Pumping water versus expulsion

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In summary, there is a formula for calculating the amount of compressed air needed to force water out of a tank, but it may not necessarily require less energy than simply lifting the water out due to potential efficiency losses.
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bgizzle
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Does it take the same amount of energy to lift water out of a tank as it would to force it out using compressed air? For example if there is a cylindrical tank that is 14 meters tall, 10 meters wide and it is filled with water to a depth of 5 meters I know that it takes 44.3e6 joules to lift that water out of the tank. (9800 n/m^3, 25pi, dy, 14-5... solved using integrals) Is there a formula for how much compressed air it would take to force the water out a vent on the bottom of the tank, assuming the tank is surrounded by water (but attached to the bottom so it wouldn't start floating as you pump in compressed air)?

My thought was it would take less energy to force water out because distance traveled would be less. So if say your tank is 1000 feet down and you wanted to pump the water up and out through a pipe or force it out through a vent, the compressed air way might take less energy. How much force of resistance are you meeting from the water outside the tank?
 
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If the water ends at the same height and if we neglect all inefficiencies, it needs the same amount of energy. This is just energy conservation. In a real setup, that pressurized air will give significant losses.
 

What is the difference between pumping water and expulsion?

Pumping water involves using a mechanical device to draw water from a source and move it to a desired location, while expulsion refers to the natural process of water being forced out of a confined space through pressure or gravity.

Which method is more efficient for moving large volumes of water?

Pumping water is generally more efficient for moving large volumes of water as it can be done continuously and at a faster rate than expulsion.

What are the advantages of pumping water?

Pumping water allows for greater control over the amount and direction of water flow, as well as the ability to transport water over long distances.

When is expulsion a more suitable method for moving water?

Expulsion may be a more suitable method for moving water when the volume of water is relatively small and the natural pressure or gravity is strong enough to move it.

Can pumping water and expulsion be used together?

Yes, pumping water and expulsion can be used together in a system to move water efficiently. For example, a pump can be used to draw water from a source and then gravity can be used to expel the water to a lower location.

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