Fluid Mechanics for Power Generation

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Fluid Mechanicsfor Power Generation

• P M V Subbarao
• Associate Professor
• Mechanical Engineering Department
• IIT Delhi

An Essential Science for All Thermal Processes
!!!!!
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• As early as 400,000 BC, fire was kindled in the
  caves of Peking man.

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The Aelopile Generation of Mechanical Motion

• In 130BC. Hero, a Greek mathematician and
  scientist is credited with inventing the first
  practical application of steam power, the
  aelopile.
• Simply a cauldron with a lid, the aelopile had
  two pipes that channeled steam into a hollow
  sphere.
• The sphere, which pivoted on the steam pipes, had
  two nozzles situated on opposite sides of its
  axis.
• Thus, the cauldron was fired, the water in it
  boiled, the steam was channeled into the sphere,
  and as the steam escaped through the nozzles, the
  sphere would spin.
• It was a thought the device and a novelty.

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Truths of Modern Life
Using the steam/Gas to make the Electric Power
! Rotating the shaft(Rotor) is the ultimate goal
of any power plant !!! How do you get mechanical
power from Live-steam or Gas? How to get
super energized (Live) steam/Gas ? How do u
generate life in live-steam ? A science of Fluid
Power is basis for all current and future power
generation technologies. This Science of Fluid
Power is called Fluid Mechanics.
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Philosophy of Fluid Power

• Present and future power generation technologies
  are based on
• Conversion of any natural power into fluid power.
• Transfer fluid power to shaft power.
• Conversion of shaft power into Electric power.
• Basic laws of Fluid power based power generation.
• Impulse principle
• Reaction principle
• Impulse-reaction principle
• Aerofoil theory.
• Every Power Engineer should study FLUID MECHANICS.

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Further Applications of Fluid Mechanics

• Transportation of Fuel.
• Internal supply of fuel and air through the fuel
  handling equipment.
• Internal circulation of flue gas and steam
  through steam generator Condenser.
• Operation of all journal bearings.
• Operation of all the pumps, fans compressors.
• Operation of Many control systems.

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Fluid Mechanics

• P M V SUBBARAO
• Associate Professor
• Mechanical Engineering Department
• IIT Delhi

A Science, which devalued the importance of time
!!!!
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Time A Pseudo Scientific Firm Concept

• A powerful pseudo concept.
• Became an utmost important in engineering and
  science after Newton.
• Changes with respect to time, in a body is the
  core of Engineering.
• But Past and Present are more known than the
  future.
• Past and future are not two distinct entities
  like Delhi and Mumbai.
• ..
• Present day Engineering and Science is strongly
  centered around Time base.
• Fluid Mechanics reduces the weight of time in
  Engineering.

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Energy and Power

• The scalar product of force and displacement is
  Work.
• Capability to execute a work is energy.
• Rate of doing work or rate of change in energy is
  Power.
• Finally Generation of Power is a temporal act.

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Newtons Second Law for Flow Device
V2
V1
V1
V2
V1
V2
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Newtons Second Law for Flow Device
Newtons Force
All quantities are invariant in time. Vary in
spacial direction only. Still it is possible to
accomplish Power Generation. More Advanced
systems are more invariant with time.
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Stage of A Turbine
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Sequence of Energy Transactions
Steam Thermal Power
Blade kinetic Power
Steam kinetic Power
Nozzle Losses
Stage Losses
Moving Blade Losses
Isentropic efficiency of Nozzle
Blade Friction Factor
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Fluid Dynamics of Coal Preparation Supply

• BY
• P M V Subbarao
• Associate Professor
• Mechanical Engineering Department
• I I T Delhi

Aerodynamics a means of Transportation
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Major Components of Coal Fired Steam Generator
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Schematic of typical coal pulverized system
A Inlet Duct B Bowl Orifice C Grinding
Mill D Transfer Duct to Exhauster E Fan Exit
Duct.
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Velocity through various regions of the mill
during steady operation
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Cyclone-type classifier.
Axial and radial gas velocity components
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Centrifugal Classifiers

• The same principles that govern the design of
  gas-solid separators, e.g. cyclones, apply to the
  design of classifiers.
• Solid separator types have been used
  preferentially as classifiers in mill circuits
• centrifugal cyclone-type and gas path deflection,
  or
• louver-type classifiers.
• The distributions of the radial and axial gas
  velocity in an experimental cyclone precipitator
  are shown in Figures.
• The flow pattern is further characterized by
  theoretical distributions of the tangential
  velocity and pressure, the paths of elements of
  fluid per unit time, and by the streamlines in
  the exit tube of the cyclone.

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Particle Size Distribution--Pulverized-Coal
Classifiers

• The pulverized-coal classifier has the task of
  making a clean cut in the pulverized-coal size
  distribution
• returning the oversize particles to the mill for
  further grinding
• but allowing the "ready to burn" pulverized coal
  to be transported to the burner.
• The mill's performance, its safety and also the
  efficiency of combustion depend on a sufficiently
  selective operation of the mill classifier.

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Mill Pressure Drop

• The pressure loss coefficients for the
  pulverized-coal system elements are not well
  established.
• The load performance is very sensitive to small
  variations in pressure loss coefficient.

Correlation of pressure loss coefficient with
Reynolds number through the mill section of an
exhauster-type mill.
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Fundamentals of Fluid Mechanics
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Introduction

• Fluid mechanics is the science of fluids either
  at rest (fluid statics) or in motion (fluid
  dynamics) and their effects on boundaries such as
  solid surfaces or interfaces with other fluids.
• Definition of a fluid a substance that deforms
  continuously when subjected to a shear stress.

• Consider a fluid between two parallel plates,
  which is subjected to a shear stress due to the
  impulsive motion of the upper plate
• No slip condition no relative motion between
  fluid and boundary, i.e., fluid in contact with
  lower plate is stationary, whereas fluid in
  contact with upper plate moves at speed U.

• Fluid deforms, i.e., undergoes strain ? due to
  shear stress t

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