Design Optimisation and Characterisationof a Crossflow Turbine

ByC.S. Kaunda

University of Dar es Salaam/NTNU02nd May, 2012

SupervisorsProf. Kimambo - UDSM

Prof. Nielsen - NTNU

ByC.S. Kaunda

University of Dar es Salaam/NTNU02nd May, 2012

SupervisorsProf. Kimambo - UDSM

Prof. Nielsen - NTNU

Outline of Paper Presentation• Introduction: Link between energy and

development: Scenario in sub-Saharan Africa (SSA)• Rural Electricity Supply Scenario in SSA• Microhydropower Technology – Status, Potential in

and Challenges in SSA• Crossflow Turbine Technology and

Microhydropower in SSA• Performance Challenges of Crossflow Turbines• Areas of Improvement• Conclusions

• Introduction: Link between energy anddevelopment: Scenario in sub-Saharan Africa (SSA)

• Rural Electricity Supply Scenario in SSA• Microhydropower Technology – Status, Potential in

and Challenges in SSA• Crossflow Turbine Technology and

Microhydropower in SSA• Performance Challenges of Crossflow Turbines• Areas of Improvement• Conclusions

Energy and Development• Modern energy supply such as electricity supports

achievement of MDGs.• Social and economic as well as environmental

management activities are supported bysustainable energy supply

• SSA (except South Africa) faces acute shortage ofmodern energy.

• Electricity scenario in most countries ischaracterized by low consumption, small generationcapacity/million people, unreliability of powersupply and low electricity supply levels.

• Modern energy supply such as electricity supportsachievement of MDGs.

• Social and economic as well as environmentalmanagement activities are supported bysustainable energy supply

• SSA (except South Africa) faces acute shortage ofmodern energy.

• Electricity scenario in most countries ischaracterized by low consumption, small generationcapacity/million people, unreliability of powersupply and low electricity supply levels.

Electricity access in 2009 - Regionalaggregates (IEA, 2010)

Region

Populationwithout

electricity

millions

Electrification rate

%

Urbanelectrificatio

n rate%

Ruralelectrificatio

n rate%

Africa 587 41.8 68.8 25.0

North Africa 2 99.0 99.6 98.4

Sub-Saharan Africa 585 30.5 59.9 14.2

Developing Asia 675 81.0 94.0 73.2

China & East Asia 182 90.8 96.4 86.4

South Asia 493 68.5 89.5 59.9

Latin America 31 93.2 98.8 73.6

Middle East 21 89.0 98.5 71.8

Developing countries 1,314 74.7 90.6 63.2

World* 1,317 80.5 93.7 68.0

Region

Populationwithout

electricity

millions

Electrification rate

%

Urbanelectrificatio

n rate%

Ruralelectrificatio

n rate%

Africa 587 41.8 68.8 25.0

North Africa 2 99.0 99.6 98.4

Sub-Saharan Africa 585 30.5 59.9 14.2

Developing Asia 675 81.0 94.0 73.2

China & East Asia 182 90.8 96.4 86.4

South Asia 493 68.5 89.5 59.9

Latin America 31 93.2 98.8 73.6

Middle East 21 89.0 98.5 71.8

Developing countries 1,314 74.7 90.6 63.2

World* 1,317 80.5 93.7 68.0

Electricity Consumption Levels (World Bank, 2009)

4532

Sub-Saharan Africa Electricity Consumption Level (kWh/Capita)

Electricity Consumption Level (kWh/Capita)

20291

1503

27151 46

922

265147 85

453

1576

121 86 111

635

1023

Electricity Access Levels in SouthernAfrica in 2005 (World Bank, 2008)

75

80

87

(c) Electricity Access Levels in Southern Africa (2005)

Urban Electricity Access Level (%) Rural Electricity Access Level (%)

26

45

16

23

2926

45

4

9

2 1 1 2

12

50

3

8

Angola Botswana DRC Lesotho Malawi Mozambique Namibia South Africa Zambia Zimbabwe

Microhydropower Technology• Hydropower technology using small-scale plants is well matured

(Khennas and Barnett, 2000; Kaldellis et al, 2005) and has been inuse for many years ago.

