Card Set Information

2013-12-07 13:42:42

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  1. Hydroelectricity
    Energy of falling water
  2. Head
    Vertical fall
  3. Power equation derivation
    • The power of water:
  4. Francis Turbine diagram
  5. Francis Turbine traits (5)
    • most common type
    • medium or large scale plants
    • completely submerged
    • radial and axial flow (mixed flow) turbine
    • medium head
  6. Francis Turbine working principle
    Water enters radially and emerges out axially so the discharge is parallel to the axis of shaft
  7. Francis Turbine maximizing efficiency
    Adjustment of the pitch -> we can change the angle of the blades to match the new conditions, can reduce the output power by turning the guide vanes when demand falls
  8. Kaplan Turbine (Reaction turbine) Diagram
  9. Kaplan Turbine traits (3)
    • Axial flow turbine
    • Rapid rate of revolution
    • Require large quantity of water (low head)
  10. Kaplan Turbine improved efficiency
    Change the angle of blades when the power demand changes
  11. Pelton Wheel (Impulse turbine) Diagram
  12. Pelton Wheel traits (4)
    • Require lower quantity of water
    • High heat turbine
    • Tangential flow turbine
    • Has double cups
  13. Turgo Turbine
    Variant of the Pelton Wheel - vary cup depth
  14. Hydroelectricity Diagram
  15. Types of flow direction (4)
    • Tangential
    • Radial
    • Axial
    • Mixed (radial and axial)
  16. Types of actions of flowing water
    • Reaction
    • Impulse
  17. Impulse Turbine
    The water hits the turbine as a jet in an open environment with the power deriving from kinetic energy of the flow
  18. Reaction Turbine
    The turbine is totally embedded in the fluid and is powered from the pressure drop across the device
  19. High Head
    • Greater than 250m
    • Pelton Wheel
    • Impulse turbines

  20. Medium Head
    • 50m to 250m
    • Francis Turbine

  21. Low Head
    • Less than 60m
    • Kaplan Turbine
    • Reaction Turbine

  22. Propellers Diagram
  23. Propellers
    • Axial-flow turbine
    • Area that water enters is the entire swept area
    • Good for large volume (low head) flows
  24. Cross-flow turbines
    • Impulse type
    • Water enters in a flat sheet rather than a round jet
  25. Hydroelectric Advantages (9)
    • Infinitely renewable
    • No fuel required
    • Non-polluting
    • 80% efficiency
    • Flood water can be used for agriculture
    • Long life equipment
    • Limited required maintenance
    • long lasting
    • last for 50+ years
  26. Hydroelectric Disadvantages (5)
    • People need to be evacuated to make room
    • Landscape clearing results in soil erosion
    • Limited natural flow in summer period
    • Bad for fish (Increase in T causes O2 levels to drop)
    • Killing of fish in turbines