Electrical Energy Electricity. Potential Energy. Kinetic Energy. Mechanical Energy

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2 Potential Energy Electrical Energy Electricity Kinetic Energy Mechanical Energy 2

3 Nuclear 2% Hydro 33% Fossil Fuel 65%

4 Four major power producers in the country WAPDA (Water & Power Development Authority) KESC (Karachi Electric Supply Company) IPPs (Independent Power Producers) PAEC (Pakistan Atomic Energy Commission).

5 Power Status Existing Generation Proposed/Committed d Total Existing/Committed itt Expected Available Demand (summer peak)

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7 Hydropower, along with biomass, is an important renewable energy source. The current mix of world energy supply is mainly based on oil, coal, natural gas, and - to a lesser extent - on hydropower and nuclear energy. Until 2020 natural gas will even grow in Until 2020 natural gas will even grow in importance

8 Beyond 2020, however, due to depletion of cheap and near-demand gas reserves, due to political reasons and due to environmental reasons new technologies and increased use of renewable energy must be put in place. Massive investment in energy infrastructure will be needed (Organisation for Economic Cooperation and Development-OECD 2002)

9 In developing countries hydropower is expected to be the fastest-growing renewable energy source (OECD, 2002). Hydropower is based on the kinetic energy of rivers using turbines. Hydroelectric projects can include dams, reservoirs, stream diversion structures, powerhouses containing turbines, and transmission i lines. Reservoirs behind dams often provide other benefits, p, e.g. recreation, flood control and navigation, irrigation, and municipal water supply

10 According to the World Commission on Dams (WCD) the world s more than 45,000 large dams have played an important role in harnessing water resources for food production (irrigation), power generation, flood control and domestic water use. On a global scale hydropower has a share of 19% in electricity generation. Also, 30-40% of irrigated land relies on dams, and 800 million people benefit from food produced by dam related irrigation

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12 Abundant and reliable source of clean and renewable energy. Comparatively inexpensive renewable energy source with low levels of greenhouse gas (GHG) emissions It can play a key role in addressing climate change, particularly in countries with a substantial ti undeveloped d hydropower potential

13 Although there are hydroelectric projects under construction in about 80 countries, most of the remaining hydropower potential in the world may be found in developing countries, particularly in South and Central Asia, Latin America, Turkey, Africa, and Russia Also there is a large potential in operational improvement and rehabilitation of hydropower plants

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15 Runoff river development Diversion and canal development Storage regulation developments Pumped/storage developments Tidal power developments Single purpose developments Multipurpose developments Base load developments Peak load developments

16 Hydropower development has a significant role to play in the future energy production of most countries of the world, because rising costs of alternative energy sources are making small-scale scale hydropower developments economically competitive and because hydropower plants are well suited to provide making power.

17 Identify a hydropower development in your area.present its physical characteristics i in order to determine its type. Develop a list of sources for finding information on hydropower production, its relative importance in energy production and projections for future developments.

18 In order to understand the fundamentals of hydropower development, it is important to have a knowledge of the important terminologies of the field. Work is transferred energy and is the product of force times the distance moved.

19 Energy is the capacity to do work. Water, by its very nature of being a fluid that moves easily by action of gravity, has energy. The work done by water in producing electrical energy is usually measured in kilowatt-hours (kwh). The energyfrom water can be either ih potential energy by virtue of position, pressure energy due to the water pressure, or kinetic energy by virtue of the water's moving force or action.

20 Power is the rate of transferring energy or work per unit of time. If a mass m is raised through height H, it gains energy mgh. If it does so in time t then the rate of conversion is mgh/t For a fluid in motion, the mass flow rate is m/t or ρq. The rate of conversion to or from fluid energy when the total head is changed by H is therefore ρq(gh) or power = ρgqh In hydropower kilowatts (kw). language it is measured in Power capacity is often used in referring to the rated capability of the hydro plant to produce energy.

21 Manufacturers of hydraulic turbines are usually required to specify what the rated capacity of their units is in kilowatts. Two words frequently used in hydroelectric terminology are demand and load. Demand refers to the amount of power needed or desired while load refers to the rate at which electrical energy is actually delivered to or by a system. Load can include the output from several hydropower plants.

22 The power capacity of a hydropower plant is primarily a function of two main variables of the water which are water discharge and hydraulic head. Water discharge is the volume rate of flow with respect to time through the plant. FuII gate discharge is the flow condition which prevails when turbine gates or valves are fully open

23 Pumps and turbines are energy conversion devices Turbines turn fluid energy into electrical or mechanical energy Pumps convert electrical or mechanical energy into fluid energy Energy per unit weight is head H The first two terms represent the piezometric head hil th l t t t d i h d while the last term represents dynamic head.

