On a centrifugal chiller, the purge unit suction line comes from which part?

The correct answer is that the purge unit suction line comes from the top of the condenser. In a centrifugal chiller system, the purge unit plays a critical role in removing non-condensable gases and ensuring that the refrigerant system operates efficiently.

The top of the condenser is where vaporized refrigerant exits after being cooled and condensed. Non-condensable gases, such as air and moisture that may have leaked into the system, tend to accumulate at the top of the condenser. By drawing from this point, the purge unit can effectively remove these undesired gases, which could lead to reduced chiller efficiency if allowed to accumulate.

Suction lines connected to the bottom of the evaporator or the bottom of the condenser would not be effective for purging non-condensables. This is because these locations typically deal with liquid refrigerant or condensed vapor, which do not contain the trapped gases that need to be purged. The side of the compressor is also not the correct answer as it refers to the mechanical aspect of the chiller and does not serve the purpose of gas removal.

Thus, the configuration of the purge unit that draws from the top of the condenser is essential for maintaining the efficiency and reliability of a centrifugal chiller.