How to deal with oil leakage in small water chiller?

　　How to deal with oil leakage in small water chiller?

　　1. There are no traces of oil in the oil separator, that is, the oil is not collected in the condenser, but enters the evaporator through the expansion valve. Oil will stick to the heat exchange copper pipe of the evaporator, causing poor evaporation effect and low evaporator pressure.

　　At the same time, the suction superheat of the compressor is very low, and even the refrigerant liquid is directly sucked in. The temperature of the compressor is very low, and the oil still cannot be separated from the refrigerant. This vicious cycle will cause all the oil to gather in the evaporator. The compressor will make huge noise due to insufficient oil supply, and even the oil level alarm of the unit oil separator will be triggered.

　　2. There are no traces of oil in the oil separator, and all the oil comes to the condenser with the exhaust. If the water temperature continues to drop, all oil will accumulate in the condenser, blocking the expansion valve. Due to insufficient liquid supply, the pressure in the evaporator begins to decrease until the low pressure alarm stops.

　　This is the so-called oil leakage phenomenon. The main reason is the low temperature of the chilled water and the low exhaust temperature. The solution I encountered during the startup process is as follows:

　　a. When the oil level drops, immediately adjust the unit to manual control mode to limit the load of the compressor, such as limiting its energy to over 50%.

　　b. Increase condensation pressure

　　c. Reduce the low pressure alarm value and low pressure shutdown value of the unit to the allowable range to ensure that the unit can operate

　　d. If the oil level is still very low and the pressure inside the evaporator is also very low, consider whether all the oil has run into the evaporator. Check whether there is a large amount of white foam rolling in the sight glass of the evaporator. If so, it indicates that the oil is in the evaporator, otherwise it may be in the condenser.

　　With the above steps in place, the temperature of the cooling water and exhaust gas should rise to below normal levels after about half an hour and start collecting oil:

　　A: Oil in the evaporator. At this point, closely monitor the temperature of the chilled water. Firstly, the flow rate can be appropriately reduced to lower the outlet water temperature, and then the flow rate can be rapidly increased to quickly increase the outlet water temperature of the evaporator. At this point, the water temperature will greatly exceed the saturation temperature of the refrigerant, causing it to boil violently.

　　The refrigerant oil will be absorbed by the compressor driven refrigerant foam. At this time, the exhaust temperature should be reduced, but it should also be far higher than the separation temperature of oil and refrigerant. Return the oil to the oil separator to separate it.

　　Repeat several times and all the oil will return to the oil separator. Repeat several times and all the oil will return to the oil separator. Pay attention to the time interval between each adjustment of water volume, and it is best to raise the exhaust temperature to before the adjustment after each adjustment.

　　B: Oil in the condenser. As long as the unit can operate normally, there is no need to pay too much attention to the water temperature.

　　At this time, the expansion valve should be gradually opened to the maximum (the opening process is too fast to prevent excessive liquid supply from damaging the copper tube of the evaporator), wait for a few minutes until the high and low pressure of the unit are balanced, and then see a lot of white foam from the evaporator liquid sight glass, that is, oil has entered the evaporator from the condenser.

　　As long as step A is repeated, the oil will quickly recover.