Hi,
That's 57% conversion efficiency, this is about 5% higher than the published power curve. With the leaf cutter we removed the blade and machined if so that it if flat on the top, it was close to flat to start with. I then positioned a piece on 20mmx20mm s/s square bar in through one of the guide vanes and bolted in into position a fraction of a mm about the top the blades. Any leaf that wraps around the blade is cut off, also small twigs get mulched pretty quickly. This unit is the 1000W unit running at 600 rpm. It has plenty of torque to mulch up fairly large twigs. We have also found that ensuring the water entering the unit if as turbulent as possible helps as you suggested. All these type of units get bunged up in floods. We have 3m floods on this site and are only operating at 1.8m head. The generator is the only visible sign above the water line during floods. After floods the silt fills the unit but on cleaning the intake screen and getting it flowing it's amazing how much silt 140 l/s can move in just a few minutes, so unit tends to clean itself. PowperPal claim a 50% efficiency. We never go that with their unmodified unit but have obtained at the turbine over 1.2 kw on 1.8m head. As we have a 500m cable and 3 transformer we are only delivering 850-950 Watts (depends on how much water is available). Its difficult to measure 140l/s accurately at the site. Assuming this is correct (never assume anything) then this is a conversion efficiency around the 50% mark, similar to what you are obtaining In contrast we have a 500W water wheel here on 3m head. It never needs cleaning but can only handle 1.4m of flood water. Regards Michael Lawley Renewable Energy Engineer EcoInnovation 671 Kent Road R.D.1 New Plymouth New Zealand Phone: (NZ) 06 752 2765 Fax: (NZ) 06 7522768 Web site: www.ecoinn.co.nz email: [EMAIL PROTECTED] ----- Original Message ----- From: Jeffe & Carrie Aronson To: [EMAIL PROTECTED] Sent: Sunday, November 28, 2004 8:57 PM Subject: Re: [microhydro] Abrasion and surface hardness Hey Michael: Getting 500 watts at the machine from a 70 inch head at present. 50 ltrs/sec says Paul...easy to clean, just close the butterfly until the unit is sucking air with the water and the turbulance shears away the tiny leaves and moss that affects it and that's about all that can get into the small vane entry. Should get 1 kw from 2 units using 100 ltrs.sec....which gives us a small amount of leeway at low water. Can you send a drawing or foto of your leaf cutter idea?? I'm thinking of a "pyramid" shaped coanda within the open box holding the turbine...(see attachment I sent just a while ago) and wondering how that'll work. As we don't have any other outflow besides the turbine itself...but now can allow some water to flow over the top edge of one side of the box, this, or something similar might be the answer... Jeffe On 11/18/04 7:26 AM, "Michael Lawley" <[EMAIL PROTECTED]> wrote: > > > Hi Jeffe, > > Unlikely to be in the area but would be keen to read the results you are > obtaining and your conversion efficiency. I have the data for your old turbine > that you emailed me and it would be interesting to see the improvement that > has been obtained from changing to the ES LH1000. I thought you had only about > 2m of head so one of these units might not get you the 1000 Watts you could > get. Would be interested to read how this has worked out for you. > > We installed a 1000 W LH PowerPal about 15 months ago and it was plagued with > overheating and poor performance problems and we cooked the generator at well > below the 1000W rating. We then installed a Smart Drive on the body of a > PowerPal unit and have had it operating at over 1000 W on a 1.8m head at about > 140 l/s. We never managed to get more than about 700W from the original > PowerPal unit. On low head sites most money goes into the site works. The > turbine cost is low relatively (you just need to find one that works). I'm > surprised you didn't change the original unit over years ago. > > We have been working on our own low head version in NZ., but are looking at > 500 Watts at 1.5m as the target market. You'd install 2 units for 1000 Watt > output. > > Have you sorted our issues like leaves blocking the intake. On the PowerPal > leaves would wrap around the leading edge of the prop. In the end I removed > the prop and machined a flat on top and placed a cutter just above the > blades, it works a treat and cuts any leaves that manage to get through. It > only need manual cleanly after floods which tends to be about 1-2 a month, so > the client can live with this. > > > 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: Jeffe & Carrie Aronson > To: [EMAIL PROTECTED] > Sent: Wednesday, November 17, 2004 5:42 PM > Subject: Re: [microhydro] Abrasion and surface hardness > > > > Hey Michael...we just installed a new Energy Systems low head hydro here in > Victoria in case you are in the area ever and want to see it in > action...loving it! > > Jeffe > > On 11/2/04 6:38 PM, "Michael Lawley" <[EMAIL PROTECTED]> wrote: > >> >> >> 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% >> >> 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% >> >> >> 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. >> >> 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. >> >> 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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