deguzman - direct conversion cycles (hydro power)

8/9/2019 DEGUZMAN - Direct Conversion Cycles (Hydro Power)

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*hydro power*hydro power

HYDRO water

power from water

most widely used renewable source of energyhydroelectricity power generated by capturing

energy from water

hydro energy is available aspotential energyand as kinetic energy

harnessing this energy involve water flowthrough a turbine


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B.C : ~2000 yrs. ago, Greeks used waterwheels to grind wheat to flour

1700s : evolution of modern hydro powerturbine

: Bernard Forest de Belidor, Frenchhydraulic and military engineer describedusing a machine with a vertical axisinstead of a horizontal one

: hydro power was used mostly forpumping irrigation and milling lumber


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1880 : dynamo belted to a water turbine at theWolverine Chair Factorywas first used topower 16 lamps

1882 : opening of the first operationalhydroelectric generating station in theUnited States in Appleton, Wisconsin

producing 12.5kWof power

1900s : 40% of the electricity consumed in theU.S. was provided by hydroelectric power


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1950 : the largest dam built by the U.S. Bureauof Reclamation was the Roosevelt Dam inArizona

: its power output increased from4500kWto 36000kW

in20yrs. : around 300 hydroelectric plants becameoperational around the world


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TODAY

the size of hydro power plants rangesfrom several hundred kilowatts to

several hundred megawatts they have combined capacity of675000MWand produce over 2.3 trillionkWh of electricity worldwide (equivalent

to 3.6 billion barrels of oil) about 20% of the worlds power come

from hydroelectric power (REN21sRenewables Status Report)


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Two conditions required to generate hydroelectricpower:

1. source of flowing water

2. topographic reliefin the landscape


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Typical components:

1. dam

most important component

thicker at the bottom

2. reservoir

place behind the dam where water is stored

3. control gates (intake gates)

control the release of water


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4. penstocks (pipes)

carry the water from the reservoir to theturbines

5. powerhouse (power generation unit) contains the turbines and the generator

6. electrical substation

where the electricity produced by therotation of the turbine shaft is transmitted

here transformers increase the voltages toallow transmission


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the water in the reservoir is at a height above therest of the dam structure

the water in the penstocks possess both KE and PE

it is the turbine which converts the energy of water

into rotational motion of the shaft


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IMPOUNDMENT

is by far the most common type

makes use of a dam

typically a large hydro power system

turbines used are usually reaction turbines whoseblades are submerged fully in water

available energy depends on the head of the waterand on the volume of the waterflowing throughthe turbine


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The potential energy per unit volume:

PE/V = ghwhere:

- density of water (103 kg/m3)

h - height in meters (m)

g - acceleration due to gravity (9.81 m/s2)

The power generated in the impounded case:

P = tghQwhere:

Q - volume flow rate (m3/s)

t- efficiency of the turbine

IMPOUNDMENT


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DIVERSION(run of river)

channels a portion of a fast flowing river

impulse turbines (partially submerged) are used infast-flowing run of river installations

Kaplan turbines (submerged) are used for deeper,slower-flowing rivers

available energy depends on the velocity of thewaterand on the volume of the waterflowingthrough the turbine


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The kinetic energy per unit volume:

KE/V = v2where:

- density of water (103 kg/m3)

v velocity of the water (m/s)

The power generated in run of river installments:

P = tv2Qwhere:

Q - volume flow rate (m3/s)

t

- efficiency of the turbine

DIVERSION


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PUMPEDSTORAGE

reuses water

water is pumped back to the upper reservoir atnon-peak times

water is released back to the lower reservoir togenerate electricity during periods of high demand


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LARGE produce up to 30MW of power

SMALL / MINI produce 100kW~30MW of power

efficiencies of about 65%

AC-Direct

MICRO produce up to 100kW of powerefficiencies of about 50%

AC is converted to DC for storage


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clean source of energy

inexpensive electricity and produce no pollution

only cost is capital cost

expensive installationsuitable site is difficult to find

destruction of surrounding (i.e. flooding)


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Ideally, water quality should be retained but thisis not the case in real applications.

Water often takes on a higher temperature, losesoxygen content, and gains phosphorus and

nitrogen content.


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Increasing the head difference and/or volume flowthrough the penstock increases the power delivered

by the plant.

Pimpounded = tghQ

Pdiversion = tv2Q

Other improvements may include reduction of possibleenvironment degradation and enhancing water

quality.

The new turbines designed were based on a redesign ofa pump impeller.


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~ Yangtze River in Sandouping, Yinchang, Hubei,China

~ capacity of 22500MWwhen completed

~ capacity of17600MWat present

~ planned to be completed in the year 2011

~ bottom side is 115m thick; top side is 40m thick

~ total length is 660km~ width is 1.12km


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~ there are over 420principal rivers andwatershed areas of about 25000km2

~ hydro power generation started in the 1900s in

the Northern mountains of Luzon

~ currently, there are 134 hydro power plants inoperation (27large, 52 mini-hydro, 61 micro-

hydro)~ in 2013: capacity from 2518MW to 5468MW


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Pump Storage

A power grid has a load pattern during one 24-hour period thataverages 600 MW during 18 hours and 1200 MW during 6hours. A pumped-hydro energy storage system with anelevation of 100 ft is considered.

Calculate: the power output of a power plant (in MW) thatwould meet the load demand with and without storage

Solution:Turnaround efficiency is assumed to be 65% (El-Wakil, Power Plant

Technology, p.680)

~ with storage:


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Part of the energy produced during non-peak hours when P is above

600 MW will be stored and will be released during peak hours when

energy is required to meet the 1200 MW demand.

0.65*(P 600)*18 = (1200 P)*6

P is the required power output.


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P is therefore:

P = 803.39 MW ANS.

~without storage:

Without anywhere to store the excess energy during peak

hours, the plant shout meet the average demand during peak

hours.

Therefore:

P = 1200.00 MW ANS.


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El-Wakil, M. M. Powerplant Technology. McGraw-Hill Book Company,

1984.Daughtry, Robert L. Fluid Mechanics with Engineering Applications. SI

Metric Edition. Singapore: McGraw-Hill Book Company, 1989.

Energy Sources: Hydroelectric Power.http://home.clara.net/darvill/altenerg/hydro.htm

Saburnido, R. Renewable Energy in the Philippines. 2009 March 1.http://www.bukisa.com/articles/38626_renewable-energy-in-the-philippines

Farret, F.A. Integration of Alternative Sources of Energy. Hoboken, NewJersey. John Wiley&Sons, Inc.

Newman, David. History of Hydroelectric Power.http://ffden2.phys.uaf.edu/104_spring2004.web.dir/Todd_Robyn/Page5.htm

Electropaedia. http://www.mpoweruk.com/hydro_power.htm

Chima, R.V. NASA Glenn Research Center: CFD Codes for Turbomachinery.Ohio, U.S.A. http://www.grc.nasa.gov/WWW/5810/rvc/swift.htm

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