R600a and R290 Compared
R600a is isobutane (C₄H₁₀), and R290 is propane (C₃H₈). Both are hydrocarbon refrigerants. R600a has a normal boiling point of approximately −11.6°C; R290 boils at approximately −42.1°C. At 20°C, their saturation pressures are approximately 3.0 bar absolute and 8.4 bar absolute, respectively. R290 also has a higher volumetric refrigeration capacity under comparable conditions. Both have zero ozone depletion potential and very low global warming potential. The main differences lie in their pressure levels and the cooling capacity available per unit volume of refrigerant vapor. Secop application guideline.
| Property | R600a | R290 |
|---|---|---|
| Chemical name | Isobutane | Propane |
| Chemical formula | C₄H₁₀ | C₃H₈ |
| Normal boiling point | −11.6°C | −42.1°C |
| Saturation pressure at 20°C | 3.0 bar absolute | 8.4 bar absolute |
| Volumetric refrigeration capacity* | Lower | Higher |
| Ozone depletion potential (ODP) | 0 | 0 |
| Global warming potential (GWP) | Very low | Very low |
| Flammability | Highly flammable | Highly flammable |
Source: Secop — Application Guideline for R600a and R290.
What the Differences Mean
The pressure difference means R290 operates at higher saturation pressures at the same evaporating or condensing temperature. R600a’s saturation pressure falls below atmospheric pressure at temperatures below its normal boiling point, including temperatures commonly used in freezer evaporators. Volumetric refrigeration capacity describes the cooling effect available per unit volume of vapor entering the compressor. R290’s higher value generally allows a smaller compressor displacement for a given cooling capacity, with comparable operating conditions and compressor efficiencies. The boiling-point difference alone does not determine the lowest temperature an appliance can reach. A higher volumetric capacity is also not a measure of lower electricity consumption. Secop application guideline.
Energy Efficiency
Both R600a and R290 have favorable thermodynamic properties. The same refrigerant can produce different electricity consumption figures because the appliance determines how efficiently cooling is delivered and how often the compressor needs to run. A useful comparison requires the same cooling duty and clearly stated test conditions. Research involving R600a/R290 blends also needs careful interpretation: a 2025 household refrigerator-freezer study tested small additions of R290 to R600a and reported changes in cooling capacity and coefficient of performance. Those results describe the tested mixtures and apparatus; they do not establish an efficiency advantage for pure R290 over pure R600a. A cost comparison should also account for the safety measures required for flammable refrigerants. Both R600a and R290 need suitable protection against ignition, so neither can be assumed cheaper to implement simply because the refrigerant itself costs less. Danfoss hydrocarbon overview; Kazmi et al., 2025.
Typical Applications
R600a is widely used in household refrigerators and freezers, where compressors are designed around its lower pressure and volumetric capacity. R290 is common in commercial refrigeration, including retail display cabinets and food-service equipment. Its higher volumetric capacity supports compact compressors for higher cooling duties. R290 also appears in heat pumps, air-conditioning equipment, and medical cooling applications. These are typical application patterns rather than exclusive categories: the refrigerant designation does not, by itself, identify an appliance as domestic or commercial. The connection between refrigerant properties and application is most useful when considered alongside the required cooling capacity and operating temperature. Secop hydrocarbon refrigerants.
Safety and Environmental Impact
R600a and R290 are highly flammable, so their use requires appropriate measures to control leakage and ignition risks. R600a’s lower operating pressure does not remove its flammability. The permitted refrigerant charge is set by the safety requirements that apply to a particular appliance in its intended market. A limit specified for one appliance cannot automatically be applied to another. Both refrigerants avoid ozone depletion and have a low direct climate impact compared with many conventional fluorinated refrigerants. Their environmental performance over an appliance’s lifetime also depends on electricity consumption. Safe handling and servicing require procedures and equipment suitable for flammable refrigerants. Danfoss hydrocarbon overview.
