What is the purpose of a surge drum in a flooded refrigeration system?

In a flooded refrigeration system, the primary purpose of a surge drum is to separate vapor from liquid refrigerant. This separation is crucial for ensuring that only high-pressure, saturated liquid refrigerant is sent to the evaporator, which is directly responsible for cooling the space or process. By using a surge drum, the system can maintain an appropriate level of liquid refrigerant to balance the varying loads and operational conditions without risking the introduction of vapor into the evaporator, which could lead to inefficiencies or damage.

The surge drum acts as a reservoir where liquid refrigerant can settle, allowing vapor to rise and exit from the top of the drum. This not only ensures better efficiency in the refrigeration cycle but also allows the system to recover from changes in refrigerant load without fluctuations that could disrupt cooling performance.