Stored Energy in a pressure vessel

In summary, the conversation discusses using a small timestep to approximate the energy lost when releasing compressed natural gas from a tank, and the possibility of equating this to the change in stored energy in the tank. The question of whether pressure and volume can be used to model stored energy is also raised. The possibility of an isochoric process is mentioned, and the distinction between work and stored energy is clarified.
  • #1
boka33
9
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Consider a problem where a tank holds compressed natural gas, compressed to approx. 250 times atmospheric conditions.

Now release the tank valve letting some of the gas out.

Assuming a small timestep, I can approximate the energy lost as 1/2 mv^2,

where m is the mass released during the timestep, and v is the (assumed constant for small timestep) velocity of exiting gas.

Can I equate this to the change in stored energy in the tank during this timestep with reasonable accuracy?

If so, can I model the stored energy as E = PV

where P is pressure in the tank and V is the volume.

Thanks alot.
 
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  • #3
I think the difference is that I was assuming an isochoric process, since a tank of fixed volume held the process. Maybe this is not the case? Either way, it should be noted that in my case I am just looking for a valid approximation, so I do not wish to model a differential problem. I have been using timesteps.

So if isochoric is assumed

Work = PdV = 0

But I am looking at stored energy, not work done, this is where I am confused.
 
Last edited:

1. What is stored energy in a pressure vessel?

Stored energy in a pressure vessel refers to the potential energy that is stored in the form of pressurized gas or liquid inside the vessel. This energy is created by compressing the gas or liquid, and it can be released to perform work or generate power when needed.

2. How is stored energy calculated in a pressure vessel?

The stored energy in a pressure vessel can be calculated using the formula: Stored Energy = Pressure x Volume. This formula takes into account the pressure of the gas or liquid inside the vessel and the volume of the vessel itself. The unit of measurement for stored energy is joules (J) or in some cases, foot-pounds (ft-lb).

3. What are the potential hazards of stored energy in a pressure vessel?

The potential hazards of stored energy in a pressure vessel include explosions, leaks, and ruptures. If the pressure vessel is not properly designed, installed, or maintained, it can lead to a catastrophic failure that can cause serious injuries or damage to the surrounding environment.

4. How is stored energy released from a pressure vessel?

Stored energy can be released from a pressure vessel through various methods, such as opening a valve, removing a plug or cap, or using a release mechanism. The method used will depend on the design of the vessel and its intended purpose.

5. What safety measures should be taken when working with stored energy in a pressure vessel?

When working with stored energy in a pressure vessel, it is important to follow all safety protocols and procedures. This may include wearing protective gear, ensuring the vessel is properly secured, and using appropriate tools and equipment. It is also important to regularly inspect and maintain the vessel to prevent any potential hazards.

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