what is the nozzle length when two-phase flow PSV sizing conducted?

[phoenixmoca]

Hi, evergone.
When I read a reference material about two-phase flow PSV sizing the term of nozzle length arises several times. It comfuses me a lot to understand the paper very well.
Woulde you like to take a detailed explanation on the term?
Thank you in advance.

 

[PaoloPemi]

which model / standard ?
There are many different models for two phase flow,
just to mention a few included in my copy of Prode Properties,
1) HEM (Homogeneous, equilibrium)
2) HNE-DS (Homogeneous, Non-equilibrium, boiling delay)
3) NHNE (Non-Homogeneous, Non-equilibrium)
4) ....

some of these take in account boiling delay, non equilibrium conditions etc. along PSV / piping etc.

 

[Latexman]

I had not noticed that. Which reference materials (English) speak to the term of nozzle length?

Good luck,
Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water

 

[phoenixmoca]

Pemi&Latexman
Thank you for your reply.
And the reference in which nozzle length occured is attached. Please refer it and look forward to your further comments. Thank you again.

 

[PaoloPemi]

the mentioned (see my previous post) non-equilibrium models, can include a non-equilibrium factor to take in account boling delay and similar behaviour (for additional information, see the paper),
the distribution of Prode Properties includes a Excel page which allows to compare results from different models, for example HEM (Homogeneous-Equilibrium-Model) vs. HNE-DS (Homogeneous-Non-Equilibrium with boiling delay) etc.
I attach a scrreshot to show the differences

In this case, with a initial condition close to a bubble line, there is the so called boiling delay but other non-equilibrium conditions may happen as well...

 

[gguliye]

Dear Sir,
I havent heard about nozzle height, i rather heard about the orifice size.
The case with the orifice size is that it is reduced, not increases. For example in order to pass let's say 200 kg/hr liquid through the given orifice we need E type, while to pass 200 kg/hr 2 phase flow, we will need D orifice. I am talking about mass flux sizing method,
Thanks.
Regards,

 

[casflo]

The nozzle length is the same as the thickness in the orifice plates. Think in a plate with a great thickness where instead a sharp-edge orifice, you drill an orifice with a rounded entrance and a throat diameter lower tan the entrance diameter, at some distance from the entrance. The relation of t/d (thickness/diameter) may be 5 or more. The nozzle length is t.