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#### iqballud

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##### Dynamic Pressure Calculation
« on: February 22, 2017, 12:15:05 PM »

Hi,
If the gas quantity will be transferred from upstream to downstream of control valve, then the pressure in the downstream control valve will be increased.

How to calculate (as dynamic calculation) downstream pressure (gas) from control valve if the upstream control valve having data as below:
P (bar.a) = 70; T (oC) = 40; MW =20.1; Density (kg/m3) = 60.
And this is the downstream control valve data, volume (m3) = 1350. This is included the pipe and vessel.

To calculate gas flow through control valve, can we use this formula:
QG = Cv*816*P1 / SQRT (Sg * T)

Regards,
Iqballhud
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#### iqballud

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##### Re: Dynamic Pressure Calculation
« Reply #1 on: February 22, 2017, 11:08:09 PM »

If the total gas flow on the downstream 200 m3, how much pressure will be increased?
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#### militarymaid

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##### Re: Dynamic Pressure Calculation
« Reply #2 on: February 25, 2017, 07:28:46 PM »

Alright I am too lazy to make a balance on 12:25am buuuut I can tell where the problem is telling you to go.
First you need to propose the momentum balance with the Navier Stokes equation, from the moment it goes in and the moment it goes out. Do not consider the derivatives of time to zero instead propose the quantities they are giving you to make the equation simpler.

Once you get a nice differential equation you solve it... Which I recommend you eigenvalues, usually momentum differential equations are solved very easily with that method.
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