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R290 vs R134a

Comparing refrigerants R290 vs R134a allows us to understand the differences and particularities of these two gases. In the following summary prepared by MundoChiller, we highlight the key characteristics of these substances.

R290 vs R134a Characteristics:

Let’s begin by noting that both R290 and R134a are pure gases. They can be recharged in both liquid and gaseous phases since they are not mixtures of gases.

R290 (propane) is a hydrocarbon used as a refrigerant, primarily in domestic refrigerators, small commercial refrigeration units, low-power machines, air conditioners, and heat pumps.

In contrast, R134a is used in equipment of any capacity, such as domestic refrigerators, commercial systems, chillers for air conditioning in buildings, chillers for cooling machinery, and automotive air conditioning systems.

The main advantage of R290 is its low environmental impact and excellent thermodynamic properties, leading to its increased usage.

  • R290 does not harm the ozone layer and has a Global Warming Potential (GWP) of 3.
  • R134a does not harm the ozone layer but has a GWP of 1430. Over time, this has resulted in stricter environmental restrictions.

Safety Classification:

  • R290: Classified as A3 (non-toxic but highly flammable).
  • R134a: Classified as non-toxic and non-flammable.

While R290 is flammable, its use in low-capacity refrigeration systems reduces risks due to the notably low quantity of refrigerant required.

Lubrication:

  • R290, like other hydrocarbon refrigerants, has good miscibility with most lubricants. However, it is recommended to use oils with higher viscosity grades.
  • R134a is compatible with POE oil in conventional refrigeration systems and PAG oil in automotive air conditioning systems.

Capillary Tube Sizes: The capillary sizes for R290 and R134a differ for the same cooling capacity.

Energy Efficiency: R290 has demonstrated reduced energy consumption in refrigeration systems compared to R134a.

Compatibility: R290 and R134a are not interchangeable in existing systems unless authorized by the manufacturer. Replacing R290 with R134a may result in an unstable system and long-term compressor damage.

Pressure-Temperature Tables:

The pressure values in the following tables are gauge pressures (psig), referenced to atmospheric pressure (14.7 psi).

R290 Pressure-Temperature Table (Gauge Pressure):

Temperature (°C)Temperature (°F)Pressure (psig)
-24-11.231
-22-7.633.36
-20-4.035.86
-18-0.438.66
-163.241.60
-146.844.39
-1210.447.48
-1014.050.71
-817.654.24
-621.257.77
-424.861.59
-228.465.56
032.069.68
235.674.08
439.278.64
642.883.34
846.488.34
1050.093.49
1253.698.93
1457.2104.66
1660.8110.54
1864.4116.57
2068.0122.89
2271.6129.50
2475.2136.41
2678.8143.47
2882.4150.96
3086.0158.61
3289.6166.55
3493.2174.78
3696.8183.31
38100.4192.13
40104.0201.24
42107.6210.65
44111.2220.50
46114.8230.64
48118.4241.08
50122.0251.81
52125.6262.98

R134a Pressure-Temperature Table (Absolute Pressure):

Temperature (°C)Temperature (°F)Pressure (psi)
-30-22.012.34
-25-13.015.58
-20-4.019.40
-155.023.96
-1014.029.40
-523.035.57
032.042.92
541.051.30
1050.060.85
1559.071.73
2068.083.93
2577.097.75
3086.0113.19
3595.0130.53
40104.0149.64
45113.0170.81
50122.0194.04

For example, for a refrigeration system operating at -10°C, the table gives an absolute pressure of 29.4 psi. To calculate the gauge pressure:

Gauge Pressure = Absolute Pressure – Atmospheric Pressure

If the atmospheric pressure is 14.7 psi:

Gauge Pressure = 29.4 psi – 14.7 psi = 14.7 psi

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