Where is refrigerant added in a centrifugal chiller system?

In a centrifugal chiller system, refrigerant is added through a charging valve on the side of the compressor. This is the correct location for refrigerant addition because the compressor plays a crucial role in the refrigeration cycle. By charging refrigerant at this point, it allows for a more accurate and efficient addition of refrigerant into the system, ensuring that the correct levels are maintained for optimal performance.

Adding refrigerant at the compressor side ensures that it enters the system under conditions that facilitate proper mixing and distribution throughout the system components. This is critical because if done incorrectly or at the wrong point in the system, it may lead to improper system operation or inefficiencies.

The other options, while related to different components of the chiller system, do not provide the ideal location for adding refrigerant. For instance, adding refrigerant at the evaporator or expansion valve could disrupt the proper flow and operating pressures needed for effective heat exchange, leading to performance issues.