Brian, I routinely give this homework problem to my renewable energy students. A man I know seriously suggested it for energy generation.
Assume that the annual rainfall all hits the roof of a house in one rain! The water is directed through gutters to one descending pipe to a microturbine. Assume annual rainfall is 48 inches, and the house roof is 24 by 36 feet. Compute the quantity of water falling on the roof, assume it runs out continuously through the turbine in one minute, the head is 8 feet, and find the horsepower of the turbine. (One could collect all rain for a year, and then "flush" it through the turbine all at once.) HP input from water = WQH/33000, where W is 62.42 pounds per cubic foot, Q is flow in cubic feet per minute, and H is the head in feet (1hp=33000ft-lbs/minute) The volume is 4 ft x 24 ft x 36 ft = 3456 cubic feet. The hp is then 62.42 pounds per cubic foot x 3456/cubic feet per minute x 8 ft/33000 = ~0.015 hp. Multiply by 746 watts per hp to get 11.28 watts! The energy is power x time, so 11.28 watts x 1/60 hour = 0.18 watt-hours input. The turbine has additional losses, as does the generator. BTW, a 12Vdc bilge pump draws about 2A, so is ~24 watts. Imagine said pump pushing water to 8 ft overhead to roof level. Then, let the water flow back down from a tank through a microturbine and generator. Can the microturbine make 24 watts? Why? Frank |=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= | Frank R. Leslie, M.S. Space Tech | Adjunct Lecturer in Renewable Energy | Florida Tech, DMES, Rm. 104, 150 W. University Blvd., Melbourne FL 32901 | (321) 674-7377 | http://my.fit.edu/~fleslie (Renewable Energy) | Florida Tech email: [EMAIL PROTECTED] | http://my.fit.edu/wx_fit/roberts/RH.htm | Adjunct Advisor to the Green Campus Group (Campus Sustainability) | Home: 1017 Glenham Drive, NE, Palm Bay FL 32905-4855 | (321) 768-6629 | Home email: [EMAIL PROTECTED] | 28-01.3130N / 80-35.6136W | www.geocities.com/windy4us (Wind Energy Experimenters) | KD4EYQ 050912 |=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] Behalf Of wayne burton Sent: Thursday, October 13, 2005 7:40 AM To: [email protected] Subject: Re: [microhydro] Rams NOT most reliable pumps in world, Not cheapest to operate either! hello I am a final year engineering student and I would like to investigate/explore the possibility of using water run-off from a roof or roofs to run a microhydro plant.Do you have any ideas regarding what kind of turbine or system set-up would be necessary. any help would be appreciated. --- Brian White <[EMAIL PROTECTED]> wrote: > I would argue that the pulser pump > http://members.tripod.com/~nxtwave/gaiatech/pulser/index.htm > and > http://www.animatedsoftware.com./elearning/All%20About%20Pumps/ > glossary/aap_glossary.html > is more reliable and cheaper to operate. > It has no moving parts and I bet you could make one > from bamboo or > hollow wood if you wanted. > (I am not pretending that it is as energy efficient > as a ram). > BUT there are lots of situations round the world > where 5 to 500 liters > of water falls a couple of feet and people want to > pump water 10 or > 20 feet higher. In such a situation, the capital > cost of a pulser pump > might be lower than the capital cost of a ram (and I > dont think a ram > can manage a 2 ft fall anyway). > Brian White > > > > > > > __________________________________ 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 ? 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. The microhydro-group does not endorse products or support the advertisements in any way. More information on micro hydropower at http://microhydropower.net To unsubscribe: send empty message to [EMAIL PROTECTED] SPONSORED LINKS Energy management Energy gels Energy conservation home Energy savings Energy Energy audit YAHOO! 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