Re: Guide on How to Develop a Small Hydropower Plant Math question?
- 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
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.
"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.
- 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 email@example.com, "Simpson, Robert"
>would probably be too high for direct drive to an induction motor as
> Hi Marko,
> For the head and flow rate you mention, the turbine specific speed
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).
>textbooks, such as Nechleba or a couple of other ones written in
> As far as literature goes, most of the ones I use are older
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
>[mailto:firstname.lastname@example.org]On Behalf Of acme11_hydro
> -----Original Message-----
> From: email@example.com
> Sent: 27 April 2007 00:09Plant Math question?
> To: firstname.lastname@example.org
> Subject: [microhydro] Re: Guide on How to Develop a Small Hydropower
> 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
> 3.hub diameterups.com, "Simpson, Robert"
> 4.guide vanes angle
> Can you tell me, which software or literature can be used for this job?
> --- In microhydro@yahoogro <mailto:microhydro%40yahoogroups.com>
> <robert.simpson@> wrote:<http://www.ansyssolutions.com/Solutions%20Fall%2006_LoRes1.pdf>
> > 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
> >private and confidential information. If you are not the intended
> > 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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- 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
--- In email@example.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