Background for IC Engine Lab - PowerPoint PPT Presentation

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Background for IC Engine Lab

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  1. Background for IC Engine Lab • Review of Thermodynamics • Fundamentals of Combustion • Engine Emissions and Smog • 3-Way Catalytic Converter • Objectives of Lab • Overview of Lab System

  2. IC Engine: Theremodynamics • engine\applet.htm • P-V diagram: Work • Thermal Efficiency: Work/Heat Otto Cycle: = • Energy Balance: Heat Losses

  3. Fundamentals of Combustion • Fuel + Oxidizer -> Products • Chemical Reaction-> Heat Release • Heat of Combustion

  4. Properties of Common Fuels

  5. Combustion Chemistry • Overall Description of Chemical Reaction CnHm +[ (n+m/4) / )x4.7619 (0.21O2 +0.79N2)= np{ XCaHb CaHb + XCO2 CO2 + XCO CO + XH2O H2O + XO2 O2 + XN2N2}, where = Equivalence Ratio Octane = C8 H18; n=8, m=18

  6. Equivalence Ratio • > 1 Rich mixtures : too much fuel • < 1 Lean mixutres : too much oxidizer • =1 Stoichiometric : perfect condition ** Note many countries use air-fuel ratio: =A/F = stoich / actual

  7. Emissions from IC Engines • Unburned Hydrocarbons (HC), Soot, CO • Nitrogen Oxides: NOx (NO+ NO2) • N2+O - > NO + N (R1) • N+O2 -> NO + O (R2)

  8. Emissions as function of air-fuel ratio

  9. Smog • What is smog? The term "smog" was first coined more than three decades ago to describe a mixture of smoke and fog in the air • Smog is the popular name for the brownish-yellow haze that hangs in the warm, still air over many North American cities. • Smog is made up, in large part, of ozone gas.

  10. Smog (O3+PAN) • Nitrogen Oxides: These are produced when fossil fuels like gasoline, natural gas, heating oil and coal are burned. These gases are also produced naturally by forest fires, volcanoes and soil. • Volatile Organic Compounds (VOCs): These come mainly from the evaporation of liquid fuels, solvents and organic chemicals (nail polish remover, barbecue starter, paints, cleaners) and from burning gasoline. VOCs are also produced naturally by trees in cities and forests.

  11. Chemistry of Photochemical Smog • Sunlight. • The production of oxides of nitrogen (NOx). • The production of volatile organic compounds (VOCs). • Temperatures greater than 18 degrees Celsius.(T> 18 oC)

  12. Chemistry of Photochemical • Ozone (O3) and PeroxyAcetyl Nitrate (PAN) { R-C-O-O2-NO2} NO2 + sunlight »»» NO + O O + O2 »»» O3 NO2 + R »»» products such as PAN Symbol R represents a hydrocarbon (a molecule composed of carbon, hydrogen and other atoms) which is primarily created from volatile organic compounds

  13. Typical Exhaust Emissions From Gasoline Engines

  14. Emission Controls

  15. Three-Way Catalyst • The precious metals currently used in three-way catalyst applications are platinum, palladium and rhodium.

  16. Three-Way Catalyst • Rhodium has proven to be an efficient catalyst for NOX reduction. • Palladium and platinum metals are used in CO and hydrocarbon oxidation reactions. • 2 CO + O2 → 2 CO2 • 4 CnHm + (4n + m)O2 → 4n CO2 + 2m H2O • 2NO + 2 CO → N2 + 2CO2

  17. Three-Way Catalyst

  18. Three-Way Catalyst- T Effect • Conversion as a function of temperature: rate controlling regimes

  19. Three-Way Catalyst • Automotive emission control system showing the pre- and main catalytic converters

  20. Three-Way Catalyst:  Effect • The conversion efficiency (%) of a three-way catalyst as a function of A/F-ratio. An A/F-ratio of 14.6 corresponds to stoichiometric gasoline-air combustion. Rich Mixtures Lean

  21. IC Engine Lab dynamometer

  22. IC Engine Lab

  23. IC Engine Lab • Overall Objectives • a)   Thermodynamics cycle efficiency and P-V diagram of the actual cycle, • b)  The most important parameter(s) controlling engine power, • c)  The optimal speed for best fuel economy, and • d) The best operation condition that yields the lowest pollutant emissions. • e) Effects of turbocharger, intercooling, timing

  24. Schematic of Lab System

  25. Turbocharger for IC Engines

  26. Principles of Turbochargers

  27. Turbochargers

  28. Orifice Plate: Flow Measurement Connected to manometer

  29. Manometer • p=gh = fluid density g= gravity force h=height • http://www.efunda.com/formulae/fluids/manometer.cfm

  30. Principle of Eddy-Current Electro Brake Dynamometer • The current through the stator becomes heat on the stator. Rotational movement is coverted into heat by braking and heat is removed by coolingwater.

  31. Applications withDynamometer

  32. Large 2-Stroke Diesel Engines http://www.bath.ac.uk/~ccsshb/12cyl/

  33. Large 2-Stroke Diesel Engines • The cylinder bore is just under 38" and the stroke is just over 98".  Each cylinder displaces 111,143 cubic inches (1820 liters) and produces 7780 horsepower.  Total displacement comes out to 1,556,002 cubic inches (25,480 liters) for the fourteen cylinder version. •      Some facts on the 14 cylinder version:Total engine weight:2300 tons  (The crankshaft alone weighs 300 tons.) Length:89 feet Height:44 feet Maximum power:108,920 hp at 102 rpm Maximum torque:5,608,312 lb/ft at 102rpm      Fuel consumption at maximum power is 0.278 lbs per hp per hour (Brake Specific Fuel Consumption).  Fuel consumption at maximum economy is 0.260 lbs/hp/hour.  At maximum economy the engine exceeds 50% thermal efficiency.  That is, more than 50% of the energy in the fuel in converted to motion.     For comparison, most automotive and small aircraft engines have BSFC figures in the 0.40-0.60 lbs/hp/hr range and 25-30% thermal efficiency range.