Velocity more efficient than volume?

In summary, the conversation discusses the use of equations to calculate the energy output of water based on volume and velocity. It is suggested that using velocity over volume would be more efficient, but there are practical limitations such as the need for sufficient water depth to maintain pressure. The example of a hydroelectric system using flumes and pipes to generate energy from a river with a steep drop in elevation is mentioned as an example of utilizing velocity over volume.
  • #1
drewman13
9
0
Here are two equations showing a nearly equivelant energy output for a given volume and velocity of water. Using the formula:

EKin = M/2 x Vsquared

250/2 x 15.34m/s x 15.34m/s = 29,414 KW (requires 5 times more volume)

50/2 x 35m/s x 35m/s = 30,625 KW (requires only 2.3x more velocity)

Since the velocity is squared, isn't it better to look to use velocity over volume? IF velocity can be acheived through another means other than water pressure via water depth, wouldn't that be the most efficient way to go?
 
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  • #2
Mathematically, yes, it is.

Practically?
[tex]v \propto \sqrt{h}[/tex]
where h is the height of the water and pressure
[tex]p \propto \rho g h [/tex]
This depends on desinty of water and height. If you want to double velocity, you'll 4x the height, which 4x the pressure...It'd be a challenge to find material that can withstand that...
 
  • #3
drewman13 said:
Here are two equations showing a nearly equivelant energy output for a given volume and velocity of water. Using the formula:

EKin = M/2 x Vsquared

250/2 x 15.34m/s x 15.34m/s = 29,414 KW (requires 5 times more volume)

50/2 x 35m/s x 35m/s = 30,625 KW (requires only 2.3x more velocity)

Since the velocity is squared, isn't it better to look to use velocity over volume? IF velocity can be acheived through another means other than water pressure via water depth, wouldn't that be the most efficient way to go?

Water depth? You will still have to get the water to a sufficent height above the outlet in order to get the pressure. You will also have to refill this depth of water in order to maintain pressure. That means using energy to get all this water from the working level to the top.

Are you thinking that you can just put a hose deep in the ocean and water will flow up to land with the pressure from the depth? I hope not
:frown:
 
  • #4
Why do you suppose they build dams as high as they can? The hydro electric system on the Umpqua river in Southern Oregon, does not have many high dams. They use a system of flumes to carry the water to top of a several hundred ft high cliff, then using huge pipes (8' to10' in diameter) drop the water at a high velocity into the generators and back into the river bed. This is a convenience of our local geography, and a relatively small river that drops rapidly from 5000' to near sea level in less then 50 mi.

http://www.outstandingrivers.org/northumpqua.asp
 
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FAQ: Velocity more efficient than volume?

What is the difference between velocity and volume?

Velocity refers to the speed at which an object is moving in a specific direction, while volume refers to the amount of space an object occupies.

How is velocity more efficient than volume?

Velocity is more efficient than volume because it takes into account the direction of movement, allowing for more accurate and precise measurements and calculations. Volume, on the other hand, only considers the amount of space an object occupies without taking into account its direction of movement.

Can you give an example of how velocity is more efficient than volume?

One example is in the transportation industry. A train's velocity, or speed and direction, is more important than its volume, or the amount of space it takes up on the tracks. This is because a train needs to reach a certain velocity in order to travel efficiently and reach its destination on time, while the volume of the train does not affect its speed.

How does understanding velocity help in scientific research?

Understanding velocity is crucial in scientific research as it allows for more accurate and precise measurements and calculations. In fields such as physics and engineering, velocity is a key factor in understanding the behavior and movement of objects. Without taking velocity into account, the results of experiments and studies may be inaccurate or incomplete.

Is velocity always more efficient than volume?

No, there are certain situations where volume may be more important than velocity. For example, in the field of fluid dynamics, understanding the volume of fluid flowing through a pipe is more important than its velocity. It is important to consider the context and specific variables in order to determine which is more efficient in a particular situation.

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