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Gas Bladder Tank/Capacitance

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tmo42

Electrical
Joined
Apr 17, 2003
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15
Location
US
Wanted to check a formula. I've got a gas bladder accumulator and I'm trying to verify how to determin the fluid capacitance of the tank. I've been using Po/(Vo*gamma), Po=Precharge Pressure, Vo=Volume at precharge, gamma = cp/cv (ratio of specific heats).

Could anybody tell me if this is correct?
 
I figured this out.

Begin with Vo*Po=V*P for the air.

V = Po*Vo/P

dV/dt = Po*Vo * -1/P^2 * dP/dt = dVair/dt

Q = dVwater/dt = -dVair/dt

Q = Po*Vo/P^2 * dP/dt

So, C = Po*Vo/P^2.

If the predcess is not isothermal, you start with

PoVo^n = P*V^n and arrive at

C = Vo*Po^(1/n) / [n * P^((n+1)/n)]
 
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