What are the three liquid feed types?

The three liquid feed types are indeed dry expansion (DX), overfeed (or recirculated), and flooded (or gravity), all of which are critical in understanding refrigeration and HVAC systems.

Dry expansion refers to a system where the refrigerant is allowed to vaporize fully in the evaporator, which helps maintain efficiency and precise temperature control. This approach is usually suitable for conditions where complete vaporization can be achieved effectively, ensuring optimal performance of the system.

Overfeed or recirculated systems, on the other hand, involve continuously circulating refrigerant through a metering device back into the evaporator. This method is efficient in large refrigeration systems or when dealing with fluctuating loads, as it helps maintain consistent temperature and maximizes cooling capacity.

Flooded or gravity systems operate with a continuous flow of liquid refrigerant in the evaporator, which ensures that the entire heat exchanging surface is utilized. This type of system is particularly efficient in achieving high heat transfer rates because it maintains a proper liquid level, allowing for effective absorption of heat.

Since each of these liquid feed types plays a distinct role in various applications, recognizing all three as part of a comprehensive understanding of refrigeration technology is essential for effective system design and operation.