First, what should I do if the temperature difference between the water in and out of the chiller is small?
When the user encounters this situation when using a chiller: that is, the company uses a chiller, and the inlet temperature is 24 ° C and the outlet temperature is 23 ° C. The temperature difference is too small to meet the user's needs. For the reason that the temperature difference between the inlet and outlet water is too small, there are mainly the following situations:
1. The output cold capacity of the chiller is small, such as the unit itself is faulty, or is not fully loaded, etc. These can be preliminary judged by observing the chiller operating current and other parameters.
2. It may also be that the heat transfer effect is not good. For example, the scaling of the heat transfer tube is serious, which affects the heat exchange 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. This can be judged by observing the pressure difference between the inlet and outlet water 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.
Noise from chiller fan
Noise is an annoying sound. Continuous noise can also pollute the surrounding environment. The causes of noise generated by general chiller fans can be described as follows:
When the blade rotates, it will cause friction with the air or impact. The frequency of the noise is a combination of multiple frequencies, all of which are related to the speed of the fan. Suggestion: If the axial flow fan is equipped with moving and static wings, the number of blades of the two should be different, so as not to cause greater noise resonance.
Noise is also generated when the blade generates eddy currents. During the operation of the fan, a vortex will be generated on the back of the moving wing. This vortex 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 must not be too large, and the curvature of the fan blade must be smooth, and the sudden change should not be too large.
Resonates with the duct housing and generates noise. The inner seam of the air duct and the fan casing should be flat to avoid rough and uneven, causing tearing sound. In addition, when designing, the outer surface of the duct can be covered with sound-proof materials to reduce noise.
In addition to the fixed noise of the fan itself, there are many noise sources. Such as: due to insufficient precision of the bearing, improper assembly or poor maintenance can cause abnormal noise.
The computer controller controls each module through the communication line and the main interface board. The main cause of the communication failure is the poor contact or disconnection of the communication line, especially the interface is affected by moisture and oxidation, and the unit electronic board or the general interface Board failure, improper selection of address dial switch, power failure can cause communication failure.
Fourth, low voltage failure
The compressor suction pressure is too low, causing the low-voltage protection relay to operate. 2MPa。 The 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 is small and the cooling capacity is insufficient, resulting in a waste of electrical energy. Poor heat dissipation for the compressor motor cooled by the return air will easily damage the motor.
The causes of low-pressure faults are: insufficient refrigerant or leakage; insufficient refrigerant water flow; blockage of the evaporator and poor heat exchange; false alarms caused by electrical faults; and low outside air temperatures.
Five, high voltage failure
The compressor discharge pressure is too high, causing the high-pressure protection relay to operate. 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 period of time, it will cause the compressor to run too much current, burn the motor easily, and damage the valve flap of the compressor exhaust port.
The causes of the high-pressure failure are as follows: The cooling water temperature is too high and the condensation effect is poor; the cooling water flow is insufficient to reach the rated water flow; the condenser is scaled or blocked; the refrigerant is overcharged; the refrigerant is mixed with air and nitrogen Wait for non-condensing gas; false alarm caused by electrical fault.
Compressor overheating failure
The thermistor is embedded in the compressor motor winding, 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 be activated to cut off the unit operation, and the overheat fault indicator will be on.
The reasons for the overheating of the compressor are as follows: The compressor is overloaded and runs in overcurrent; the compressor is running in overcurrent caused by an electrical fault; the overheating protection module is wet or damaged, the intermediate relay is damaged, and the contacts are bad.
Seven, low valve temperature failure
The expansion valve outlet temperature reflects the evaporation temperature, which is a factor that affects heat transfer. Generally, the temperature difference between the outlet temperature of the expansion valve and the refrigerant water is 5-6 ° C. When a low valve temperature fault occurs, the compressor will stop. 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 leaks; 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.