Combustion - 國立中央大學機械工程學系

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1.2.2 <strong>Combustion</strong> needs fuele.g. diesel oil gasoline engine• Emphasis on CoalNarrow compositional specifications of gases used in domesticgas rangesEnergy Crisis ≡ Fuel CrisisShortage & reliability of petroleum supplyDirect utilizationFluid bed combustionCoal-derived fuels· Higher boiling pt.· Wider boiling pt. ranges· Higher contents of aromatics andnitrogen containing compounds· more soot & NO 2Advantages:· Direct contact with air· max. burning rates· SO 2 (limestones)· NO 2 (↓; fluidization rate)Coal-water slurries• Finely crushed coal particles40 ~ 70 μm• mixed in water• Sprayed directly → combustion chamber of industrial furnaces• Advantages: less energy expansive than the chemical processes ofcoal liquefaction. easy to transport in pipes min. hardware modification of oil-fired combustor• 70% coal content of slurries have been successfully burned• Alternate & Hybrid Fuelse.g. Methanol & Ethanol & Ethanol with oilNatural gas & coal biomass Ethanol: smaller heats of combustion(∵ extra oxygen atom in the mlc.)Blends of 10% ethanol and 90% gasoline have been successfully burned in IC engines8
without any engine modification. However, corrosions in engines may be a problem.1.2.3 Pollution and HealthMajor Pollutants from <strong>Combustion</strong>Soot SO xNO xUHC COCoal-derived fuels Burning coal N 2in atm (unburned (carbonDiesel engine Sulfuric acid N in fuel hydrocarbon) monoxide)Carcinogenic Water in atm Thermal NO x(organic liquid Acid Rain ---High T.combustion products(Qdissociate inert N 2in air)condense on the aquatic life Fuel-bound NO x---less T.surface of the soil erosion sensitive major contributorsoot particles)(burning coal or coal-derived oils)致癌物質 ; 成癌質NO x reacts w / UHC & ozoneby sunlight smog (smoke + fog)Detrimental to the respiratory sys.Indoor Pollution (CO, NO x , UHC)• Domestic heating devicesgas rangesfurnacesKerosene heatersIncineration (chemical hazardouswastes)The uncertainty of the toxicity of thecombustion intermediates and productse.g. Halogenated Compounds( 鹵素 )( 氟、氯、溴、碘 )incineration resistant9
Page 2 and 3: Course ContentChapter 1 Introductio
Page 4 and 5: Chapter 1 Introduction to Combustio
Page 10 and 11: 1.2.4 SafetyFires Explosions Materi
Page 12 and 13: Finite reaction rates >> Thermodyna
Page 14 and 15: • Nonpremixed system abound.Indee
Page 16 and 17: Chapter 1 Introduction to Combustio
Page 18 and 19: Ch 1 Introduction to Combustion ME7

Combustion - 國立中央大學機械工程學系

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