Which refrigerant is commonly used in modern absorption refrigerators?

Ammonia is commonly used in modern absorption refrigerators due to its effective thermodynamic properties and its suitability for absorption refrigeration systems. In these systems, ammonia serves as the refrigerant that absorbs heat during the evaporation process, making it essential for cooling applications. Its high cooling capacity and efficiency in low-temperature operations contribute significantly to the effectiveness of absorption refrigeration.

The use of ammonia is particularly prevalent in large-scale applications, such as commercial refrigeration and industrial processes, because of its efficiency and relatively low environmental impact compared to synthetic refrigerants. Additionally, ammonia is a natural refrigerant that does not deplete the ozone layer and has a low global warming potential, aligning with modern sustainability goals in refrigerant use.

In contrast, the other refrigerants listed, such as R-12, Freon, and R-134a, are primarily found in compression refrigeration systems or have been phased out in many applications due to environmental concerns related to ozone depletion or greenhouse gas emissions. Therefore, recognizing ammonia's role in absorption refrigerators underscores the evolution of refrigerants in line with both efficiency and environmental regulations.