ENERGY AND POWER CONVERSION DEVICES

Chapter 13

Objectives

List types of E & P conversions that can occur

Identify devices used to convert forms of E&P into other forms of E&P

Describe operation of devices for conversions

Explain new conversion devices not yet routinely used

Calculate the efficiency of various E&P conversion devices

FOUR types of Conversions

Power Conversion (Power to Power) Energy Conversion (Energy to Power) Frequency Conversions (Energy to

Energy) Energy Inversion (Power to Energy)

Power Converters

Change one form of power to another (power to power) Most common conversion devices Electrical Fluid Mechanical

Electric Motor: Converts one form of power (electrical) Into another form of power (mechanical)

Power Conversion:Electrical to mechanical Solenoid (very common) is a coil of wire

with movable steel core in the middle When coil is charged creates a magnetic

field (electromagnet) The core moves in a linear fashion ie. door latches, door bells, relays

Power Converter: SolenoidElectrical to Mechanical Why use a solenoid relay….

Allows power to be cut from many locations Can be operated with very little power

Avoids running large wires to all locations

Small wires are less expensive and easier to work with

ie. Your car’s starter works with a solenoid

ie. Used to open and closes valves allows central control

Power Conversion:Electric Motors

70% of all electricity generated is used to operate electrical motors.

All work on same principle Magnets provide north and south polarity

(magnetic field) When wire placed between poles a current is

“induced” (made to flow) in the wire Current flowing in wire generates another magnetic

field around wire Magnetic fields pull and push each other to create

motion Quickly changing polarity of electromagnet sustains

motion

Power Conversion: DC Electric Motor

Fixed magnets Armature A series of wires wrapped

around a metal core that is Free to rotate

Brush contactors Supply electricity to the

armature Commutator (slip ring)

circular conductive strip attached to armature

Reverses flow of electricity every half turn

Power Conversion: AC Induction Motor Uses Electromagnets – which can

produce stronger magnetic fields resulting in more powerful motors

Stator- electromagnets attached to the housing (replaces the fixed magnets)

Rotor- spinning coil of the motor that is connected to the motor shaft

Power conversion: AC Induction Motor

Start windings: special set of stator windings

Single phase induction motors - have only one set of stator windings Require start winding

Three phase induction motor (polyphase motors)- stator windings are arranged 120-deg out of phase with each other No start winding required Industrial use – very

powerful

Power Conversion:Mechanical to Electrical Generators- wire (armature) is moved

through a magnetic field inducing voltage (sound familiar?)

Wire moves through the magnetic lines of flux producing voltage

Increased wire movement OR increased magnetic field = stronger induced voltage

In a real generator electromagnets are used to produce strong magnetic fields AND the armature spins at high RPMS this produces very strong voltage

Power Conversion: Mechanical to Fluid Pump is used to convert mechanical

power into fluid power (by pressurizing fluid)

Mechanical motion pressurizes fluid which is used to perform work

Reciprocating pumps or rotary vane pumps are examples

Power Conversion:Fluid to Mechanical Use of cylinders (actuators) to convert

pressurized fluid into linear mechanical movement.

Vane motor is just like rotary vane pump but pressurized fluid flows in the opposite direction and drives rotor.

Power Conversion: Fluid to Electrical Converting electricity directly into fluid

motion OR fluid motion directly back into electricity.

Magnetohydrodaynamic (MHD) Generator Experimented with in the 1960s but left

behind in favor of nuclear development Similar to a generator (mechanical to

electrical) but using conducting gas plasma instead of metal conductor like a wire

Magnetohydrodynamic (MHD) Generator:

Advanced system to develop electricity directly from heat source (fossil fuels) but still in the research stages

More efficient than conventional generating plant Fuels are burned at very high temperatures Gases from high temperature combustion are made

electronically conductive by seeding with conductive chemicals

Very hot ionized gas takes the place of copper windings traveling at high speed through a magnetic field to produce DC electricity

Waste heat can be used to boil water and turn traditional turbine generators (1.5 times more efficient than conventional power plant)

Magnetohydrodaynamic (MHD) Generator:

Power Conversion: Electrical to Fluid Electromagnetic

induction pump without any moving parts can propel a liquid as long as the liquid can be polarized

ie. Moving mercury around using a magnet or submarine propulsion ????

