CFX domain reference pressure
 

Even though pressure BCs are imposed in CFX-setup, additionally if I keep some reference pressure value in CFX-domain setting , will it help in better pressure prediction in solution.

Since I use reference pressure, I recalualted the gauge pressure value and imposed @ inlet
# Note pressure units are in [psi]

I do not understand your question.

But if you are asking about how to set the reference pressure - there are lots of threads on this topic on the forum, do a search to find them.

Is it better to provide some value in reference pressure instead of keeping it as zero.

Yes. It is important that the reference pressure is a typical absolute pressure value in the simulation to minimise numerical round off errors.