A complete analysis of common problems of air-cooled screw chillers

As a highly efficient refrigeration equipment, air-cooled screw chillers are widely used in many fields such as commerce and industry, providing a reliable low-temperature environment for production and life. However, in the long-term operation process, this type of equipment will inevitably have some problems, affecting its performance and normal use. Understanding common problems and their causes is crucial for timely maintenance and ensuring stable operation of equipment.

Insufficient cooling capacity

Insufficient cooling capacity is one of the more common problems of air-cooled screw chillers. This may be caused by a variety of factors. First of all, refrigerant leakage is a key reason. Refrigerant circulates in the system to achieve heat exchange. If there is a leak, the circulation volume is reduced and the cooling capacity naturally decreases. Common leaking sites include pipe welds, valve connections, etc. In addition, scaling of the evaporator or condenser will also affect the cooling capacity. Evaporator scaling hinders the transfer of heat from the chilled water to the refrigerant, and condenser scaling makes it difficult for the refrigerant's heat to dissipate into the air. Both will reduce the heat exchange efficiency of the unit, leading to insufficient cooling capacity.

Compressor failure

The compressor is the core component of the chiller, and its failure has a huge impact on the equipment. Compressor failure may manifest as failure to start, abnormal noise or vibration, etc. Electrical failure is a common cause of compressor failure, such as motor winding short circuit, open circuit, contactor failure, etc. Mechanical failure should not be ignored. For example, bearing wear and piston ring damage inside the compressor will cause abnormal noise and vibration when the compressor is running. In severe cases, the refrigerant cannot be compressed normally, causing the unit to lose its cooling capacity.

Oil temperature is too high

Normal oil temperature is an important condition to ensure the good operation of the compressor. When the oil temperature is too high, it will affect the lubrication effect of the compressor and increase the risk of component wear. There are many factors that lead to excessive oil temperature, such as cooling system failure. Air-cooled units rely on air to cool the lubricating oil. If the cooling fan fails or there is too much dust on the heat sink, the cooling effect will be reduced and the oil temperature will rise. In addition, if the compressor runs at high load for a long time, too much heat will be generated and cannot be dissipated in time, which will also cause the oil temperature to be too high.

Frequent start and stop of the unit

Frequent start and stop of the unit will not only affect the life of the equipment, but also may lead to energy waste. Pressure controller failure is one of the common factors that cause frequent start and stop. The pressure controller is used to monitor the system pressure and control the start and stop of the unit when the pressure is abnormal. If the pressure controller fails and incorrectly senses the pressure signal, it may cause unnecessary frequent start and stop of the unit. In addition, the presence of non-condensable gases such as air in the system will also cause abnormal pressure fluctuations, causing frequent start and stop of the unit.

Fan failure

The fan of the air-cooled screw chiller is responsible for dissipating heat for the condenser. Fan failure will seriously affect the cooling effect of the unit. Fan failure may manifest as the fan not turning or abnormal speed. Motor burnout, fan blade damage or deformation are common causes. The fan motor may burn out due to overload, insulation aging and other problems after long-term operation. During operation, the fan blades may be damaged and deformed by foreign objects, affecting the normal operation and cooling effect of the fan.

Solution

For the above common problems, corresponding solutions need to be taken. For the problem of insufficient cooling capacity, leaks should be checked and refrigerant should be added in time, and the evaporator and condenser should be cleaned regularly to remove dirt. When the compressor fails, it is necessary to accurately determine whether it is an electrical or mechanical problem, and repair or replace the corresponding parts respectively. When the oil temperature is too high, check the cooling system, clean the dust on the heat sink, repair or replace the faulty fan, and adjust the compressor operating load if necessary. For the problem of frequent start and stop of the unit, calibrate or replace the pressure controller, and eliminate the non-condensable gas in the system. If the fan fails, the damaged motor or blades need to be replaced.

Common problems with air-cooled screw chillers include cooling capacity, compressors, oil temperature, start and stop, and fans. By understanding and analyzing these problems, operators and maintenance personnel can promptly discover and solve them, ensure stable and efficient operation of the unit, extend the service life of the equipment, and provide continuous and reliable refrigeration for production and life. In actual applications, daily inspections and maintenance of equipment should also be strengthened to prevent problems, reduce equipment failure rates, and improve operating efficiency.