Archimedes screw power generator 2

[tspco]

I was reading about a couple of companies, that are making ac power generator systems.
They use an Archimedes screw with water running through it, a gearbox and a generator, for hydroelectric power generation. I like the concept, it makes sense to me. My question for you guys is this, if I had a large screw conveyor and its associated assemblies, trough and gearbox, do you think the standard dodge torque arm gearbox, could handle the input from the screw to drive a 100kw generator? I have not found the torque requirements for the generator yet. I haven't had time.

Better lives through fluid power.

 

[TheTick]

Convert kW to HP and compare truck specs to generator

 

[chicopee]

User the water horsepower equation for the screw conveyor if you kwnow the amount of water it can displaced and the head to which it must move the water; then, increase result for friction losses and for brake horsepower divide the increase result by efficiency of gear box and compare final result to that of the power plant.

 

[tspco]

Well maybe not, 30 cu ft sec is 13464 gpm, at a 10 foot head that would net 34 HP, =25KW, if I did it right.

Better lives through fluid power.

 

[racookpe1978]

A screw conveyor "works" for elevating water, but it works very inefficiently and only when something else isn't available. (I'm reminded of the 3rd and 4th world farmers trudging an Archimedes screw conveyor to lift irrigation water a few feet up to ditches next to a river. Yes, it works, but like the Plains windmills, they are replaced by mechanical pumps and electric power as soon as it becomes available.)

A screw conveyor works best for slow movement of very stiff fluids (high viscosity) or grains or asphalt or peanut butter or grease. Water is too hard to seal around all of the many feet of sealing surface between the screw as it rotates and the pipe. Conventional waterwheels or water turbines are better for converting "down" motion (any vertical displacement of water) into electric motion (high speed rapidly moving magnets needing close tolerances).

Unlike air, where ducted propellers have been tried many times and have failed as many times, ducted water (ship) propellers are a little better, but still rarely are commercially successful. Inside pumps and turbines, ducted flow has ALWAYS proved more efficient than open flow.

What you will find, if you begin exceeding the resistance of the screw over longer and longer screws that try to turn a generator, is that the water will simply begin spiraling around the screw inside the pipe casing, not turning it the screw. You have to keep reversing the flow -> as in turbine engines and compressors where there is a fixed diaphragm of blades, a rotating stage, a fixed diaphragm, a rotating stage, etc.

 

[Artisi]

Would have to disagree with the "very inefficiently" part of your post, however the rest
Without checking and from memory would suggest efficiency of a well designed and installed unit being used as a pump would be 70% or so. Plus if it's the only way it can be done, then that becomes 100% compared to other methods which don't work.


It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[tspco]

here is a link to one of the sites i was on the other day Link


Better lives through fluid power.

 

[JStephen]

I'm not aware of any advantage to making the screw part move in a tube- just make the tube and screw all one unit and rotate it together. A helix-shaped tube could do the same thing.

This is potentially very efficient, as is a waterwheel. The problem becomes that you have a large heavy piece of equipment generating a small amount of power. If you can funnel the flow, and use a small fast-moving propeller-type turbine, and get similar efficiency, you have a much cheaper piece of equipment, and that seems to be the common procedure.