- #1
paul turbine
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I think it is possible to design a machine capable of generating useful electricity using recirculated fluid flow. But the laws of thermodynamics make it very difficult.
The three laws of thermodynamics can be summarized by saying: "You can break even but only at absolute zero".
So we know for sure we will never be able to get more energy out of a system than we put into it in the first place.
Secondly, the value of entropy in a system governs what is possible or impossible.
If entropy is zero or negative, then whatever we had hoped to achieve is impossible. It is simply not permitted by the laws of physics that govern the universe.
An example would be trying to reverse the smashing of an egg on the floor. A reversal of the process (where the egg lifts off the floor and recombines into a pristine egg)would require a negative value for entropy (S). Accordingly, we can be certain a reversal of the process is impossible.
Unfortunately, the laws of thermodynamics and the related law concerning entropy constitute reality. If we don't like it, we will have to go and live in another universe.
Bearing in mind the laws we are stuck with, the next step is to think about what types of system might be useful for generating electricity, bearing in mind these serious limitations.
There are three types of systems. Isolated, closed and open systems.
In isolated systems, neither mass nor energy can pass through the system boundaries (think of a perfectly insulated thermos flask).
We will never generate useful electricity from an isolated system. For a start we won't get any energy out of it in the first place. If we could, it would not be an isolated system.
So we can forget about isolated systems.
What about closed systems? They allow energy to pass through system boundaries, but prevent mass passing through them. Think of a badly (thermally) insulated thermos flask that is perfectly airtight and watertight.
The problem with closed systems is that you always get less energy out of them than you put into begin with.
Our only hope is an open system in which both mass and energy can pass through the system boundaries.
So this has to be our starting point.
We must invent a machine that allows mass to pass in and out of the system boundaries, and also allows energy to do so as well.
In practical terms this means we need help from the environment.
External work must be done on the system (eg solar energy or water from a flowing stream) to provide energy from outside the system boundary.
External mass (eg air or water) from outside the system boundary must be able to pass through the boundaries as well.
The best idea I can come up with as to how we can generate useful electricity using fluid flow began as a thought experiment:
There are two 25m high cylinders each of diameter 1m (only the most intrepid amongst you will want these things in your back garden, so they are intended for industrial use).
Cylinder A is full to the brim with water.
Cylinder B is 10% full of water.
An impulse turbine (for example a Pelton turbine) is placed 3m from the bottom of cylinder B (allowing a space beneath it for tailgate water to accumulate).
The cylinders are connected to one another such that water flows from A to B, allowing it to fall down a 20m+ drop in cylinder B before striking the impulse turbine.
At a mass flow rate of one cubic meter per second (which is an enormous flow rate) and allowing for system efficiency of 0.85 (this being a unit-less fraction where 0= total inefficiency and 1= perfect efficiency), the electrical power output in watts (using water of density 1000kg/m3 as the working fluid) is as follows:
Pw = 1000kg/m3 x 20m x 9.81 m/s/s x 0.85
Pw = 166770 watts = 166.77kW.
So this looks promising.
But there are serious practical problems.
Water that collects at the bottom of cylinder B (the tail-gate water) will rise until the point it prevents the impulse turbine turning. It will swamp the turbine and stop it moving.
So the water that builds up at the base of cylinder B has somehow got to be forced back into the base of cylinder A (which requires energy expenditure because of the higher water pressure at the base of cylinder A).
I think I have found a way of recirculating the water without having to use enormous amounts of external energy (to lift or pump fluid back into tank A).
I would much appreciate private (not to be published) dialogue hopefully with a co-inventor familiar with thermodynamics, Bernoulli, and Newtonian fluid flows.
Preferably a doctorate in applied physics/fluid dynamics.
My aim is to share an energy efficient recirculation novelty, test same using a comprehensive parametric equation, and apply for a patent relating to industrial electricity generation.
I can be contacted at:
<< personal e-mail deleted by berkeman >>
Thanks for reading the post. I hope you enjoy thinking of your own solutions to the problem as much as I have done.
