Flow rate discrepancy between upstream and downstream of orifice model.

I am verifying the flow rate before and after orifice model measured by "Flow Rate Sensor".

The target value of flow rate is 13.2 gpm with diffential pressure 2950 psid and orifice model of orifice area is set to get this flow rate.

Simulation Retuls of flow rate

Before orifice: 13.08 gpm

After orifice: 13.26 gpm

Is there any solution or what is the root cause of this discrepancy?

[Torsten]

And you are confident there are clairvoyants in the forum that will be able to answer this with the information you gave ?

Answer 1

[Yifeng Tang]

A diffential pressure 2950 psi sounds big enough to change the density of the fluid. As the density changes, volumetric flow rate can well be different. Mass flow rate should be conserved.

A few things to check:

(1) measure mass flow rate

(2) set up sensors to measure the density before and after the orifice.

(3) if you are using a fluid property block, right click and you can plot the fluid property. See if the density/bulk modulus varies for the pressure range in question.

(4) check with the source of that 13.2gpm reference data, at what condition was it measured. Was that before or after the orifice?