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Re: Guide on How to Develop a Small Hydropower Plant Math question?

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  • Max Enfield
    At 0.7m head a Banki-crossflow is not really a feasible option. Whilst we have boasted that we are able to simultaneously generate electricity and pump water
    Message 1 of 12 , May 1, 2007
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      At 0.7m head a Banki-crossflow is not really a feasible option. Whilst we have
      boasted that we are able to simultaneously generate electricity and pump water
      from a Banki-crossflow turbine running at a net head of 0.7m - this was just a
      novelty. As I recall, when we achieved this the electrical output was about
      40W. I regard 1m to 1.3m as the practical lower limit to running a
      Banki-crossflow.

      It's been at least 15 years since we last directly measured the water to wire
      efficiency of a Banki-crossflow. This was done at our prototype site with a
      head of 1,8m and flow of 30 l/sec. The measured efficiency was 40% - this
      included transmission losses as well as DC to DC converter losses and also
      losses in the belt and pulley transmission.

      Regards,

      Max Enfield
      Planetary Power

      "Simpson, Robert" wrote:

      >
      > We haven't done a direct comparison of a low-cost cross flow option compared
      > to the propeller turbine design we have been working on. The primary aim is to
      > get the propeller design to a suitably mature stage of development. However, I
      > do know of one cross flow scheme of comparable head and flow rate that is
      > achieving approx. 50% efficiency (and I think that includes the electrical
      > machine efficiency). So, that would be comparable to the efficiencies being
      > achieved for our simplified propeller turbines. I'm sure there are other
      > people out there with more data on cross-flows that might be able to
      > contribute to the discussion.
      >
      >
      >
    • acme11_hydro
      Hello Robert, Max: Robert, thank you for coment. I will try to find suitable solution, that will be able to use affordable materials. I would ask only one
      Message 2 of 12 , May 2, 2007
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        Hello Robert, Max:

        Robert, thank you for coment. I will try to find suitable solution,
        that will be able to use affordable materials.
        I would ask only one question if it is possible:
        What min-max specific speed-Ns should I use?

        Max, Thank you for help, but I am working on propeller turbine. Please
        read first posts.



        --- In microhydro@yahoogroups.com, "Simpson, Robert"
        <robert.simpson@...> wrote:
        >
        > Hi Marko,
        >
        > For the head and flow rate you mention, the turbine specific speed
        would probably be too high for direct drive to an induction motor as
        generator. To bring the specific speed of the machine down to what is
        considered an acceptable range for a propeller turbine would mean an
        operating speed of somewhere around 300-400 rpm as a rough calculation
        unless of course you can achieve a higher head (>0.7m) or decide not
        to use all of the available flow rate (<180l/s).
        >
        > As far as literature goes, most of the ones I use are older
        textbooks, such as Nechleba or a couple of other ones written in
        German by Bohl. Again, the theory is for large Kaplan turbines and I
        am in the process of simplifying all this for application to the
        design of simplified pico-propeller turbines.
        >
        > Sorry I can't be of more help at this stage. More to come at a later
        stage.
        >
        > Robert
        >
        >
        >
        >
        >
        > -----Original Message-----
        > From: microhydro@yahoogroups.com
        [mailto:microhydro@yahoogroups.com]On Behalf Of acme11_hydro
        > Sent: 27 April 2007 00:09
        > To: microhydro@yahoogroups.com
        > Subject: [microhydro] Re: Guide on How to Develop a Small Hydropower
        Plant Math question?
        >
        >
        >
        > Hello Robert
        >
        > Sorry for my bed english!
        >
        > I noticed your work before two months,very good performed work.
        >
        > I have next conditions:
        > 1.Head: around 0.70m
        > 2.Discharge: around 0.18m^3/s
        >
        > Desired setting up:
        > 1.propeller installed in plastic elbow pipe, like tubular turbine.
        > 2.blades made from flat plate, similarly you did in your project
        > 3.directly driven induction motor / generator, 6 or 8 poles
        > 4.TSR- tip speed ratio as high as possible
        >
        > I do not know how to construct propeller adapted to generator speed:
        > 1.blade thickness
        > 2.blade angles at inlet and outlet, at known blade number and area
        ratio.
        > 3.hub diameter
        > 4.guide vanes angle
        >
        > Can you tell me, which software or literature can be used for this job?
        >
        > regards
        > Marko
        >
        > --- In microhydro@yahoogro <mailto:microhydro%40yahoogroups.com>
        ups.com, "Simpson, Robert"
        > <robert.simpson@> wrote:
        > >
        > > Hi Joel and Marko,
        > >
        > > I have been working on a research project here at the microhydro
        > centre at Nottingham Trent University, UK, on developing design
        > parameters for small propeller turbines in the picohydro range (up to
        > 5kW) with heads approx. 2 to 5 metres. Over the next few months I am
        > aiming to produce a spreadsheet to guide potential designers/
        > manufacturers. These turbines have been developed as "appropriate
        > technology" for manufacture in developing countries with fixed blades
        > and guide vanes, simplified spiral casing and blade designs to save on
        > cost and manufacturing complexity. Although the efficiencies are lower
        > than more complex designs, the simplifications make them quite
        > cost-effective in terms of $/kW for developing countries. Our
        > prototype turbine in Peru has a 65% mechanical efficiency (5kW, 4
        > metre head) and more information can be found in this pdf newsletter
        > (however, the actual article relating to our work is contained on page
        > 20-22 of the magazine).
        > >
        > > http://www.ansyssol
        <http://www.ansyssolutions.com/Solutions%20Fall%2006_LoRes1.pdf>
        utions.com/Solutions%20Fall%2006_LoRes1.pdf
        > >
        > > As far as the "Guide on How to Develop Small Hydropower Plant", I am
        > not familiar with this book or the equations used so cannot comment on
        > that directly. I use/ have used other text books on the topic to
        > assist in the turbine design, these are usually for much larger Kaplan
        > turbines and can be quite theoretical in nature. These however can be
        > adapted for use to the design of smaller machines.
        > >
        > > If there is something more specific you need help with, let me know.
        > Hopefully, all going well, I will be able to make available the final
        > spreadsheet I develop and gather comments back from interested people.
        > >
        > > regards
        > > Robert Simpson
        > >
        > >
        >
        >
        >
        >
        >
        >
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      • acme11_hydro
        Hi Joel Please send me message to mail, if you want that I send some literature to you. We will figure out something perhaps together from this. Regards Marko
        Message 3 of 12 , May 11, 2007
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          Hi Joel

          Please send me message to mail, if you want that I send some
          literature to you. We will figure out something perhaps together from
          this.

          Regards
          Marko



          --- In microhydro@yahoogroups.com, "joel" <wd6fyc@...> wrote:
          >
          > I have been entering the math from "Guide on How to Develop a Small
          > Hydropower Plant" into an Excel spreadsheet. Everything seems to track
          > by the examples at the end of the chapter for the Pelton and Francis
          > dimensions but there is no example problem for a Kaplan's dimensions.
          > What I have noticed is that with inputs above a Kaplan's normal
          > specific speed the hub diameter becomes larger than the blade diameter.
          > Has anyone one else had that problem on do I have a math error.
          >
          > Thanks Joel
          >
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