24 Hydraulic head is the elevation difference the water falls in passing through the plant. Gross head of ahydropowerfacility is the difference between headwater elevation and tailwater elevation Net head is the effective head on the turbine and is equal to the gross head minus the hydraulic losses before entrance to the turbine and outlet losses Design head is the effective head for which the Design head is the effective head for which the turbine is designed for best speed and efficiency.

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26 Rotating machine that adds or extracts energy from a fluid by virtue of a rotating system of blades Hydraulic machines can be divided into displacement machines and rotodynamic machines In displacement machines the volume of a chamber is increased/decreased by forcing a fluid into and out of the chamber. e.g. tyre pump, human heart etc.

27 Rotodynamic machines have a set of blades, buckets, flow channels/ passages forming a rotor. Its rotation produces dynamic effects to extract/add t/ energy from/to a fluid. Includes turbines and pumps Have rotating element through which the fluid passes Th i ll d i bi d i ll The rotor is called a runner in turbine and impeller in the pump.

28 Turbine is a device that extracts energy from a fluid (converts the energy held by the fluid to mechanical energy) Pumps are devices that add energy to the fluid (e.g. pumps, fans, blowers and compressors).

29 Hydro electric power is the most remarkable development pertaining to the exploitation of water resources throughout the world Hydroelectric power is developed by hydraulic turbines which are hydraulic machines. Turbines convert hydraulic energy or hydro- potential ti into mechanical energy. Mechanical energy developed by turbines is Mechanical energy developed by turbines is used to run electric generators coupled to the shaft of turbines

30 J.V. Poncelet first introduced the idea of the development of mechanical energy through hydraulic energy Modern hydraulic turbines have been developed by L.A. Pelton (impulse), G. Coriolis and J.B.Francis (reaction) and V Kaplan (propeller)

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32 hydraulic efficiency Runner output/actual power supplied to runner; =runner output/(ρgqh) mechanical efficiency Shaft output/runner output volumetric efficiency vol. of water actually striking runner/vol. of water supplied to the turbine (Q/(Q+ΔQ)) overall efficiency shaft output/net power available= product of all of above efficiencies

33 On the basis of hydraulic action or type of energy at the inlet Impulse Turbine (pelton wheel) Reaction Turbine (francis turbine) On the basis of direction of flow through the runner Tangential flow turbine (pelton) Radial flow turbine (francis ) Axial Flow Turbine (Kaplan) Mixed flow turbine (modern francis)

34 On the basis of head of water High head turbine (pelton, H>250m) Medium head turbine (modern francis, m) Low head turbine (kaplan, <60m) On the basis of specific speed Ns of the turbine Low specific speed (pelton, 10-35) Medium (francis, ) High specific speed (kaplan, ) Specific speed is the speed of turbine for producing unit power under unit head

35 Most commonly used impulse or tangential flow turbine Named after its pioneer Leston A Pelton ( ). 1908) Suitable to be used for high head hydroelectric power plants

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37 Runner is acircular disc with anumber of evenly spaced vanes or buckets semi- ellipsoidal in shape Each bucket is divided into two symmetrical compartments by a sharp edge ridge called splitter Jet of water normally impinges on the splitter dividing into two parts and leaving at the outer edge

38 To get the full reaction of the jet, it has to be turned through 180 degree but it may strike the incoming bucket thus retarding its speed The angle through which the jet is turned is The angle through which the jet is turned is normally kept between 160 and 170.

39 Due to the spherical surface of the buckets, the outlet angle is different for all points on the outer edge As the splitter takes the full impact of the jet, so it has to be quite strong and should not be having asharp edge The angle at the centre of the bucket is The angle at the centre of the bucket is normally taken as 5-8 degrees.

40 To avoid erosion of buckets due to impurities present in water, cast iron buckets are used for low head plants while cast steel, stainless steel and bronze are used for medium head plants Buckets are either cast as an integral part or are bolted to the rim.

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42 Function is to convert pressure energy to highh velocity energy in the form of jet. A spear is provided in the nozzle to control the flow due to varying load on the turbine. Nozzle is made of either cast iron or cast steel Nozzle mouth ring and spear tip are made of nong p p abrasive material (stainless steel or bronze) and can easily be replaced

43 It does not have any hydraulic function Provided to avoid accidents, splashing of water and to lead the water to the tail race. Made in two parts to facilitate assembling Material used is usually cast iron.

