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Trane RTWB low pressure oil

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grinroman

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Discussion starter · #1 ·
We have a problem with the screw compressor on the chiller RTWB212. Low oil temperature on the return to the compressor (30-35 degrees Celsius) and generally low cooling capacity. The current load goes up, but the compressor is not actually loaded. We assume that the compressor has insufficient oil flow in the oil system. The oil and filter on this chiller was changed 2 years ago. Checked the correct assembly of all things (solenoid valves, all gaskets, screens). The pressure on the shredder on the oil filter is 0.5 bar below the discharge pressure. Oil pressure is low. The tube at the outlet of the oil separator is already almost cold, and the discharge temperature after the compressor is 60 degrees Celsius.
We have a suspicion that the oil valve, which is after the filter, is not working properly, but we are not sure...
What can be your recommendations and advice on our problem?
Thank you!
 
Discussion starter · #7 ·
Oil temperature 30-35 degrees Celsius, (normal oil temperature should be 50-60 degrees Celsius), condenser saturation temperature 45-47 degrees Celsius.

The glycol temperature difference between the inlet and outlet on the evaporator is only 0.5 degrees when this circuit is operating.
However, the other circuit on the same chiller has no such problem. At a condenser saturation temperature of 45 degrees Celsius, the oil temperature is about 60 degrees Celsius, and the difference between the glycol inlet and outlet in the evaporator is 2.0 degrees.
The glycol set point is 5.0 degrees Celsius
 
Discussion starter · #9 ·
Yes, this chiller has a heat exchanger to cool the lubricating oil. There is not much difference between the temperature of the lubricating oil at the inlet to the cooler and the temperature after the cooler. The oil cools abnormally fast in the oil separator.
Oil pressure is low.
Due to low oil pressure, the charging piston does not work properly and therefore the cooling capacity is low. At the same time the load percentage on the controller screen is increasing (most likely the current consumption is increasing due to insufficient lubrication of the screws and bearings).
 
#10 ·
condenser inlet and outlet temperature?
discharge temperature?
suction pressure/discharge pressure?
remember that these machines do not have an oil pump and the lubrication is by differential pressure of the system
 
Discussion starter · #11 ·
On the condenser:
on glycol line: inlet 32 Celsius, outlet 34 Celsius.
on freon line: gas inlet to condenser 60 Celsius, liquid outlet from condenser 40 Celsius.

Discharge temperature 60-65 Celsius.

Suction pressure 2 bar, discharge pressure 11 bar.
 
Discussion starter · #13 ·
Our RTWB chiller does not have an oil pressure sensor, but we were able to connect through a fitting and measure the oil pressure. The oil pressure is 4 bar. In our opinion the oil pressure is low.

The temperature of the glycol in the evaporator :
set point 5 degrees celsius.
As I wrote above, the temperature delta on the evaporator is low (0,5 K) when this compressor is running. When the second compressor is running, the temperature delta is about 2 K
 
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grinroman
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