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 firstname.lastname@example.org, "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:email@example.com]On Behalf Of acme11_hydro
> -----Original Message-----
> From: firstname.lastname@example.org
> Sent: 27 April 2007 00:09Plant Math question?
> To: email@example.com
> 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
> This email is intended solely for the addressee. It may contain
addressee, please take no action based on it nor show a copy to
anyone. In this case, please reply to this email to highlight the
error. Opinions and information in this email that do not relate to
the official business of Nottingham Trent University shall be
understood as neither given nor endorsed by the University.
> Nottingham Trent University has taken steps to ensure that thisemail and any attachments are virus-free, but we do advise that the
recipient should check that the email and its attachments are actually
virus free. This is in keeping with good computing practice.
> [Non-text portions of this message have been removed]
- 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 firstname.lastname@example.org, "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