R404A is a refrigerant commonly used in cold rooms and freezers, designed for large-scale users such as supermarkets and storage centers. In this article, we will explore the pressures and operation of a cold room that works with R404A refrigerant, as well as the key components and environmental considerations associated with this refrigerant.
Pressures and Operation
Low Pressure
The low pressure present in freezing equipment for an evaporator temperature of -20 degrees Celsius is about -4 degrees Fahrenheit. The absolute pressure is 45.276 PSI, resulting in a gauge pressure value of 30.376 PSI.
High Pressure
The high pressure is determined by using the ambient temperature increased by 15 degrees Celsius. For example, at an ambient temperature of 35 degrees Celsius, the absolute pressure is 337.365 PSI, resulting in a gauge pressure value of 322.665 PSI.
Key Components
- Evaporator
- Solenoid Valve
- Thermostatic Valve or Electronic Controller
- Oil Separator
- Condenser and Condenser Fan Controller
- Evaporator 2
- Electronic Expansion Valve
- Electronic Controller 2
- Chain Decentral Compressor Controller
- Double Pressure Switch
Environmental Considerations
R404A is a refrigerant generated with a mixture of R134a, R125, and R143a gases. It must be charged in the liquid phase. While R404A does not destroy the ozone layer, it has a high global warming potential (GWP) of 3920, causing environmental restrictions due to its GWP being greater than 2500.
Refrigerant Charging and Service Procedures
When working with R404A refrigerant, it’s essential to follow proper refrigerant charging and service procedures. This includes understanding the refrigerant blend, charging in the liquid phase, and adhering to environmental regulations.
Adding Refrigerant
If additional refrigerant needs to be added to the system, it’s crucial to calculate the required amount based on factors such as line set lengths. For example, if the line set length exceeds the maximum recommended length, the technician must calculate the additional refrigerant needed based on the specifications provided.
Environmental Alternatives
Due to the environmental restrictions associated with R404A, there are alternative refrigerants available, such as R407A, R452A, R449A, and R407F. These alternatives offer lower GWPs and can be considered as environmentally friendly options.
Conclusion
Understanding the pressures, operation, and environmental considerations of R404A refrigeration is crucial for HVAC technicians working with cold rooms and freezers. By adhering to proper charging procedures and considering environmental alternatives, technicians can ensure efficient and environmentally responsible refrigeration practices.
