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Forum Index : Other Stuff : Micro Hydro Question
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| floodrod Regular Member  Joined: 08/07/2009 Location: Posts: 70 |
So, I happen to have this water channel on my property that runs 24/7 almost every day of the year. It does freeze in dead winter, and may stop flowing in droughts, but just about every day, it is flowing.. I could certainly increase the flow too by removing all the dead trees and debris that has collected over the years. But before I do so, I have a question. How much water flow is needed to turn an F&P? I do not have water calculation tools, so what is a good way to measure the gallon per minute/speed/incline ? I know the height it drops is decent because the water comes from a highway drain on top of the mountain and works itself into a lake. Any info is appreciated:) |
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| KiwiJohn Guru  Joined: 01/12/2005 Location: New ZealandPosts: 691 |
If you have a lot of fall and not so much water you could use a long pipe and make a high pressure pelton type wheel. Dont forget that with a F&P if the machine is too big for the power available to drive it you can take a saw and cut away some of the stator effectively making a 'smaller' generator. |
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Greenbelt Guru Joined: 11/01/2009 Location: United StatesPosts: 566 |
Hydro power is (Head feet or meters)converted to PSI. Multiplied by the quantity of water flowing by a stationary point using any unit of measure ; Liters, Gallons, Cubic feet. The weight of all water passing through this point is the power available. The important thing is to choose your unit of measure and stick with it. Assume a bucket with a diameter of 10 inches, 25 centimeters, and a height of 30 inches,75cm. filled with water, about 83.4 pounds. How much 2 inch pipe(5)cm. will be needed to contain 83.4 pounds of water ? 231 cubic inches is 1 US gallon, 10 times 231 = 2310 cubic inches, A-2 inch (5)centimeter pipe has a circular area of 3.14 square inches. The above Number 2310 cu. in. When divided by 3.14 results in a pipe length of 736 inches long. 736 inches. divided by 12 = 61.3 feet. 18.7 m. 27.72 vertical inches of water will weigh 1- pound on (each) square inch of surface it is resting on. .If this pipe be supported vertically and fitted with a pressure gauge at the bottom, then filled you would see the gauge reading 26.55 psi. From this statement you can see that it does not matter if the pipe diameter is 25 centimeters or 25 meters, the gauge would still read 26.55 pounds (square inch). The total weight of the water in the pipe is 26.55 X 3.14 sq. inches = 83.37 pounds Head feet is the Height of the water pipe measured in feet, (One head foot is equal to 0.4329 PSI) Another way to calculate Pressure is to use the constant,(2.31 head feet = 1-PSI) Divide vertical height in feet by 2.31 = psi. If a pressure gauge is mounted on the 30 inch bucket it would show 1.08 psi. Note; One US Gallon weighs 8.34 pounds. When you lay the pipe on the natural grade It will form an angle with an imaginary vertical line at the up hill end of the pipe. This fake line extends into the Earth to a depth equal to the level of your turbine, The length of this fake vertical line is your true head feet, so the steeper the hill the less pipe is needed to gain a good head . Question?? will your stream at maximum yearly flow fill a 20 liter container in one second? At medium flow will it produce 8 to 10 liters. and most important, what is average flow over longest time period. A turbine should be sized to perform efficiently using the attributes the site has to offer. What is the legal distance, (property lines, Roads, parks, etc. that you can lay pipe up hill and what elevation in feet, meters, can be obtained.? Within finance limits. If you can get high head then the water flow is secondary and the turbine can be small costing much less. Power = PSI multiplied by Square inches at that pressure directed at the Turbine blades * Turbine radius * 6.28 and multiplied by Turbine efficiency. This will give approximate Torque. When the Flow is known and the Head is known then power can be figured. Send us some info for a little more help. The numbers above are arbitrary and are used to illustrate the basics of hydro power. ALL PERSONS INVITED TO JUMP IN AND HELP. "Long winded"  Time has proven that I am blind to the Obvious, some of the above may be True? |
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Don B Senior Member  Joined: 27/09/2008 Location: AustraliaPosts: 190 |
Hi Floodrod There are different types of machines that you can use to recover energy (generate power) from water, depending on the amount of head that you have available. In your open channel, you have only flow (little or no head), so you would have to look at something like a Kaplan turbine, or maybe even a paddle wheel. If you could install a pipe to intercept the water at a higher level, then you could recover more energy (if the pipe was big enough), and maybe then you could start looking at a pelton wheel type machine. You would, however, need to do your sums very carefully for this, as the cost might greatly exceed the benefits. Whatever you use, and particularly if it is a Kaplan type, it will be slow speed, and will almost certainly need a step up gearbox both to increase speed for the alternator, and to get a driveshaft up clear of the water. I have never experimented with this idea, but it might be worth playing with, as it would be relatively simple and inexpensive to set up for a trial. I think that, if you could get and old (and preferably large) outboard with perhaps a stuffed motor, you should be