What type of refrigerant system uses a surge drum to supply refrigerant?

A flooded system is characterized by its use of a surge drum to effectively manage refrigerant flow. In this setup, the surge drum serves as a storage vessel where refrigerant is maintained in a liquid state. This allows the system to ensure that there is a consistent supply of liquid refrigerant available for the evaporator.

In a flooded system, liquid refrigerant fills the evaporator, enhancing the heat exchange efficiency by increasing the surface area in contact with the evaporator coils. This design is particularly beneficial in large refrigeration applications, as it can maintain a more stable and efficient cooling effect over varying load conditions.

Other systems, like a direct expansion (DX) system, do not utilize a surge drum and instead have refrigerant flowing directly into the evaporator, where it expands and absorbs heat. Similarly, recirculated systems and low-pressure systems have different configurations and operational principles that do not necessitate the use of a surge drum to manage refrigerant supply. Thus, the flooded system's design and function directly involve the surge drum, making it the correct answer.