The three laws of thermodynamics can be summarized by saying: "You can break even but only at absolute zero".
So we know for sure we will never be able to get more energy out of a system than we put into it in the first place.
Secondly, the value of entropy in a system governs what is possible or impossible.
If entropy is zero or negative, then whatever we had hoped to achieve is impossible. It is simply not permitted by the laws of physics that govern the universe.
An example would be trying to reverse the smashing of an egg on the floor. A reversal of the process (where the egg lifts off the floor and recombines into a pristine egg)would require a negative value for entropy (S). Accordingly, we can be certain a reversal of the process is impossible.
Unfortunately, the laws of thermodynamics and the related law concerning entropy constitute reality. If we don't like it, we will have to go and live in another universe.
Bearing in mind the laws we are stuck with, the next step is to think about what types of system might be useful for generating electricity, bearing in mind these serious limitations.
There are three types of systems. Isolated, closed and open systems.
In isolated systems, neither mass nor energy can pass through the system boundaries (think of a perfectly insulated thermos flask).
We will never generate useful electricity from an isolated system. For a start we won't get any energy out of it in the first place. If we could, it would not be an isolated system.
So we can forget about isolated systems.
What about closed systems? They allow energy to pass through system boundaries, but prevent mass passing through them. Think of a badly (thermally) insulated thermos flask that is perfectly airtight and watertight.
The problem with closed systems is that you always get less energy out of them than you put into begin with.
Our only hope is an open system in which both mass and energy can pass through the system boundaries.
So this has to be our starting point.
We must invent a machine that allows mass to pass in and out of the system boundaries, and also allows energy to do so as well.
In practical terms this means we need help from the environment.
External work must be done on the system (eg solar energy or water from a flowing stream) to provide energy from outside the system boundary.
External mass (eg air or water) from outside the system boundary must be able to pass through the boundaries as well.
The best idea I can come up with as to how we can generate useful electricity using fluid flow began as a thought experiment:
There are two 25m high cylinders each of diameter 1m (only the most intrepid amongst you will want these things in your back garden, so they are intended for industrial use).
Cylinder A is full to the brim with water.
Cylinder B is 10% full of water.
An impulse turbine (for example a Pelton turbine) is placed 3m from the bottom of cylinder B (allowing a space beneath it for tailgate water to accumulate).
The cylinders are connected to one another such that water flows from A to B, allowing it to fall down a 20m+ drop in cylinder B before striking the impulse turbine.
At a mass flow rate of one cubic meter per second (which is an enormous flow rate) and allowing for system efficiency of 0.85 (this being a unit-less fraction where 0= total inefficiency and 1= perfect efficiency), the electrical power output in watts (using water of density 1000kg/m3 as the working fluid) is as follows:
Pw = 1000kg/m3 x 20m x 9.81 m/s/s x 0.85
Pw = 166770 watts = 166.77kW.
So this looks promising.
But there are serious practical problems.
Water that collects at the bottom of cylinder B (the tail-gate water) will rise until the point it prevents the impulse turbine turning. It will swamp the turbine and stop it moving.
So the water that builds up at the base of cylinder B has somehow got to be forced back into the base of cylinder A (which requires energy expenditure because of the higher water pressure at the base of cylinder A).
I think I have found a way of recirculating the water without having to use enormous amounts of external energy (to lift or pump fluid back into tank A).
I would much appreciate private (not to be published) dialogue hopefully with a co-inventor familiar with thermodynamics, Bernoulli, and Newtonian fluid flows.
Preferably a doctorate in applied physics/fluid dynamics.
My aim is to share an energy efficient recirculation novelty, test same using a comprehensive parametric equation, and apply for a patent relating to industrial electricity generation.
I can be contacted at:
<< personal e-mail deleted by berkeman >>
Thanks for reading the post. I hope you enjoy thinking of your own solutions to the problem as much as I have done.
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