Wayne: The velocity of a flowing water is determined by the head ( the difference between to heights when the water is piped between both points).
The water velocity = meter/sec= squreroot( 2 * Head(meter)*9.81(gravity)) GROSS WATTS = Volume(liter/sec) * Head(meter) * 9.81(gravity) Then you need to multiply by the efficiencies of the turbine and the generator to reach the final output power that for small hydros, it looks around 0.6 to 0.7 total efficiency multiplying factor. Regards Nando ----- Original Message ----- From: "wayne burton" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Sunday, October 16, 2005 3:25 PM Subject: Re: [microhydro] Re: direct drive of centrifugal pump by a turbine > > Hello ! > Does anyone know how to increase the velocity/force of > flowing water without using a pump ? > I need to create sufficient force to turn a turbine ? > I know without saying what kind of turbine it might be > a bit hard to give the best solution I just need a > general solution any available theory application > --- Joseph Hartvigsen <[EMAIL PROTECTED]> wrote: > >> Nandi, >> I've recently built a turbine and helped a fellow >> select a pump for >> direct drive from the turbine. I haven't heard yet >> how it worked. In >> principle there are a couple of issues to consider. >> First, a >> centrifugal pump, unlike most generators, has a >> specified direction of >> rotation. With a Pelton, there is no issue as it is >> symmetric and can >> be flipped over to change the direction of rotation. >> A turgo on the >> other hand can also be turned over, but it changes >> the jet entrance >> and exit faces. In the case of the turbine I just >> built for this >> application this meant that the jet exit needed to >> be on the pump >> side. Normally I would prefer the other way so that >> it is easier to >> keep water off the pump bearings. A Pelton will >> deflect water toward >> the pump bearings no mater which direction of >> rotation is required. >> >> The other factor is matching the torque vs. rpm >> curves of the pump and >> turbine. With a pump, the torque increases with rpm. >> With a turbine, >> the torque is highest at 0 rpm and decreases to 0 >> torque at freewheel >> rpm. Somewhere in the middle the two curves >> intersect. That will be >> the operating point. You need to match the turbine >> to the pump so that >> that point of intersection is also at the peak power >> rpm of the >> turbine. This rpm should also be a point compatible >> with matching the >> pump's output head and flow to that required by your >> application. >> >> The torque/power vs. rpm for the turbine can be >> computed with a >> momentum balance. I have such a spreadsheet for any >> impulse turbine on >> my web site. Unfortunately, it is setup only for >> units of hp, ft-lb, etc. >> See http://h-hydro.com/turgo_drive.html near the >> bottom of the page >> >> Most pumps are designed to be driven by an electric >> motor at 3600 or >> 1800 rpm (assuming 60Hz, or 3000/1500 rpm at 50 Hz). >> You should be >> able to obtain a pump curve from the manufacturer. >> These pump curves >> will likely be at 3600 or 1800 rpm. To scale to a >> different rpm, what >> is knows as "turbomachinery affinity laws" are used. >> These laws help >> scale a geometrically similar design to a larger or >> smaller size, or >> scale the performance of a fixed unique device as >> head, flow, rpm, >> power, etc. need to be changed. In the recent case I >> helped with, he >> was eventually able to find a 1200 rpm pump that >> matched his needs, >> but it was a custom industrial pump. >> >> This link has some info, but you can google >> "turbomachinery affinity >> laws" and find dozens of referrences. >> > http://caltechbook.library.caltech.edu/22/01/chap1.htm >> For the same pump run under different conditions "D" >> or the >> characteristic diameter (usually the impeller or >> runner diameter) is >> fixed, and flow varies with rpm (double rpm doubles >> flow capacity), >> Head varies with rpm^2 (double rpm = 4x head) and >> the same for torque. >> Power varies as rpm^3. So if you have a pump rated >> at 1800 rpm and run >> it at 1400 rpm, its flow is reduced to 78%, head & >> torque to 60% of >> the 1800 rpm value, and power is reduced to 47% of >> the rated power. >> >> >> Joe >> >> >> --- In [email protected], "S.N.Group of >> Companies" >> <[EMAIL PROTECTED]> wrote: >> > >> > hi all!!!! >> > >> > >> > has any bodythought of using turbines to drive >> centrifugal pumps >> > directly?? >> > we are currently working on a concept wherein the >> turbine shft will be >> > directly connected to the drive shaft of a >> centrifugal pump . providing >> > flow all year round . >> > any help in this matter is solicited. >> > >> > regards, >> > nandi >> > >> >> >> >> >> >> > > > > > __________________________________ > Yahoo! Music Unlimited > Access over 1 million songs. Try it free. > http://music.yahoo.com/unlimited/ > > > > > > Does your company feature in the microhydro business directory at > http://microhydropower.net/directory ? 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