A BRIEF INTRODUCTION - Iowa State University · PDF fileA BRIEF INTRODUCTION: Design Freedom,...

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A BRIEF INTRODUCTION: Design Freedom, mechanical Advantages and Economic Benefits of The New Updraft-Divergent-Flow Hydroturbine (K-Turbine) David T. Kao Professor & Dean Emeritus of Engineering College, Iowa State University November, 2009

Transcript of A BRIEF INTRODUCTION - Iowa State University · PDF fileA BRIEF INTRODUCTION: Design Freedom,...

Page 1: A BRIEF INTRODUCTION - Iowa State University · PDF fileA BRIEF INTRODUCTION: Design Freedom, ... Existing Hydro-Turbine Types. 3. High Head. ... Complex draft tube. Wicket Gates Control

A BRIEF INTRODUCTION:Design Freedom, mechanical Advantages and Economic Benefits of

The New Updraft-Divergent-Flow Hydroturbine (K-Turbine)

David T. KaoProfessor & Dean Emeritus of Engineering College, Iowa State University

November, 2009

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TECHNICAL BRIEFING

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Existing Hydro-Turbine Types

3

High Head Mid-High Head

Low-Mid Head Low Head-Bulb

P = η x 9.8 x Q x H

P = Out put (kW)Q = Flow (CMS)H = Head (M)η = Efficiency

= 1 – (Friction & Turbulent Losses)

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Elements of Conventional Turbines

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Francis Turbine Propeller Turbine

3-Gorges’ Runner

Complex draft tube

Wicket Gates Control

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The Key Design DifferencesBetween the Conventional (a) & the Updraft (b) Turbines

To a long draft tube (adds 25% cost)

Inflow

Wicket gates: Major causes of fish injury

High pressure shaft seal: need frequent maintenance

Runner

High water pressure zone

Negative pressure zoneMajor causes of fish mortality

Inflow

Does not need a draft tube

(b) Updraft design: light, simple & inexpensive; environmentally sound & fish friendly

D. T. Kao

(a) Downdraft design: heavy, complex & expensive; and can cause heavy fish injury & mortality

(a) (b)

To Generator

OutflowOutflow

Outflow

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The New System Features Four Crucial Design Innovations:

1) An updraft flow arrangement; 2) A vertical pressure-balanced turbine flow

control valve to replace conventional closely spaced wicket gates;

3) A divergent runner flow chamber to recover kinetic energy (KE) without using the costly draft tube; and

4) Turbine flow exits at the free surface in the tailwater terrace to aerate and improve exit flow water quality.

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Advantage: Easy Installation -- The new K-turbine is easy to install and maintain

The Fundamental Fluid Mechanics Principle: The energy input to both turbines, for the same flow, Q, and head, H, is the same regardless of the turbine flow direction.

Conventional downdraft flow Turbine require costly draft tube

HQ

Innovative K-Turbine can be used for new power station or to retrofit on existing dams

H

Q

7

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Self KE Recovery & Aeration-- Saves system cost & improves downstream water quality

Gradually decreasing flow velocity in the divergent turbine runner chamber (CFD results) results in recovering 90% or more KE

The residual kinetic energy (KE) generates flow aeration & air entrainment actions (shown during the test) to improve downstream water quality

D. T. Kao

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Open Flow Passage With No Cavitation – Minimizes injure & mortality of passing fish

9D. T. Kao

CFD simulation shows less grinding and striking injures to the passing fish

No negative cavitation pressure to cause fish mortality due to internal injury

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Experimental Results shows Safe fish passage through the New Turbine with no Negative (Cavitation) Pressure

Experiment Set-up

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Flow Pattern and Efficiency

Outflow

Inflow

Design flow Q = 25.35 CMSDesign head H = 15 MTurbine Diameter = 2.04 MPeak Eff. = 88.2%

Arrows shoe 3-D velocity vectors along the blade (CFD flow pattern analysis)