44 Width B of the bucket is normally taken as 4 to 5 d. The depth of the bucket (c) normally lies between 0.81 to 1.05d. Length L of the bucket is 2.4 to 3.2d Other dimensions are M = 1.11 to 1.25d l = 1.2 to 1.9d ɸ = 10 to 15 degrees β1 = 5-8 degrees

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46 The number of buckets is decided d such that the frictional loss is minimum and the path of the jet is notdisturbed. d Also the jet must be fully utilised Taygun gave the following relation for the calculation of number of buckets. b n = 1 D D + 15 = d d + 15

47 At the inlet V V V α r f = Vw = = 0 V At the outlet u = 0 ; θ = 0 u = 1 u

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49 Assuming a smooth flow on the bucket, no loss occurs V r 1 = V r ( ) u Vw 1 = Vr1 cosφ u1 = Vr cosφ u = V u cosφ The force exerted by jet in the direction of motion x [ V ( V )] = av ( V V ) F = ρav ρ + w w1 w w1

50 Work done by the jet on the runner F u = ρav ( V + V )u x w w1 Power obtained by runner ρav ( V + V ) w w u kw Work done per unit weight of water ρav ( V + V ) w ρgavv w 1 u 1 = g ( V + V )u w w1

51 Hydraulic Efficiencyi η h = Substituting ( V + V ) u 2 ( V + V ) ρav w w1 2 w + = 1 3 ρav V 2 2 w1 u V V and ( ) w = V w 1 = V u cosφ u [ V + ( V u) cosφ u] u 2[ ( V u) + ( V u) cosφ] 2 η h = 2 V 2( V u)( 1+ cosφ ) u = 2 V = V 2 u

52 For maximum efficiency i d h η du = 0 ( 1+ cos φ ) d ( 2 2Vu 2u ) = 0 2 V du 2V 4u = 0 u = V / 2 Putting in eq for maximum efficiency

53 η h = ( 1+ cosφ ) 2

54 If a turbine is working under a net head H, then the ideal velocity of the wheel is given by 2gH But due to the frictional loss, the actual velocity is slightly less than this, so the velocity V of jet at inlet V = Cv 2gH Cv (coefficient of velocity ranges from 0.97 to 0.99

55 Although, theoretically, u = V / 2 But actually, occurs when u= 0.46V η h max If u is expressed in terms of speed ratio (ratio of tangential velocity of wheel to theoretical velocity of jet) u K u 2gH = u = gh Ku ranges from 0.43 to 0.47

56 The angle through which the jet is deflected is taken as 165 degree and ɸ at the outlet velocity triangle is 15 degrees. Least diameter of the jet is given by Q d d = 2 π 4 4Q 2 = av = d C v 2 gh = = π C v 2 g H 1 / 4 1 / 2 Q ( ) π 0.98 Q H 2 1 / 2 g H 2

57 If D is the mean diameter of the wheel and N is the rotation of the wheel in rpm u D = = πdn 60 60u 60. K = πnn πnn u 2 gh

58 Ratio of diameter of the runner to the least diameter of the jet is known as jet ratio D/d D/d is taken between 11 to 14 for maximum efficiency Normal value is taken as 12 if not given

59 It is also called pressure turbine Water enters the turbine under pressure after passing through the guide vanes Most common types are Francis (James B Francis) American Engineer ( ) and Kaplan (V.Kaplan) Austrian engineer ( )

60 Penstock Casing Guide Wheel and Guide Vanes or blades Runner and runner vanes Draft tube

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63 It is a large size conduit that conveys water from the upstream of the dam/reservoir to the turbine runner

64 Spiral in shape through which water from penstock enters the turbine Cross section gradually decreases to maintain velocity and pressure U ll d f t l t d i t Usually made of steel or concrete and is water tight

65 Guide wheel is stationary and circular in shape Fitted with guide blades to guide water into runner vanes G id bl d h l i h k l t iki f Guide blades help in shock less striking of water on runner blades

66 Runner is a circular wheel having radial vanes (radial curved) installed on it Runner vanes have a smooth surface and are shaped to ensure that water enters and leaves without shock Made of iron or stainless steel and are keyed to the shaft

67 Water flows from the runner to the tail race through a tube called draft tube Usually diverging in cross section and is fully airtight Takes water from the runner to the tail race

68 Draft tubes are normally of three types. Moody spreading tube Simple Elbow Elbow type with circular inlet and rectangular outlet Divergent type The most common type is the straight divergent type. The cone angle should not be more than 8 degrees otherwise it will lead to the formation of eddies.

