In a DX coil evaporator, the refrigerant should leave in what state?

In a DX coil evaporator, the refrigerant should leave in a superheated vapor state. This is because, in a direct expansion (DX) system, the refrigerant absorbs heat as it evaporates in the evaporator coil. As it passes through the coil, the refrigerant transitions from a liquid to a vapor while absorbing heat from the surrounding air.

For optimal performance, once the refrigerant has fully evaporated, it should not still contain any liquid; otherwise, it can cause issues such as flooding the compressor, leading to mechanical damage. By the time the refrigerant exits the coil, it should be completely in vapor form, ideally in a superheated state to ensure all the liquid refrigerant has transformed into vapor. This superheating also ensures that the vapor entering the compressor is at a temperature high enough to improve efficiency and avoid damaging liquid entering the compressor. Therefore, leaving the evaporator in a superheated vapor state is crucial for the effective operation and longevity of the refrigeration system.