Thermodynamic Properties (R11)

The key thermodynamic properties of R11 refrigerant include its composition, application, performance, and lubricant compatibility. R11 is composed of 100% trichlorofluoromethane (CCl3F) and is commonly used in large, low-pressure centrifugal chillers. It was the industry standard choice until the 1990s and is compatible with mineral oil lubricants.

The typical operating pressure range for R11 refrigerant in centrifugal chillers is around 30-60 psia (pounds per square inch absolute) on the low side and 80-120 psia on the high side. However, the exact operating pressure range may vary depending on the specific chiller design and application.

The density of R11 refrigerant changes significantly with temperature. As shown in the table, the density of liquid R11 increases as the temperature decreases, while the density of vapor R11 decreases as the temperature increases. For example, at 40°F (4°C), the density of liquid R11 is around 95 lb/ft³, while at 80°F (27°C), it is around 85 lb/ft³. Understanding these density changes is crucial for proper chiller design and operation.

R11’s thermodynamic properties have significant implications on chiller performance. For instance, its high latent heat of vaporization and low pressure ratio make it suitable for large, low-pressure centrifugal chillers. However, its relatively low critical temperature and pressure limit its application in high-temperature and high-pressure systems. Additionally, R11’s thermodynamic properties affect the chiller’s coefficient of performance (COP), which is a measure of its efficiency.

The lubricant compatibility of R11 refrigerant is critical for chiller maintenance. Since R11 is compatible with mineral oil lubricants, it is essential to ensure that the correct type and amount of lubricant are used in the chiller. Incompatible lubricants can lead to premature wear, corrosion, and equipment failure, resulting in increased maintenance costs and downtime. Regular lubricant analysis and maintenance are necessary to ensure the longevity and reliability of R11-based chillers.

R11 refrigerant is an ozone-depleting substance (ODS) and has a high global warming potential (GWP). Its production and consumption are regulated by the Montreal Protocol, and its use is being phased out in many countries. As a result, it is essential to consider the environmental implications of R11 refrigerant when designing and operating chillers, and to explore alternative refrigerants with lower environmental impact.

Some common alternatives to R11 refrigerant in centrifugal chillers include R123, R134a, and R513A. These refrigerants have similar thermodynamic properties to R11 but are more environmentally friendly. R123, for example, has a lower GWP and is widely used in low-pressure centrifugal chillers. R134a is another popular alternative, but it requires modifications to the chiller design and operation due to its higher pressure ratio. R513A is a newer refrigerant that offers a balance between performance and environmental sustainability.

R11’s thermodynamic properties have significant implications on chiller performance. For instance, its high latent heat of vaporization and low pressure ratio make it suitable for large, low-pressure centrifugal chillers. However, its relatively low critical temperature and pressure limit its application in high-temperature and high-pressure systems. Additionally, R11’s thermodynamic properties affect the chiller’s coefficient of performance (COP), which is a measure of its efficiency.