Difference Between Chillers with Flooded Evaporators and Chillers with DX (Direct Expansion) Evaporators

Chillers that use flooded or DX evaporators differ significantly in how refrigerant flows and how heat is transferred within the system.

In a chiller with a flooded evaporator, the water-carrying tubes are submerged in a large volume of liquid refrigerant. Only vaporized refrigerant is drawn into the compressor. This design results in very low superheat, which improves heat transfer efficiency and allows the water to be cooled more quickly.

In contrast, a chiller with a DX (Direct Expansion) evaporator injects refrigerant directly into the evaporator tubes. The refrigerant absorbs heat from the water and evaporates inside the tubes. To prevent liquid refrigerant from reaching the compressor, a higher superheat must be maintained, which can reduce overall system efficiency.

Overall, chillers with flooded evaporators are typically used in large-capacity and industrial applications due to their higher efficiency, while chillers with DX evaporators are more commonly found in smaller systems such as mini chillers and ducted split units.