Question about screw compressor

[skyboy6142]

Dear Friends,

Would you please make it clear for me ?

1 – I know we have discharge port in screw compressors instead discharge valve in semi-hermetic compressors, I know in industrial compressors we can change location or diameter of this discharge port to change Pi or Vi.
I have a question, In commercial brands such as Bitzer CSH compressors, Also can we change this port location or it is fixed ?

2 – Next question, A screw compressor can have Slide valve and Discharge port position changeable both of them ? Or if compressor have slide valve then discharge port would be fix ?

I will be very thankful if you make it clear for me.

Thanks.

[RANGER1]

Sky boy,
Some information on the subjects.
Discharge port is fixed, slide valve port is variable.
Bitzer only seem to make variable Vi from certain size upward.
Frick paper also explains volumetric efficiency.

https://nextcomp.ca/wp-content/uploa...er-Digital.pdf

https://www.bitzer.de/shared_media/d...600-1-en-2.pdf

http://www.hanbell.com/product/rc2avi-tm.pdf

[skyboy6142]

Thanks Ranger