Screw refrigeration compressor is a volumetric compressor, which depends on the change of volume to compress the gas. Screw refrigeration compressors are divided into single screw compressors and twin screw compressors.

The twin-screw compressor is the use of two screw slots in the body meshing and rotating and with the inner wall of the body and the inner wall of the suction and exhaust end seat, resulting in changes in the volume between the teeth, so as to complete the gas inhalation, compression and discharge process.

1. Abnormal compression ratio

The compression ratio is no stranger to those who know the performance of compressors. The difference between the screw machine and the piston machine is that the piston machine will only be undercompressed, and the screw machine will be overcompressed. So what happens when the compression ratio is large or small?

If the pressure difference is too large or too large, it proves that the system completely deviates from the design value. The main phenomena are: the exhaust pressure temperature is too high, the inspiratory pressure is low, and the temperature is high. The exhaust pressure temperature is too high, the adverse consequences are mainly for the lubricating oil in the system is easy to coking, it is not suitable to form an oil film, can not fully lubricate the rotor, the rotor can not effectively cool down, lubrication, it will block rotation, and then cause motor damage. The suction pressure is low, the suction pressure temperature is high, which mainly affects the motor cooling, and the exhaust temperature is high. The consequences are basically equivalent to high exhaust temperature and pressure. Too small is mainly affected by the wet stroke (tide car, pour frost), the wet stroke resistance of the screw compressor, in fact, the screw machine is more afraid of the wet stroke, if a large amount of liquid back to the compressor, it will cause the dilution of the lubricating oil, the consequence is equivalent to the high exhaust temperature. Of course, the compression ratio is small, and some are caused by serious rotor wear and load failure.

2, compressor overload

Screw machine reported the compressor overload fault, such as this protection is generally caused by the compressor current abnormal, focus on checking the system power wiring problems, to see if there is a lack of phase, phase sequence errors and other related faults, and then check the compressor wiring, such as the compressor U-V, U-W, V-W three-phase voltage value, and finally in the detection of the electric control cabinet wiring is normal. If all tests are normal, you also need to troubleshoot the motherboard.

3, the condenser efficiency is low

The low efficiency of the condenser mainly affects the temperature of the liquid supply and whether the liquid can be formed. We know that the ideal state of the expansion valve is the full liquid supply, so that the efficiency of the system is higher and the cooling capacity is maximum. Moreover, there are basically attached storage on large units, mainly used in oil cooling. Therefore, it is particularly important to maintain the efficiency of the condenser.

The fault is mainly: the cooling mode selection is not correct, the evaporation area is insufficient, the cooling medium is insufficient, and the heat exchange is insufficient, so the main inspection is to check the key fan, pump, fin and so on.

The condensation effect is too good, for example, the ring temperature is low, the condensation effect is too good, resulting in higher efficiency of liquid into the evaporator, at this time, the suction superheat is very low, the expansion valve sensitivity is low, it will cause the boot liquid blow. Or the difference between the exhaust pressure and the suction pressure is insufficient, which is fatal for the screw machine with the pressure difference oil supply.

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