• Microhydropower is a subset in Small Hydropower (SHP)categorization: No international agreement upper level of SHP .Most EU (10 MW), SA (10 MW), USA (30MW), Brazil (30MW), China (50 MW)

• Microhydropower (MHP): Less than 100 kW mostly.• MHP used for both: electricity generation and mechanical power.• In SSA, technology brought by missionaries and early tea planters.• Ideal for rural electrification: rural institutional facilities such as

schools, health centres and markets• Considered renewable, but climate change (droughts and

desertification) affects MHP availability during particular monthsof the year.

• Hydropower technology using small-scale plants is well matured(Khennas and Barnett, 2000; Kaldellis et al, 2005) and has been inuse for many years ago.

• Microhydropower is a subset in Small Hydropower (SHP)categorization: No international agreement upper level of SHP .Most EU (10 MW), SA (10 MW), USA (30MW), Brazil (30MW), China (50 MW)

• Microhydropower (MHP): Less than 100 kW mostly.• MHP used for both: electricity generation and mechanical power.• In SSA, technology brought by missionaries and early tea planters.• Ideal for rural electrification: rural institutional facilities such as

schools, health centres and markets• Considered renewable, but climate change (droughts and

desertification) affects MHP availability during particular monthsof the year.

MHP Potential in SSACountry Identified Potential Declaration of Source

Malawi 7.4 MW Kaunda and Kimambo, 2011

Tanzania 185 MW Kabaka andGwang’ombe, 2007

Mozambique Over 1000 MW Hankins, 2009

Zimbabwe 120 MW Government of Zimbabwe,2009

Rwanda Over 300 sites identified.Total power potential notknown

Rwanda Utilities RegulatoryAgency , 2009

Rwanda Over 300 sites identified.Total power potential notknown

Rwanda Utilities RegulatoryAgency , 2009

Ghana 21 sites identified withpower potential rangingfrom 4 to 325 kW

Government of Ghana,2010

Kenya Over 3000 MW Government of Kenya, 2011

Uganda 210 MW Uganda Energy RegulatoryAuthority, 2007

Nigeria Over 3500 MW Sambo, 2009

MHP Application status in SSACountry SHP Installed Capacity Declaration of Source

Ethiopia 80 MW In Conference Proceedings:Ministerial Conference onWater for Agriculture andEnergy , Libya, 2008.

Kenya 15 MW Kipyego, 2011

Uganda 18 MW Uganda ElectricityRegulatory Agency, 2009Uganda ElectricityRegulatory Agency, 2009

Rwanda 6.5 MW Rwanda Utilities RegulatoryAgency , 2009

Tanzania 5.4 MW Kaunda et al, 2012.

South Africa 68 MW Renewable Energy inemerging and developingcountries Project: CountryReport, South Africa, 2006

Malawi 1.3 MW Kaunda and Kimambo, 2011

Zimbabwe 1.4 MW Tinarwo, 2009

Basic components and arrangement of atypical micro hydropower system , RoR

Weir

Penstock

Power canalForebay

Main River

Power houseElectromechanical system

Transmission systemto Load

Tail racewater

Main River

MHP Mechanical Power Generatingequipment - Turbine

• Grouped into Reaction & Impulseturbines

• Can be low, medium and high head• Francis, Kaplan, Propeller are reaction

types• Pelton Wheel, Turgo and Crossflow? Are

impulse type• Efficiencies high except Crossflow

• Grouped into Reaction & Impulseturbines

• Can be low, medium and high head• Francis, Kaplan, Propeller are reaction

types• Pelton Wheel, Turgo and Crossflow? Are

impulse type• Efficiencies high except Crossflow

Turbine Performance Curves (IPCC, 2011)

Crossflow Turbine Application range inMHP (Southeast Power Ltd, 2008)

Crossflow Turbine (CFT)• Relatively cheap as compared to others: per kW of installed

capacity, CFT has lower cost.• CFT runner relatively simple to manufacture – most of the local

workshops in developing countries have facilities to fabricate one.• CFT Impulse type of turbine as such able to handle poor water

quality in power production• CFT has ability to maintain optimum efficiency levels for a varied

flow• CFT Common in developing countries S.E Asia

(India, Nepal, Afghanistan et al).• CFT Technology is now becoming popular in some SSA countries

such TZ and MW. In TZ, most of the recorded MHP are of CFT.• In Tanzania, UDSM, Arusha technical college are involved in the

fabrication of the technology.• In Malawi, The Polytechnic and Malawi Industrial Research and

Technology Development Centre also involved in the fabrication.

