Reasons and treatment methods for low evaporation pressure and high condensation pressure of screw chillers

Reason for low evaporation pressure of screw chiller:
(1) Insufficient amount of cold water and refrigerant, resulting in low evaporation pressure;
(2) Low cooling load, throttle orifice failure (only causing low evaporation pressure).
(3) The heat transfer tube of the evaporator deteriorates due to pollution such as scale (only causing the evaporation pressure to be too low).
Solution:
(1) Check the set temperature of the cold water circuit and automatic start stop device to ensure that the cold water volume reaches the rated water volume;
(2) Check if the expansion throttle pipe is unobstructed.
(3) Clean the heat transfer tube.
(4) Replenish the refrigerant to the required amount.
Reasons for high condensation pressure in screw chillers:
(1) Insufficient cold water, high water temperature, and large refrigeration capacity increase the load on the condenser;
(2) The capacity of the cooling tower is reduced and there is air present;
(3) The condenser tubes have deteriorated heat transfer due to contamination such as scale.
Handling method:
(1) Clean the pipes and check the cooling water circuit, adjust to the rated flow rate.
(2) Check the expansion throttle pipe, etc., to make the cold water temperature close to the rated temperature as soon as possible.
(3) Perform air extraction operation to remove air. If the extraction device needs to operate frequently, it is necessary to identify the location of air leakage and eliminate it.