What effect does air in the refrigeration system have on head pressure?

Air in the refrigeration system significantly impacts head pressure by leading to an increase. When air enters the system, it often mixes with the refrigerant, creating a non-condensable gas mixture. This mixture can occupy space within the condenser, which affects the thermodynamic properties of the refrigerant.

As the non-condensable gases (air) accumulate in the condenser, the pressure required to condense the refrigerant increases. This is because the condenser must now work harder to reject heat to the ambient environment. Consequently, the compressor will have to operate at a higher pressure to maintain system performance, thereby raising the head pressure.

In a properly functioning system, the head pressure is determined primarily by the temperature at which the refrigerant can condense, which is disrupted by the presence of non-condensable gases like air. Therefore, allowing air to infiltrate the system can lead to inefficiencies and increased operational difficulties, necessitating that the system is purged and maintained to prevent air contamination.