Several situations of chiller failure

As we all know, with the rapid development of modern industrial technology, in order to improve production efficiency, improve product quality, and reduce production costs, the requirements for temperature control in the production process are getting higher and higher. However, there are more and more failure problems of some chillers, so we have conducted a brief analysis of some failure problems of chillers.



A. What should I do if the temperature difference between the inlet and outlet of the chiller is small?

When the user encounters this situation when using the chiller: that is, the company uses a chiller, the current inlet water temperature is 24°C, and the outlet water temperature is 23°C, and the temperature difference is too small to meet the needs of the user. The main reasons for the small temperature difference between the inlet and outlet water are as follows:


1. The output cooling capacity of the chiller is small, such as the unit itself is faulty or not fully loaded, etc. These can be preliminarily judged by observing parameters such as the operating current of the chiller.


2. It may also be that the heat transfer effect is not good. For example, the heat transfer tube has serious scaling, which affects the heat transfer of the chiller. This can be judged by observing the heat transfer temperature difference between the water temperature and the evaporation temperature.


3. The water flow is too large, which can be judged by observing the pressure difference between the inlet and outlet of the evaporator and the running current of the pump.


4.After eliminating the above problems, you can consider whether the sensor or the thermometer is inaccurate.


B.The chiller fan produces noise


Noise is an annoying sound, and continuous noise can also pollute the surrounding environment. The reasons for the noise generated by the general chiller fan can be described as follows:


As the blades rotate, they rub against the air, or shock. The frequency of noise is composed of multiple frequencies, and these frequencies are related to the speed of the fan. Suggestion: If the axial flow fan has the configuration of moving wing and static wing, the number of blades of the two should be different, so as to avoid greater noise resonance.


Noise is also generated when eddy currents are generated by the blades. During the operation of the fan, a vortex will be generated on the back of the moving wing, which will not only reduce the efficiency of the fan, but also generate noise. In order to reduce this phenomenon, the installation angle of the blade should not be too large, and the bending of the fan blade should be smooth, and it should not change too much suddenly.


Noise occurs due to resonance with the duct housing. The joint between the air duct and the inner surface of the fan casing should be flat to avoid roughness and tearing. In addition, when designing, sometimes the outside of the air duct can be covered with a soundproof material, which can reduce noise.


Furthermore, there are many sources of noise in addition to the stationary noise of the fan itself. Such as: bearings due to insufficient precision, improper assembly or poor maintenance can cause abnormal noise.


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C. Low voltage fault

The suction pressure of the compressor is too low, causing the low pressure protection relay to act. Compressor suction pressure reflects the evaporation pressure, the normal value should be 0.4 ~ 0.6MPa, the protection value is set to 0.2MPa. If the suction pressure is low, the amount of return air will be small, the cooling capacity will be insufficient, and the waste of electric energy will be caused.

The causes of low pressure faults are: insufficient or leaking refrigerant; insufficient refrigerant or water flow; blocked evaporator, poor heat exchange, false alarm caused by electrical failure; low outside temperature.


D. High voltage fault


The compressor discharge pressure is too high, causing the high pressure protection relay to act. The compressor discharge pressure reflects the condensing pressure, the normal value should be 1.4 ~ 1.6MPa, and the protection value is set to 2.0MPa. If the pressure is too high for a long time, it will cause the compressor running current to be too large, which will easily burn the motor and cause damage to the valve plate of the compressor discharge port.


The reasons for the high pressure fault are as follows: the cooling water temperature is too high, and the condensation effect is not good; the cooling water flow is insufficient and cannot reach the rated water flow; the condenser is scaled or blocked; the refrigerant is charged too much; the refrigerant is mixed with air and ammonia Non-condensable gases such as gas; false alarms caused by electrical faults.


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E. Communication failure


The control of each module by the computer controller is realized through the communication line and the main interface board. The main reason for the communication failure is the poor contact or open circuit of the communication line, especially the poor contact caused by the interface being damp and oxidized.


F.compressor overheating failure


The compressor motor winding is embedded with a thermistor, and the resistance is generally 1kΩ. When the winding is overheated, the resistance value will increase rapidly. When it exceeds 141kΩ, the thermal protection module SSM will act to cut off the operation of the unit, and the overheating fault indicator will be on at the same time.


The reasons for compressor overheating failure are as follows: compressor load is too large, overcurrent operation; compressor overcurrent operation caused by electrical fault; overheating protection module is damp or damaged, intermediate relay is damaged, and contacts are bad.


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G.low valve temperature failure


The outlet temperature of the expansion valve reflects the evaporation temperature, which is a factor affecting the heat exchange. Generally, the difference between it and the outlet temperature of the refrigerant water is 5~6℃. When a low valve temperature fault occurs, the compressor will stop, and when the valve temperature rises, it will automatically resume operation with a protection value of -2°C.

The reasons for the low valve temperature failure are as follows: a small amount of refrigerant leakage; the expansion valve is blocked or the opening degree is too small; the refrigerant water flow is insufficient or the evaporator is blocked; false alarms caused by electrical faults.


Contact Information:

Contact:Lingling Chak

Tel:+86 15014759516

Email:morimachinery@163.com

Email:linglingchak@outlook.com

Address:Zhongkai  High-tech Zone,  Huizhou City,Guangdong Province,China


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