Max:
One can make, on the fly, a Turgo or Pelton with a defined PCD when you have Buckets that can be bolted to a circular plate, the PCD changes are based on the Bucket size and the mounting RIB to the plate. With a simple mathematical calculation you can increase the PCD, Bucket by Bucket -- having this way a Turbine designed to a specific site head and volume. As well, you can add one, two, three, four nozzles and if required you may use a Nozzle that may cover more than one Bucket at the same time and finally one can make an annulus ring nozzle to cover the whole Turbine Buckets to attain a lot of power. In Michael's client case the water source volume was limited at times, so he had to have different nozzles sizes to harvest the available energy at any specific time -- I would have preferred a Needle Valve Nozzle with an automatic adjustment to maintain the Maximum Power Point Tracking ( MPPT) by just reading the dynamic pressure to control the Needle Valve. Michael makes his Turbine sizes as needed Regards Nando ----- Original Message ----- From: "Max Klohn" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, November 02, 2004 8:40 AM Subject: Re: [microhydro] Abrasion and surface hardness > > > El mar, 02 de 11 de 2004 a las 05:38, Michael Lawley escribi�: > > Hi, > > > > To answer your questions. Below is data relayed to me by the client, I'm not convinced about the accuracy of the data but here it is. > > > > Original unit was running at 131m on the gauge, 24- volt battery system. > > The client has opened up the jet measuring the exhaust water and current flow to the batteries. It seems a bit erratic to me so there is probably some experimental error here. Our agent called in recently and advise that his measurements were at best approximate, but is gives a general picture. > > > > Results below are for a worn bronze Pelton rotor > > 2.5mm jet, 0.25 L/s, 1.5 amps, 36 Watts, 11% > > 2.77mm jet, 0.3 L/s, 4 amps, 96 Watts, 25% > > 3.0mm jet, 0.35 L/s, 7 amps, 210 Watts, 47% > > 3.17mm jet, 0.40 L/s, 11 amps, 264 Watts, 52% > > looks quite good (way too good?) performance for a car alternator. > > why did he use so small nozzles? it seems he has at least 1 l/s > available in his stream > > > > > The only result we got back for our turbine was with 5.1mm jet on the same installation > > delivering 30 amps at 24 volts. > > > > 5.1mm jet, 1 L/s, 30 amps, 720 Watts, 56% > > not bad... some efficiency gain. > > > > > > We find that running a large rotor keeps the rpm down, the losses to air friction and bearings are less at a lower rpm. We still run the Pelton rotor at its optimum rpm and the Smart Drive magnetic rotor can be moved in and out to alter the running speed until you achieve maximum output. > > > My understanding is that (at least for Pelton runners) that there are > optimum nozzle-to-bucket and nozzle-to-p.c.d. (10-11%) relationships > that one should not stray too far. > > Is it the case too for Turgo runners? or is this arrangement more > tolerant? > > > > I cannot agree that there is any rotor efficiency loss, if you run it at its optimum speed (a little under half the theoretical jet velocity) the rotor will maintain efficiency. > > > with 130 m head you have a Vjet around 50 m/s, and if you go with a 1000 > RPM generator you'd need a runner with about 40 cm p.c.d. to match > vjet/2. > > What is the pcd of your turgo runner? > > > Best regards, > > Max > > > Regards > > > > > > > > Michael Lawley > > Renewable Energy Engineer > > EcoInnovation > > 671 Kent Road > > R.D.1 > > New Plymouth > > New Zealand > > > > Phone: (NZ) 06 752 2765 > > Web site: www.ecoinn.co.nz > > email: [EMAIL PROTECTED] > > > > > > ----- Original Message ----- > > From: Max Klohn > > To: [EMAIL PROTECTED] > > Sent: Tuesday, November 02, 2004 2:32 AM > > Subject: Re: [microhydro] Abrasion and surface hardness > > > > > > > > Hi Michael, > > > > a "large", low RPM rotor at such high head and low flow? what is the % > > efficiency penality you get from that choice? > > > > I agree from my own experience that car alternators are quite > > inefficient, so the smartdrive efficiency gain should compensate for the > > rotor efficiency loss. Just for curiosity, how much power was your > > client getting before and now? > > . > > Max > > > > El vie, 29 de 10 de 2004 a las 17:33, Michael Lawley escribi�: > > > By way of example, we recently supplied a turbine on a site with a 135m of head, flow 0.5-1 L/s. > > > > > > The turbine the