Hi there

hope everybody is fine.
I'd be very grateful if somebody could give me some hint concerning following topic.

I have a refrigerant desuperheater that... whistles !

My impression is that this is due to too high velocity in the refrigerant pipes.

I have calculated a refrigerant velocity of almost 52 m/s in the model headers.
Moreover, there is a section reduction (a sudden restriction) from the refrigerant line to the desuperheater header of 2 times the diameter.

Please, has anybody from you ever faced to a similar situation ?
Is there somewhere a rule of thumb to design correctly the header ?

Thanks !