left with a suitable propellor and properly sealed gearbox. All that you would then have to do is attach an alternator to the drive shaft in place of the engine, and you would have a poor man's Kaplan turbine type micro hydro. The alternator could be an F&P, or even an automotive one at a pinch. Most outboards would have a range of propellors available, and you should try and get hold of the slowest (boat) speed one possible (ie the fishing boat rather than the speedboat version), as it will have a lower pitch. Note also that an outboard propellor will actually have its lifting surface on the front of the blade (ie the forward side) so, for best results, you should set it up pointing backwards (ie propellor upstream of the gearbox). Obviously, you could partially or fully block the channel so that most ot all of the water is directed through the propellor. You might have to set up a duct around the propellor for best effect. If the water flow is substantial, then maybe you could use two or more outboards and alternators to get more power. Note that an outboard propellor is a far from optimum turbine blade, so that you would have plenty of scope to get better results with a properly designed blade if the initial results are encouraging. If you try this scheme, I would be very interested to hear the results. Regards Don Don B |
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| HeadsUp Regular Member Joined: 06/12/2009 Location: AustraliaPosts: 43 |
these might help , they have charts to calculate power from head and flow rate build it hydro platypus hydro |
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| cobo351 Newbie  Joined: 18/12/2009 Location: United StatesPosts: 34 |
If you have a lot of drop and a little water you have a good start. You could try making a water wheel about as tall as you as your drop. The bigger the wheel you can make the more torque it will have, the water will be able to fill more reservoirs and they will be further from the center. Think of holding something close to your body then trying to hold the same thing at the end of a stick six feet long. If you don't have a lot of water you will want to keep it narrow and channel the water to it. The wheel will be more efficient if you can make it so that it will hold water until the revolution causes it to spill out. I have seen one online somewhere one made from small plastic reusable food containers. I also have a small creek that I’ve been trying to make electric from. It never dries up and never freezes, but I have very little drop and the banks are very far apart. I made a wheel that turns from the current of the creek. Because the diameter of the wheel is small and I have very little drop it doesn’t have much torque. I am thinking of going with something like a Kaplan turbine. I’m wondering if I even have enough drop for that. Cory 
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| Don B Senior Member Joined: 27/09/2008 Location: AustraliaPosts: 190 |
Hi Cory, From what you are saying about the width of your creek, I gather that it would be difficult to dam it completely which would let you use a kaplan turbine (or several of these side by side) to best effect. If this is so, then you are probably best off scaling up your paddle wheel (which looks good in the photo) to be as big as you can make it. As you indicate, the larger the diameter, the greater the torque that you will get. It would also be true to say that the larger the submerged paddle area, the greater the torque for a given wheel diameter and stream flow. Unfortunately though, the larger the wheel diameter, the slower it will turn for a given stream speed. Power is a function of torque multiplied by speed, so that there is a down side to slow rotation. This did not stop factory owners in days of yore from diverting streams (or some part of a river flow) through a channel, and having a series of paddle wheels of 3 metres or so diameter just dipping into the channel and driving grinding mills , etc . Several of these wheels are still operating in France today, although most do no useful work except for attracting tourists (Ille sur la Sorque, Avignon, etc). There is an actual operating wheel in a paper mill in France at a place called Fontaines de Vaucluse, still with its original wooden gears, etc. Fascinating, but high maintenance. I think that you would be better to stick to modern gearing if you want to make useful power. Regards Don B |
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| cobo351 Newbie Joined: 18/12/2009 Location: United StatesPosts: 34 |
Thanks for the reply Don. You are right on about it being difficult to dam. The banks are about 30 to 50 meters apart, and the ground on each side of the creek is loaded with trees and swampy. I will post an overview picture of the creek showing the banks on each side. The latest attempt with the wheel installed is giving me about 4 inches of drop behind the wheel. Another idea I’m thinking about is using pipe or drain tiles with propellers installed similar to a Kaplin style turbine. I can control the flow of the water as long as I don’t try to dam it too much. If the pressure ahead of the dam is too great the forces its way around the dam in an area that is very hard to plug off. This is a project I really can’t wait to get started on again this spring. Being that there is a large amount of water that flows 24 hours a day there is good potential to create electricity. Doing so on a low budget makes doing so more challenging. Oh here is another thing I’ve read a little about online, using the flow of the creek to operate a ram pump. Pumping water to an elevated height to spill into a tall narrow Palton style wheel. Thanks, Cory |
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