大型低速二沖程柴油發(fā)動機具有較高的熱效率,動力性和耐久性等優(yōu)點。由于其高效率和高可靠性,大型二沖程船用柴油機成為貨船的主要動力。在不降低熱效率的情況下降低發(fā)動機排放是一項具有挑戰(zhàn)性的任務(wù)。實際上,燃燒效率和排放物形成都強烈依賴于燃燒特性,而燃燒主要決定于混合氣的形成,例如液滴的分解、蒸發(fā)和與空氣混合。同時,缸內(nèi)流動的影響在上述過程中起著重要作用。由于經(jīng)濟性的原因,現(xiàn)在都用重質(zhì)燃油(HFO)作為船舶的燃料,這些燃料含有大量輕質(zhì)燃料精煉后的殘留物,如硫和金屬。這種燃料粘稠度高,需要在發(fā)動機使用之前加熱。隨著人們環(huán)保意識的增強,為了限制和控制船舶有害物質(zhì)的排放。1997年9月27日,國際海事組織(IMO)與國際防止船舶污染公約(MARPOL)(73/78)簽訂了MARPOL公約,其中船用柴油機排放的NOx排放限值在附錄VI中明確規(guī)定,并于2005年5月19日對所有已簽署協(xié)議的船舶生效。船舶污染的國際公約(MARPOL 73/78)的附件六是使船舶空氣污染物合法化的主要國際公約,為降低海洋船舶排放氮氧化物提出了漸進的要求。NOx排放控制分為三個階段,第一階段氮氧化物排放限制適用于2000年1月...

【文章頁數(shù)】：70 頁

【學(xué)位級別】：碩士

【文章目錄】：
摘要
ABSTRACT
Chapter 1. Introduction
    1.1 Historical development and current trend of marine low-speed diesel engine
    1.2 Introduction to marine engine
        1.2.1 High speed marine diesel engine
        1.2.2 Medium speed marine diesel engine
        1.2.3 Low speed marine diesel engine
    1.3 Current research status of NOx emission reduction technology for marinelow speed diesel engine
        1.3.1 Gas fuel or dual fuel
        1.3.2 Optimize the fuel injection timing
        1.3.3 Exhaust gas recirculation
        1.3.4 Turbocharged
        1.3.5 Miller cycle
        1.3.6 Humidification technology
        1.3.7 Selective Catalytic Reduction
    1.4 Injection Process
        1.4.1 Direct Injection Diesel Engine
        1.4.2 Jerk Injection
        1.4.3 Common Rail Injection
        1.4.4 Timed Injection
    1.5 Combustion Process
        1.5.1 HCCI
        1.5.2 PCCI
        1.5.3 RCCI
    1.6 Summery
Chapter 2. Numerical Models
    2.1 Basic Control Equations
        2.1.1 Gas phase control equation
        2.1.2 Liquid Phase Control Equation
    2.2 Turbulence Model
    2.3 Spray Model
        2.3.1 Droplet Breakup Model
        2.3.2 Other Spray Models
    2.4 Combustion model
        2.4.1 The Shell Model
        2.4.2 Characteristic Time Scale Combustion (CTC) Model
    2.5 Emission model
        2.5.1 Soot model
        2.5.2 NOX Model
    2.6 Summary of this chapter
Chapter 3. Study of Spray Characteristic in Constant Volume CombustionChamber
    3.1 Calculation Conditions
    3.2 Verification of spray model
    3.3 Influence of Ambient Pressure
    3.4 Influence of swirl
    3.5 Influence of nozzle diameter
    3.6 Influence of injection pressure
    3.7 Influence of ambient temperature
    3.8 Influence of Injector Holes Position Variation
    3.9 Influence of Swirl
    3.10 Summary of this chapter
Chapter 4. Study on Heavy Oil Combustion and Emission in CVCC
    4.1 Calculation Conditions
    4.2 Effect of Oxygen Concentration on Combustion and Emissions
    4.3 Summary of this chapter
Chapter 5. Conclusion
References
Acknowledgement



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