Energy Converters

Changes form of Energy into a form of Power

Energy Conversion: Energy into Power Visible light to

electrical Power: Photovoltaic cells:

convert sunlight directly into electrical power

Photocells: (electric eyes) photons strike sensors that create small electric current that triggers a transistor to open or close a circuit.

Energy Conversion: Infrared Energy to Mechanical Power

Thermostat detects temperature and converts changes into mechanical power Opens or closes electrical power electrical

switch contacts to turn AC on or off. Bimetallic coil-made from strips of two

metals with different Coefficients of expansion (the rate at which a metal expands or contracts with changes in temperature) Coil tightens when cold, and expands when

warm

Thermostats With Bimetallic CoilInfrared to Mechanical Power

Energy Conversion: Sound Waves to Electrical Power Sound travels @ 3-miles/second through

steel Electricity travels at 186,000 miles/second Faster to convert sound into electrical

impulses for transmission over distances Microphone does this and speakers convert

electrical impulses back into sound. Same basic concept as electrical motors /

generators

Energy Conversion: Chemical Energy to Mechanical Power Internal Combustion Engine is one

example Chemical energy (gasoline) Converted to heat during combustion Converted to fluid power (expanding

gasses) Converted to mechanical power (gasses

push on mechanical components and move them)

Frequency Converters

Change one frequency (wavelength) of radiant energy into another frequency of radiant energy

Frequency Conversion

One frequency of radiant energy is converted into another frequency of radiant energy. Frequency: the number

of cycles in a given time interval (one second)

Hertz: a complete wavelength from start to finish

Frequency Conversion: Radiant Energy to Chemical Energy Occurs naturally all the time in…. Photosynthesis- carbohydrates are

compounded from carbon dioxide and water in the presence of sunlight and chlorophyll

Primary method of bioconversion of solar energy into all others

Frequency Conversion: Chemical Energy to Radiant Energy Through process called ….. Combustion: the rapid chemical reaction

in which heat and light are produced Requires oxidation: a union between fuel

and oxygen

Frequency Conversion: Visible Light to Infrared Light Happens when visible light strikes

something Solar collectors are designed to

maximize the conversion and capture the energy from the heat

Frequency Conversion: Ultra-Violet Radiation to Visible Light Florescent bulbs

Electrodes are heated by electrical current and emit free electrons

Electrons strike atoms of mercury vapor

Mercury vapor emits radiant energy in the form of UV Radiation.

UV radiation strikes phosphor coating on bulbs and conversion to visible light occurs.

Energy Inverters

Changes a form of Power back into a form of Energy

Energy Inverters: Electrical Power to Visible Light

Two methods of producing artificial light Heating something until

it “glows.” standard incandescent bulbs heat tungsten until it glows white hot, producing light.

Pass electricity through a gas of vapor causing tiny charged particles within the atoms to glow like Halogen bulbs

Energy Inverters: Electrical Power to Infrared Energy Electrical power to heat energy is

common Electrons flow through a wire exciting

molecules within the wire. Increased agitation causes molecules to

move Movement generates excessive energy,

given off in the form of heat ie: space heater, toasters, burners

Energy Inverters: Electrical Power to X-Radiation X-ray tube converts

electrical power into x-radiation (higher frequency than visible or UV light) Negatively charged

electrons strike a tungsten filament (like a light bulb)

Tungsten then emits x-rays

X-rays pass through lighter atoms but they are absorbed by more dense materials.

Energy Inverters: Electrical Power to Sound Waves Speakers!!!!! Work based on Principle of Magnetism:

like forces repel one another and opposing magnetic forces attract one another

Contains electromagnet attached to cone that receives signal creating electrical field. Magnet in the base repels or attracts depending on the signal causing cone to move