What types of refrigerants are typically used in low-pressure refrigeration systems?

In low-pressure refrigeration systems, ammonia and carbon dioxide are indeed the types of refrigerants commonly used. Ammonia (NH3) is favored for its high efficiency and effectiveness as a refrigerant in industrial applications, particularly in large-scale refrigeration systems. It has excellent thermodynamic properties, making it suitable for low-temperature operations. Additionally, ammonia has a low global warming potential and is relatively cost-effective.

Carbon dioxide (CO2), on the other hand, is gaining popularity as a refrigerant due to its low environmental impact and efficiency in certain applications. Under low pressure, carbon dioxide operates effectively in refrigeration cycles, particularly in systems designed for specific temperature ranges.

Other options, like Freon and ether, and hydrocarbons such as propane and butane, are typically associated more with mid to high-pressure systems. R-134a and isobutane are often used in refrigerants for various applications, but they generally do not serve as the primary choice for low-pressure systems. This distinction makes ammonia and carbon dioxide the preferred refrigerants in low-pressure setups.