Steinaman,
Interesting site. Thanks for posting the pictures. I don't have any direct experience with this type of low-head, high-flow microhydro, but I have a few thoughts... First, you might as well forget about a pelton turbine, you don't have the head for it and even if you had a bit more, the runner would need to be huge to handle the flow you have. What you need is a reaction turbine, like a Kaplan or propeller type. Check out www.waterturbine.com for some "micro" scale commercially available reaction turbines. Could you build a small building on top of the "weir tower" to house the turbine and generator, with a draft tube extending down 10'? You'd have to build up the weir on 3 sides (or knock out one side a bit) to channel all the flow into the intake. I'm not sure how you'd design the intake and screening arrangement , but perhaps Bob at Hydroscreen could help.: www.hydroscreen.com The water diversion idea you mention might turn out to be an easier way to go if you can channel the flow into a penstock that drops steeply over the edge of the bank or dam. I think the reaction turbine could be mounted either above or below the drop. Good luck, and keep us posted! Eric ----- Original Message ----- From: "steinaman" [EMAIL PROTECTED] To: <[email protected]> Sent: Monday, April 04, 2005 9:08 AM Subject: [microhydro] Site evaluation - advice wanted > > > > Site evaluation - help wanted > (a folder by that name has been created for reference) > Given this site, whats easist design to install and maintain? > > An Engineering problem: > (I had posted this previously but got minimal response. > I hope I simplified the description enough for more feedback.) > I have a good site, but not enough knowledge/experience to use it. > My concerns are less to do with the electronics than with the site > 'engineering'. > How best to select the proper turbine, place it and channel flow to > it. > How to do it in a low impact, low cost and best ROI way with long life > and low maintenance. > Once that's more clear to me I can focus on the wiring issues. > This would serve a rural/suburban home about 100 yards away which > currently uses about 1000 KWH per month. Would prefer to 'offset or > feed the grid' at first and consider batteries at a later date. > > DESCRIPTION: (in Northern Ct., USA) > A one acre manmade (1960s) pond, 17 ft at deepest, fed by two > streams, > which outlets through a vertical concrete wier on the dam side. > The dam is earthen, the wier is built like a fireplace/chimney > structure standing about 14 feet into pond from the dam base, > which is about 12' deep water at that point. (pics in folder) > Water flows in at the top through trash rack and exits from the base > thorugh a 24" concrete pipe running out of the dam base. > > The 30"x24" trash grate at the top has a perimieter of 108". > All flow goes through that , nearly year round. > Flow over this varies from zero(some, not all Augusts) to 3" most > winters. > I have used wier calculations and the 108" pereimeter to find the > flow varies from 0 to 1700 GPM. > Lets say it averages 600 over a year. > There is a 10' drop inside the concrete structure. > This is the maximum head I can achieve on my property. > > Here are my primary questions: > - is my math right? I am not sure the standard 'wier' calculations I > see, all illustrated as a board in a stream, apply here. > I.e. do I calculate flow potential correctly? > (see folder's excel file 'Hydrocalc.xls') > In that file I calculate between 600 to 3200 watts/sec (gross) > at low (300 GPM) to maximum(1700 GPM) flows. > > - which turbine type and placement gains most from this setup? > Optimum solutions avoid draining the pond for installation, > but that's not out of the question. > -do I construct a flow diversion to concentrate woter flow over > a pelton turbine installed in bottom of wier to gain the most > available head, or > -do I mount a flow through turbine at top, or > -do I adapt the outlet pipe to take power from the concentrated > flow there. > -do I drill a pipe through base of wier to feed nozzle(s) against > a pelton wheel installed down there with the force applied by > 1 acre of pond surface 10 ' above. > -do I increase pressure and gained energy output by channeling > the 108" of flow through a pipe or sluice to the turbine? > or does channeling only help me attain the maximum potential of > the calculations? > > Besides obvious differences in installation logistics are there > major tradeoffs in achieved output? > > I think those are the most important issues for me to begin with. > thanks to all in advance. > Feel free to send directed reply ([EMAIL PROTECTED]) if you dont wish > to do broadcast posting. > > > > > > > > > > Does your company feature in the microhydro business directory at > http://microhydropower.net/directory ? If not, please register free of > charge and be exposed to the microhydro community world wide! > > NOTE: The advertisements in this email are added by Yahoogroups who > provides us with free email group services. The microhydro-group does not > endorse products or support the advertisements in any way. > > More information on micro hydropower at http://microhydropower.net > > To unsubscribe: send empty message to > [EMAIL PROTECTED] > Yahoo! Groups Links > > > > > > > > ------------------------ Yahoo! Groups Sponsor --------------------~--> In low income neighborhoods, 84% do not own computers. At Network for Good, help bridge the Digital Divide! http://us.click.yahoo.com/EA3HyD/3MnJAA/79vVAA/FGYolB/TM --------------------------------------------------------------------~-> Does your company feature in the microhydro business directory at http://microhydropower.net/directory ? If not, please register free of charge and be exposed to the microhydro community world wide! 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