Energy and Power Conversion Devices

1. Energy and Power Conversion Devices Chapter 13

2. 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

3. FOUR types of Conversions • Power Conversion (Power to Power) • Energy Conversion (Energy to Power) • Frequency Conversions (Energy to Energy) • Energy Inversion (Power to Energy)

4. 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)

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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.

14. 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

15. 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)

16. Magnetohydrodaynamic (MHD) Generator:

17. 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 ????

18. Energy Converters • Changes form of Energy into a form of Power

19. 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.

20. 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

21. Thermostats With Bimetallic CoilInfrared to Mechanical Power

22. 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

23. 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)

24. Frequency Converters • Change one frequency (wavelength) of radiant energy into another frequency of radiant energy

25. 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

26. 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

27. 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

28. 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

29. 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.

30. Energy Inverters • Changes a form of Power back into a form of Energy

31. 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

32. 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

33. 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.

34. 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