To ensure safe and efficient operation of a LiBr absorption chiller, it’s crucial to maintain proper temperature levels in both the chilled water and refrigerant water systems. Here’s a breakdown of the issues and control measures:

1. Excessively Low Chilled Water Outlet Temperature

• Problem: When the chilled water outlet temperature drops too low, the dilute solution's mass fraction rises, leading to the potential for solution pump suction emptying. This causes the concentrated solution mass fraction to increase, creating a risk of solution crystallization.
• Further Effects: A very low evaporator temperature can cause refrigerant water to freeze, impacting system integrity and resulting in a sharp decrease in cooling capacity.
• Solution: Ensure that the chilled water outlet temperature is kept within safe limits to avoid the crystallization of the solution and freezing in the evaporator.

2. Excessively High Refrigerant Water Outlet Temperature

• Problem: When the refrigerant water outlet temperature rises excessively, the liquid level in the evaporator drops, leading to refrigerant pump suction emptying. This reduces the effective refrigerant flow and causes the system's refrigeration output to stabilize or even decline.
• Solution: Control the refrigerant water outlet temperature to stay above 3°C and monitor the refrigerant water level. Avoiding emptying at the pump suction point protects the unit from possible damage and maintains optimal cooling efficiency.

By carefully monitoring and controlling the temperature and water levels in the chiller's evaporator and refrigerant circuit, operators can prevent operational issues like crystallization and freezing, which ultimately protect and extend the life of the LiBr absorption unit.