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Combustion Physics

Combustion Physics. Nathan Paul 2/16/2012 Physics 575. Energy Consumption. ~75% of non-renewable energy consumption is accounted for by combustion methods. Within the renewable energy sector, ~50% is also accounted for by combustion.

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Combustion Physics

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  1. Combustion Physics Nathan Paul 2/16/2012 Physics 575

  2. Energy Consumption • ~75% of non-renewable energy consumption is accounted for by combustion methods. • Within the renewable energy sector, ~50% is also accounted for by combustion. 1 Municipal solid waste from biogenic sources, landfill gas, sludge waste, agricultural byproducts, and other biomass. 2 Fuel ethanol (minus denaturant) and biodiesel consumption, plus losses and co-products from the production of fuel ethanol and biodiesel. U.S. Energy Information Administration / Annual Energy Review 2010. Pg. 290. http://www.eia.gov/totalenergy/data/annual/pdf/aer.pdf

  3. Combustion Processes:Furnaces Power Plants Industrial Furnaces

  4. Other Types Jet Engines Explosions Rocket Engines

  5. Disco Inferno Burn, Baby. Burn.

  6. Internal Combustion Engines

  7. What is Combustion? • Reaction That Converts ‘Fuel’ and Oxidant to Bi-Products, Water and Energy. • Example Methane:

  8. INTERNAL ENERGIES AND ENTHALPIES OF IDEAL GASES Hess’ Law: If a reaction at constant pressure or constant volume is carried out in stages, the sum of the amounts of heat evolved in the separate stages is equal to the total when the reaction occurs directly OR The heat liberated by a reaction is independent of the path of the reaction between the initial and final states.

  9. Petroleum Combustion Process

  10. In Cylinder Pressure

  11. Lean and Rich • Lean Air to Fuel Ratio: • Rich Air to Fuel Ratio:

  12. Flame Propagation

  13. Flame Propagation • Temperature and Turbulence highly influence the flame speed. • Transient events and localized combustion reduce efficiency and create pollutants.

  14. Turbulence The turbulent flow distorts the flame so that the surface area is increased; The turbulence may increase the transport of heat and active species; The turbulence may mix the burned and unburned gases more rapidly Otto (SI) Cycle Diesel (CI) Cycle

  15. Emissions • Unburned Hydrocarbons • Too Lean; Too Rich; Too Cold; Wall Deposits; Misfires; Fuel Quality • Carbon Monoxide • Low Gas Temps; Low Oxidants; Short Burn Time • Nitrous Oxides • High Temp Regions; • Particulate Matter • Over fueling; Poor Combustion; Fuel Quality

  16. CO2 Emissions Transportation CO2

  17. Diesel Emission Regulations

  18. Other Possibilities? • Bio-Fuels • Hydrogen • HCCI

  19. Bio-FuelsEnergy and Emissions

  20. Hydrogen Enthalpy of Combustion for Hydrogen: 2 H2(g) + O2(g) → 2 H2O(l) + 572 kJ (286 kJ/mol) No CO2 Emissions; Some NOxEmisions

  21. Homogeneous Charge Compression Ignition (HCCI) PROS: • In diesel engines, soot is formed in the fuel rich regions and NOx in the hot stoichiometric regions. It is difficult to reduce both NOx and soot simultaneously. • The benefit with HCCI compared to the Spark Ignition (SI) engine is the much higher part load efficiency. Cons: • Difficult to control the ignition timing over a wide load and speed range • Higher emission of unburned hydrocarbons.

  22. Side Note: Importance of Efficiency LED vs Traditional Lighting Smart Grid Zero-Energy Buildings

  23. Efficiency of a SI Engine

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