Why is refrigerant vapor re-introduced to the chiller before refrigerant liquid after servicing?

Reintroducing refrigerant vapor to the chiller before adding refrigerant liquid is vital for preventing potential freezing conditions in the heat exchanger tube bundle. When the refrigerant is in vapor form, it can mix and circulate in the system without causing any drastic temperature changes that could lead to ice formation on the heat exchanger surfaces.

If refrigerant liquid were introduced directly, especially in significant amounts, it could cause a rapid drop in temperature in localized areas, risking the freezing of water or other fluids within the heat exchanger. This could not only impair the functioning of the chiller but might also lead to physical damage due to ice expansion.

Overall, gradually introducing vapor helps maintain a stable and efficient operational temperature throughout the chiller system, ensuring effective heat transfer and reducing the risk of service-related damages.