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71 Guide vanes guide the water to enter the runner vanes Water flows in an inward radial direction and discharges from the pitch diameter of the runner (D 1 -inner diameter)

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73 Work done (by jet on moving curved vane) ρ ( V u ± V u ) av ± w = ρ Q V w1 1 ( V u ± V u ) w ± w 1u 1 also πdn u = 60 π D N 1 u 1 = 60

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75 Work done per unit weight per unit time 1 ( V u V u ) g < 90 ± β o w w1 1 +ve sign β > 90 o -ve sign β = w 90 o, V 1 = 0

76 Work done V w gu Hydraulic efficiency η h = [ V u ± V ] ρav w 1/ 2( ρav w 3 1u 1 ) β = w 90 o, V = 1 0 η h =?

77 Speed Ratio Ku u = 0.6 to 0.9 2gH Flow ratio V f 2 gh 0.15 to 0.30

78 Discharge equation Q = π DBV = πd B V f 1 1 f B and B 1 are the widths of runner at inlet and outlet If t is the thickness of the vanes and there are n number of vanes then Q ( D nt) BV f = π f

79 If p is the pressure at inlet then H 2 p V = + ρgρ g 2 g For radial flow at outlet o V β = 90, V = 0 w1

80 For radial flow at inlet α = 90 o, V = w 0

81 Quite similar il to the inward flow reaction turbine Moving vanes surround guide vanes and water from casing flows in the outward direction from guide vanes Inlet is at inner diameter da D of the runner and and outlet is at outer diameter D 1 so u<u 1

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83 As the discharge at the outlet is radial so V = 0 w1 Work done per unit time will then be ρ Q ( V u ) ρq w Work done per unit weight 1 ( V u ) g w

84 Hydraulic efficiency η h = V w gh u Ratio of width of wheel to its diameter B 0.1 to 0.4 D

85 Flow ratio V f 2 gh 015t 0.15 to 0.30 Speed ratio u 2gH 06to

86 An inward flow reaction turbine has external and internal diameters as 1.2m and 0.6m respectively. The velocity of flow through the runner is constant and is equal to 1.8m/s. determine the discharge through the runner and the width at the outlet if the width at the inlet is 20 cm.

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88 D=12m 1.2m, D 1 =06m 0.6m. V f1 =V f =1.8 18m/s. Q = πdbv = π ( 1.2)0.2(1.8) = f

89 πdbv f = πd B 1 1V f V f = V f 1 DB = = D B 1 1 B 0.4 m = 40 cm. 1 = DB / D1 = 1.2(0.2) / 0.6

90 A reaction turbine works at 500 rpm under a head of 100m. The diameter of the turbine at the inlet is 100cm and the flow area is 0.35 sq.m. The angle made by the absolute and relative velocities at the inlet are 15 and 60 degrees respectively with the tangential velocity direction. Determine discharge, power developed, efficiency assuming that the velocity of whirl (Vw)at outlet is zero.

91 N = 500 rpm, H = 100m, D = 1m. Flow area πdb = 0.35m 2 α = 15; θ = V 1 = 0 w1 60;

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93 Velocity diagrams at the inlet and outlet are drawn. u = πdn / 60 = π (1 500) / 60 = 26.18m / s From the inlet triangle V f tan 15 = V = f V w 0.268V w

94 tan 60 = V f V u = V w V V w V = m / w w s V = ( 0.268) = 8.3m / f s

95 Q = πdbv = (0.35)(8.3) 3) = m / f 3 s Power developed = Work done/1000 KW = ρ QV u 1000(2.9053)30.973(26.18) w 1000 = 1000 = KW

96 Efficiency η h [ V u ] (26.18) V u = w gh = 9.81(100) = = 82.66%

97 An outward flow reaction turbine has internal and external diameters of 0.5m and 1.0 m respectively. Theguide blade angle is 15 degree and velocity of flow through the runner is constant and is equal to 3.0 m/s. if the speed of the turbine is 250 rpm, the head on the turbine is 10m, and the discharge at the outlet is radial, determine runner vane angles at the inlet and outlet, work done by the water on the runner per second per unit weight striking per second and hydraulic efficiency.

98 D=05m 0.5m, D 1 =1m; α = 15; V = V = 3m / s; N = 250rpm f f 1 H = 10m Discharge at the outlet is radial so V = ; = w 1 f 1 0 V V 1

99 Tangential velocity at inlet is u u = πdn / 60 = π ( ) / 60 = 6.545m / s Tangential velocity at outlet is u 1. u = π (1 250) / 60 = m / s 1

100 At inlet V f 3 tan 15 = = V V w 3 V = = m / w tan15 w s

101 Runner vane angle at inlet can be calculate by V f 3 tan θ = = u = V w θ = deg.

102 Runner angle at outlet tan φ = V f 1 u 1 = = φ = 12.9deg.

103 Work done by water per second per unit weight striking per second. As V w1 = 0 [ u] V w g = (6.545) 9.81 = N m / sec

104 η h [ V u ] V u = w gh = 10 = = %