr. |
Performance Comparison: R-404A vs. R-290 |
||||
R-404A |
R-290 |
Difference (%) |
Difference (abs.) |
|
Coil capacity |
185,669 Btu/hr. |
180,537 Btu/hr. |
-2.8% |
5,132 Btu/hr. |
Leaving air temp. (WB) |
106.9°F |
106.4°F |
-0.5% |
0.5°F |
Refrigerant pressure drop |
6.156 PSI/coil |
4.428 PSI/coil |
-28% |
1.728 PSI/coil |
Refrigerant mass flow |
3,169 lb./hr. |
1,243 lb./hr. |
-61% |
1,926 lb./hr. |
Note: The same circuiting was used for all three coils.
The main benefits of R-290 are:
The main drawback of R-290 is:
If you're designing a system and can't decide which refrigerant is the best option, drop us a line. We have multiple refrigerant experts on staff that can help you make the right choice to get the most out of your heat transfer equipment.
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