Cold storage refrigeration system fault analysis and solution.

Exhaust pressure is too high
Fault hazard:
If the exhaust gas temperature is too high, the consumption of the compressor lubricating oil is increased, the oil is thinned, and the lubrication is affected;
When the exhaust gas temperature is close to the flash point of the compressor oil, some of the lubricating oil is carbonized and accumulated in the suction and exhaust valve ports, which affects the sealing performance of the valve.
cause of the issue:
1. The cooling water (or air) has a small flow rate and a high temperature;
2. There is air in the system to increase the condensing pressure;
3. The refrigerant charge is too much, and the liquid occupies an effective condensation area;
4. The dirt on the heat transfer surface of the condenser is serious, and the scale has a great influence on the condensation pressure.
solution:
Air release
2. Increase the water supply and reduce the water temperature;
3. Clean the condenser;
4. Remove excess refrigerant.
Inspiratory pressure is too low
Fault hazard:
The exhaust pressure is too low, although the phenomenon is manifested at the high-pressure end, but the cause is caused by the low-pressure end.
cause of the issue:
1. The expansion valve opening degree is too small, the filter screen is blocked, the orifice ice plug, and the temperature sensing package leakage;
2. The liquid pipe is clogged, the drying filter is clogged, the liquid outlet valve or the solenoid valve is not open;
3. The refrigerant charge is insufficient; the expansion valve hole is blocked, the liquid supply is reduced or even stopped, and the suction and discharge pressures are reduced at this time.
4. The evaporator frost layer is too thick;
solution:
1. Adjust the expansion valve to troubleshoot, clean the filter and remove moisture;
2. Eliminate blockage or open the valve;
3. Add refrigerant (according to regulations)
4. Correct defrost.
Liquid blow (cylinder abnormal sound)
Fault hazard:
The valve piece is broken, the limit plate bolt is loose, the connecting rod and the crankshaft are broken, the cylinder head pad is broken, and the valve plate is damaged.
cause of the issue:
1. The refrigerant does not evaporate sufficiently in the evaporator, and the refrigerant liquid enters the cylinder;
2. The expansion valve is opened too large;
3. Excessive lubricant in the system;
4. Refrigerant migration and solenoid valve closure are not strict.
5. The compressor starts with liquid.
solution:
1. Check the configuration of the evaporator, adjust the matching of the refrigeration system, ensure the return superheat, or install the gas-liquid separator;
2. Adjust the opening degree of the expansion valve.
3. Adjust the piping to make the oil return to normal and release excess oil;
4. Adjust or replace the solenoid valve;
5. Check the crankcase heater.
The exhaust temperature is too high
Fault hazard:
The valve plate is carbonized, piston, piston ring, and cylinder are worn.
cause of the issue:
1. The high pressure is too high and the low pressure is too low;
2. Inspiratory superheat is too large;
3. Shut-off valve or system refrigerant leakage;
4. Cylinder head gasket breakdown.
solution:
Adjust the system's return air superheat;
Check the leak point and replenish the refrigerant;
Replace the cylinder head gasket.
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