clients been using for the last 2 years had a bronze Pelton rotor made in the USA using a car alternator. The bronze rotor has been all but worn away after 2 years of continuous use. Also the car alternator needed the brushes replacing every 6 months and overhauling every 12 months. With a small PCD rotor it was running at about 2500 rpm. After 2 years of running the bronze rotor is very badly worn and unusable. > > > > > > We supplied this client a plastic Pelton rotor turbine on a trial basis to see what would happen. The rotor PCD is much larger as it is only running at 1000 rpm on a smart drive PMG. > > > > > > After 50 days on test the client has decided to purchase the turbine, he has indicated that some wear has occurred but is happy with the unit. After talking to the client most of the wear occurred when he was doing high flow tests. We has a 100mm line (way to large for the low flow he has most of the time). When he opened up the line with a larger jet accumulated grit/slit in the line started to move and sand blasted the rotor for may hours (the line is long and it took time to clean out). His view is that most of the wear occurred at this time as up to this point there was no noticeable wear on the spoons. > > > > > > We normally only approve them up to 100m of head. You can see from this example that 135m might be pushing it. Even if the spoons only last 6 months, 4 sets are still only a fraction of the price of the bronze unit. In fact he could buy over 10 sets of replacement spoons for the price of one bronze rotor. If you always have a spare set on hand then it is not a problem. It will not be long before we see Chinese injection moulded Pelton spoons that will make even our ones look expensive. > > > > > > Metal spoons have advantages but the labour component required to polish and balance them means that there are expensive to make in developed countries with high labour rates. Injection moulding on the other hand takes about 10 seconds a shot. > > > > > > For most clients in the 20-70m range (that we commonly supply) we have not had any reports of wear problem and we have enough of them out there to have heard of a problem if it existed. We wouldn't give a 2 year warrantee if we thought they wouldn't do the job. > > > > > > > > > > > > Regards > > > > > > > > > > > > Michael Lawley > > > Renewable Energy Engineer > > > EcoInnovation > > > 671 Kent Road > > > R.D.1 > > > New Plymouth > > > New Zealand > > > > > > Phone: (NZ) 06 752 2765 > > > Web site: www.ecoinn.co.nz > > > email: [EMAIL PROTECTED] > > > > > > > > > ----- Original Message ----- > > > From: Marc de Piolenc > > > To: [EMAIL PROTECTED] > > > Sent: Friday, October 29, 2004 1:52 PM > > > Subject: [microhydro] Abrasion and surface hardness > > > > > > > > > > > > I'm a little disturbed at the assumption, evident in > > > many recent messages, that a hard surface is > > > necessarily more resistant to abrasion than a soft > > > one. This is not correct, and people on this list in > > > particular need to be aware of that. > > > > > > When a hard abrasive particle hits a hard surface, it > > > loses nearly none of its kinetic energy, and in a > > > turbulent stream may strike the surface again and > > > again, each time spalling or scraping off a small > > > amount of material. > > > > > > When it hits a soft surface, it tends to lose energy - > > > essentially embedding itself temporarily. This can > > > often result in LESS wear on a soft surface than on a > > > hard one. The ultimate useful application of this > > > property is in an industrial process called lapping, > > > in which a soft tool (the lap) charged with an > > > abrasive, is used to remove material from a much > > > harder workpiece. > > > > > > It is therefore incorrect to assume that a plastic > > > turbine bucket will necessarily have less wear in it > > > than a metal bucket of the same profile. It MAY be so > > > - not all soft surfaces have the property of resisting > > > wear - but that must be substantiated by test. Surface > > > hardness is only one of the relevant parameters. > > > > > > Best, > > > Marc de Piolenc > > > Iligan City, Philippines > > > > > > > > > > > > __________________________________ > > > Do you Yahoo!? > > > Yahoo! Mail Address AutoComplete - You start. We finish. > > > http://promotions.yahoo.com/new_mail > > > > > > > > > > > > > > > > > > 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. 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