pressure drop across a gas mass flow controller

S

Thread Starter

Samer Hamandi

Hi,
I am modelling a gas mass flow controller. In order to calculate the pressure drop across the mass flow controller we should have the following data : the Kv(m3/h), the flow(m3/h), the temperature(k) and the density.

And we know that the value of Kv is given by the constructor as the precise value of water flow in m3/h under an 1 bar drop pressure; in this case Kv corresponds to the maximum opening of the valve.

My question is how can I calculate the drop pressure across the mass flow controller for a unspecified opening of the valve? In fact we know that the opening is variable and the Kv value depends on.

I wish to receive the answer as soon as possible.

With regards,
Hamandi Samer
 
J

James Fountas

Hello Hamandi Samer.

I don't see that you can. You are leaving yourself with at least two unknowns, valve position, down stream pressure, and possibly flow rate. You would have to define enough of your system that you can relate down stream pressure to valve position. This would allow you to treat it as one unknown with respect to flow rate. This assumes your system can be defined that rigidly.

I did it as homework assignment in my senior year. Define your system and know the valve characteristics. I assume you have a working knowledge of fluid dynamics.

James Fountas
[email protected]
 
I don't see that you can. You are leaving yourself with at least two unknowns, valve position, down stream pressure, and possibly flow rate. You would have to define enough of your system that you can relate down stream pressure to valve position. This would allow you to treat it as one unknown with respect to flow rate. This assumes your system can be defined that rigidly.

I did it as homework assignment in my senior year. Define your system and know the valve characteristics. I assume you have a working knowledge of fluid dynamics.
 
Top