Pressure Energy Transfer From 1 Tank to Another 1

In summary, the conversation discusses the energy required to move compressed air from one tank to another. The amount of energy needed depends on factors such as temperature and pressure. Opening a valve between the tanks will result in some energy loss to friction and heat. Additionally, cooling the tanks can reduce the energy loss, but further cooling may require more energy. The calculation for the amount of energy needed to transfer the compressed air is based on the initial and final pressures and temperatures of the tanks.
  • #1
genergy
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When I have a full tank of compressed air that I need to move to another tank will it require the same amount of energy that it took to compress it to move it?
2 -- 318 cubic feet (equal volume) compressed air tanks are side by side.
One is full at 312 psi and the other is at atmospheric pressure.
I know that if I open up a valve between the 2 that I am able to transfer half of the compressed air and lose some energy to friction/heat.
How much energy will it take me to move the last half of compressed air over?

312 psi / 2 = 156 psi x .9 = 140 psi (assuming 10% lost in friction/heat)

How much energy to compress/move the 318 cubic feet of air at 140 psi over to the other tank?

Will cooling help to reduce the energy loss?

http://gravitybuoyancy.com/g_energy/Conserving_Air_Compressor_Energy.html
 
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  • #2
genergy said:
When I have a full tank of compressed air that I need to move to another tank will it require the same amount of energy that it took to compress it to move it?
2 -- 318 cubic feet (equal volume) compressed air tanks are side by side.
One is full at 312 psi and the other is at atmospheric pressure.
I know that if I open up a valve between the 2 that I am able to transfer half of the compressed air and lose some energy to friction/heat.
Initially it will transfer rather less than half. This is because the decompressing tank will cool and the other will warm, so equilibrium pressure will be reached before half of the gas has been transferred. You'll get 50-50 when the tanks return to ambient temperature.
How much energy will it take me to move the last half of compressed air over?
Depends how much of a hurry you're in. As above, the receiving tank will warm and increase resistance to further transfer.
312 psi / 2 = 156 psi x .9 = 140 psi (assuming 10% lost in friction/heat)
Judging from that calculation, the 312psi is additional to atmospheric. But I don't understand the 0.9. There's no loss of air, so if the initial and final temperatures are the same it should be 156.
How much energy to compress/move the 318 cubic feet of air at 140 psi over to the other tank?
To compress a volume V0 at pressure P0 to vol V1 at P1, constant temperature (i.e. slowly) would take energy P0*V0*ln(V0/V1) = P0*V0*ln(P1/P0)
So if you have two tanks vol V, pressure Pm = (Ph+Pa)/2, and you want to end up with one at Ph and the other at Pa (atmospheric), the energy required is V(Ph ln(Ph/Pm) + Pa ln(Pa/Pm)).
All pressures are absolute here.
With your numbers, that's 318*(326 ln (326/170) + 14 ln(14/170))*144 = 8*106 foot-pound-weight. That seems rather a lot, so maybe I have something wrong.
Will cooling help to reduce the energy loss?
Allowing to cool to ambient, yes. Any additional cooling will come at an energy cost, almost surely exceeding what you save.
 
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Related to Pressure Energy Transfer From 1 Tank to Another 1

1. What is pressure energy transfer from 1 tank to another 1?

Pressure energy transfer from 1 tank to another 1 is the process of transferring energy in the form of pressure from one tank to another. This is usually done through the use of pipes or hoses connecting the two tanks.

2. How does pressure energy transfer work?

Pressure energy transfer works by utilizing the principle of fluid dynamics. When a fluid is under pressure, it will naturally flow from an area of high pressure to an area of low pressure. This allows the energy to be transferred from one tank to another.

3. What factors affect pressure energy transfer?

The factors that affect pressure energy transfer include the size and shape of the tanks, the type of fluid being transferred, the pressure difference between the tanks, and the flow rate of the fluid.

4. What are the benefits of pressure energy transfer?

There are several benefits of pressure energy transfer, including the ability to transport large amounts of fluid quickly and efficiently, the ability to transfer energy over long distances, and the ability to control the flow rate of the fluid.

5. Are there any safety considerations with pressure energy transfer?

Yes, there are safety considerations with pressure energy transfer. It is important to properly monitor and control the pressure and flow rate to prevent any accidents or damage to the tanks or surrounding equipment. It is also important to use proper safety precautions, such as wearing protective gear and following proper procedures, when handling and transferring the fluid.

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