Lubricant will flow circularly in and out of compressor while transport refrigeration unit is in operation and refrigerant is being discharged and flows circularly. So where refrigerant flows through, there will also have lubricant flow through.

The functions of refrigerant and lubricant are totally distinct. Refrigerant will change in the state of liquid and gas in circulation while lubricant only stays in the state of liquid. When refrigerant changes from liquid to gas, lubricant will be separated from it. And this situation will cause a little lubricant remaining in some inner parts of transport refrigeration unit and unable to flow back to compressor. Then there will be shortage of lubricant in scroll compressor, if such condition could not be detected and coped with timely, it will further lead to severe wear on spare parts of compressor and dramatically decrease the lifespan of compressor.

So what cause lubricant backflow relative problems in compressor?

1. Ensure sufficient amount of lubricant

Thus lubricant will normally flow back to compressor and the frequency of lubricant supplement will be decreased.

2. Ensure discharged lubricant flow back to compressor

Ensure flow velocity of refrigerant in suction hose at 6m/s to allow lubricant flow back to compressor. Noticed that max velocity should not above 15m/s to minimize pressure drop and flowing noise. Horizontal hose shall be tilted downward along with flowing direction of refrigerant, the angle is about 0.46^。.

3. Excess remaining of lubricant in heat exchanger shall be prevented. Such problem will cause bubbles in lubricant and superfluous lubricant discharge from compressor.

The aperture size and viscosity of lubricant may also lead to malfunction of lubricant backflow, some of lubricant will remain in gas-liquid separator.

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Zhengzhou Corun. Tech. Co. Ltd., & Corunclima

With nearly 20 yrs’ exp. in R&D and manufacture in transport refrigeration unit and all-electric air conditioner, Corunclima gradually evolves from manufacturer to professional consultant of eco-friendly, cost-effective, customizable transport cooling solution.