The maximum temperature and the maximum pressure recorded on the purchased oil injected twin-screw air-end plate, are 110 degrees and 15 bar, respectively and according to its description table, the production pressure range is between 5-15 bar. The problem I face is about using the working fluid with a higher temperature (e.g. 120 ° C) at the pressure of 16 bar. Is there no possibility of applying working fluid with higher temperatures than that of the plate? Do you think that the higher temperature causes the thermal expansion of rotors and their collisions or it only results in the decomposition of oil? It seems that rotors are made of steel. my air-end is rotorcomp EVO3.
Yes, the temperature maximums are there to prevent thermal expansion up to the point that the element seizes.
It’s always better to use higher quality oil to prevent decomposition of oil, and it’s also not advisable to run at these high temperatures continuously. I would say around 80 degrees Celsius is optimal.
Screw elements have a pretty much fixed maximum compression ratio (outlet pressure / inlet pressure) – which is mainly limited by the amount of heat that is generated during compression, and thus the amount of heat that has to be removed – continuously.
For example, oil-free screw compressors have a much lower compression ratio (around 2.5), since there’s no cooling fluid, therefore they are always designed as two-stage machines with intercoolers.
So to make your screw element work for higher pressure than on the nameplate, you will need to find a way to keep temperatures down.
One way could be to increase the inlet pressure, but that might not be very practical.
Hope this helps 🙂