• Relatively cheap as compared to others: per kW of installedcapacity, CFT has lower cost.

• CFT runner relatively simple to manufacture – most of the localworkshops in developing countries have facilities to fabricate one.

• CFT Impulse type of turbine as such able to handle poor waterquality in power production

• CFT has ability to maintain optimum efficiency levels for a variedflow

• CFT Common in developing countries S.E Asia(India, Nepal, Afghanistan et al).

• CFT Technology is now becoming popular in some SSA countriessuch TZ and MW. In TZ, most of the recorded MHP are of CFT.

• In Tanzania, UDSM, Arusha technical college are involved in thefabrication of the technology.

• In Malawi, The Polytechnic and Malawi Industrial Research andTechnology Development Centre also involved in the fabrication.

Crossflow turbine

Nozzle

Runner

Draft tube

Guide vane

Crossflow Turbine Runner

Runner blades

Bearing housing

Shaft

Bearing housing

Crossflow Turbine (CFT)• Due to its low efficiency levels, most of the turbine

manufacturing companies did not embark on improvingits performance studies for wide scale application.

• Performance studies on the CFT are relatively fewcompared to other types of turbines: CFT are lessefficient turbines (less than 80% practically possible)

• CFT poor performance is due to poor its poor internalflow profile in the runner.

• Studies concentrated on optimising the geometricdimensions of physical design parameters and varyingperformance.

• Due to its low efficiency levels, most of the turbinemanufacturing companies did not embark on improvingits performance studies for wide scale application.

• Performance studies on the CFT are relatively fewcompared to other types of turbines: CFT are lessefficient turbines (less than 80% practically possible)

• CFT poor performance is due to poor its poor internalflow profile in the runner.

• Studies concentrated on optimising the geometricdimensions of physical design parameters and varyingperformance.

Crossflow Turbine (CFT)In the design and optimization of the turbine, it is

important to evaluate :• How does the internal flow pattern affect the

hydraulic efficiency in the turbine?• How does the fluid velocity and pressure

distribution influence the turbine performance for agiven flow and head?

• What are the effects of changing geometric designparameters to the turbine performance?

In the design and optimization of the turbine, it isimportant to evaluate :

• How does the internal flow pattern affect thehydraulic efficiency in the turbine?

• How does the fluid velocity and pressuredistribution influence the turbine performance for agiven flow and head?

• What are the effects of changing geometric designparameters to the turbine performance?

Crossflow Turbine (CFT)• Flow profile can be characterized using Navier- Stokes

equations

• Flow in CFT is quite complex, 3d-dimensiona; and two phase.• Characterization and design optimization done by using CFD.

• Flow profile can be characterized using Navier- Stokesequations

• Flow in CFT is quite complex, 3d-dimensiona; and two phase.• Characterization and design optimization done by using CFD.

CFD Design Procedure

Conclusions• Capacity for CFT to be used in rural electricity

supply is high in SSA• Need to look at addressing technological issues that

hinder MHP development in the region. In this casesupporting local turbine manufactures with efficientdesign models will help.

• CFT design need to be looked at optimization theinternal flow profile. This may define the optimumsize of the turbine for particular site (head and flowrate) and flow conditions.

• Capacity for CFT to be used in rural electricitysupply is high in SSA

• Need to look at addressing technological issues thathinder MHP development in the region. In this casesupporting local turbine manufactures with efficientdesign models will help.

• CFT design need to be looked at optimization theinternal flow profile. This may define the optimumsize of the turbine for particular site (head and flowrate) and flow conditions.

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