-- Parallel velocity vector indicates smooth flow that helps to eliminate blade vibration & reduced energy loss

D. T. Kao

[ ]

D = 20.3 cm (8 inches)H = 1.38 MQ = 0.048 CMSPeak Eff . = 86.15 %Analytical & experimental results

show that the new hydroturbine is highly efficient even at micro size

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Projected Performance Comparison

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0

0.2

0.4

0.6

0.8

1

1.2

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

Relative Power

Rel

ativ

e Ef

ficie

ncy

Propeller Turbine (data) Kaplan Turbine (data) Kao Turbine (CFD)

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Summary on The Competitive Advantages of the K-Turbine

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Saves 35 to 66% station cost

3 to 8% more efficient

Easier to maintain

Improves water quality

Minimizes fish injury and mortality

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Prototype 7-kW K-Turbine andCFD Analysis Results

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Computational Fluid-Dynamics (CFD) analysis results on Pressure distribution on the pressure-side of the K-turbine runner blade.

CFD analysis results on streamline pattern inside the spiral case of the K-turbine.

Prototype 7-kW K-turbine.

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MARKET POTENTIAL

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The Opportunity:Huge Untapped Global Hydropower Resources

79% of global hydropower resources remain untapped (~ 1,760,000 MW) The equivalent of approximately 3,000 nuclear power plants

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78%93%

67%

31%25%

30%

Relative Size of Reserves by Continent% Untapped Reserves by Continent

Source: International Hydropower Assoc.

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The Problem: Lack of Technology to DevelopPico to Small Hydropower Resources

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Less than 15% untapped resources in large-hydro (>1,000MW) sites

!More than 85% untapped resources in pico to medium size sites (*)

3 gorges dam, 22,500 MW

Hoover dam, 2,080 MW

------------------(*) Pico (<10kW), Micro (<100kW), Mini (<1MW), Small (<25MW), and Medium scale (<250MW) hydropower sites

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Shortcomings of Existing Hydropower Turbine Technology

The Idaho National Laboratory, US DOE web declares: “Current hydropower technology, while essentially emission-free, can have undesirable environmental effects, such as fish injury and mortality from passage through turbines, as well as detrimental changes in the quality (dissolved gases) of downstream water.”

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There is great demand for Innovative Eco-environmental friendly turbine technology!

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We Call Those

“The 5-E Advantages”:

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EconomicalEfficientEasyEcologically friendlyEnvironmentally sound

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Approximate Application Ranges of Various Type Hydro-Turbines

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Micro- Mini- Small- Medium- Large-turbines

Turbine Output (kW)| | | | | |

1 10 100 1,000 10,000 100,000

1,000

100

10

1

__

__

__

__

Water Head (M)

Pico-

Conventional Francis-turbine and Kaplan-turbine

Innovative Kao-turbine

Scale down Conventional turbine

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K-Turbine Has Broad Application Ranges and Is Highly Competitive

Applicable Ranges• Water Head: 1 to 80 M• Power Output: kW to MW

Competitiveness• Environmental Advantages• Cost Less• Easy to Install, Operate, and

Maintain

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kW - prototype

MW- CAD illustration

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1 ~ 25 MW

Market Development Strategy- Start small & grow

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Estimate Pico- Market: 4 Million Units

Source: IT Power of UK, 2006

Pico- to Micro-

Mini- to Small-

Medium-to Large

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kW unit

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Easy Installation on New or Existing Dams Example: Potential hydropower generation from irrigation water release

with its energy being currently mechanically dissipated

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Existing dam

Enough power for 1.3 MW with 2 units

Connecting pipes

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The New K-Turbine Can Effectively Compete in Exiting & New Market Categories: New power stations Old station turbine replacement Retrofitting on existing dams Distributed peak-power supply Low-head large-flow market needs Environmental flow power generation Energy storage for solar & wind power Remote areas basic energy supply needs

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