论文总字数：23417字

摘 要

随着地球的日益开发以及化石燃料的逐步消耗，寻找一种新的燃料和燃烧技术迫在眉睫。寻找新燃料不仅有利于节能环保，更有利于可持续发展，而生物柴油便是一种可以满足需求的替代燃料，本文旨在研究生物柴油与柴油的掺混比例对整个燃烧排放过程的影响。

本文介绍了生物柴油的特性及在内燃机内的使用，并采用三维数值模拟代码耦合的KIVA4-CHEMKIN程序进行辅助计算，研究在不同转速条件下改变生物柴油与柴油的掺混比例对燃烧过程及排放的影响，并且研究通过改变纯生物柴油的喷油持续角对燃烧过程及排放的影响；研究得出，随着生物柴油掺混比例的增加，NO、CO的排放显著降低，若转速增加，排放CO略微降低NO略微上升；而改变喷油持续角在低转速条件下，喷油角越低，CO排放越高，与NO相反，综合CO与NO的排放可以选择喷油持续角在10.5°或15.5°左右；在高转速条件下，发现在9.5°喷油持续角时会导致燃料吸附在燃烧室底面，不利于使用，且4.5°持续角时已经超越了最大压力增长率，处于不安全工况，在高转速条件下推荐使用喷油持续角在19.5°或者24.5°左右的喷油持续角。

关键词：内燃机；数值模拟；生物柴油掺烧；持续角

Investigation on the combustion performance and emissions formation in a diesel engine fueled with blended biodiesel

Abstract

With the development of the earth and the gradual depletion of fossil fuels, it is urgent to find a new fuel and combustion technology. Looking for a new fuel is not only beneficial to energy conservation and environmental protection, but also more conducive to the sustainable development. Biodiesel is a kind of fuel that can meet the demand of alternative fuels. The purpose of this paper is to research of biodiesel and diesel blending ratio on the influence of the whole process of combustion and emissions formation.

This paper introduces the characteristics of biodiesel and its usage in internal combustion engine. The three-dimensional numerical simulation code, i.e., coupledKIVA4 - CHEMKIN program, was used in this research. The influence of different blending ratios and injection durations of biodiesel on the combustion process and emissions formation were investigated under the conditions with different rotating speeds. According to the research, with the increase of the mixing ratio of biodiesel, the emission of NO and CO is significantly reduced. When the speed increases, the emission CO will slightly decrease the NO. In addition, the change of injection duration under the condition of low rotational speed can also affect the emissions. With short injection duration, the CO emissions is higher. In contrast, NO decreases with short injection duration. With the consideration of CO and NO emissions, the injection duration around 10.5 ° and 15.5 ° can be chosen under the condition of high speed. It was found that the injection duration of 9.5 °will result in deposition of fuel on the combustion chamber bottom, which is not conducive to use. Also, the duration of 4.5 ° has transcended the growth rate of maximum pressure. Finally, it is recommended to use injection duration around 19.5 ° and 24.5 °.

Keywords: Internal combustion engine; Numerical simulation; Biodiesel blends; Spray duration

目录

摘 要 I

Abstract II

第一章 绪论 1

1.1 生物柴油的特点及研究意义 1

1.2 国内外生物柴油发展 2

1.2.1 国外生物柴油发展 2

1.2.2 国内生物柴油发展 4

1.3 生物柴油于内燃机的应用 4

1.4 本文的主要研究内容 5

第二章 数值模拟方法和实验过程 6

2.1 KIVA4-CHEMKIN介绍 6

2.2 化学反应机理 7

2.3 实验用生物柴油及内燃机介绍及模型验证 9

2.4 本章小结 11

第三章 生物柴油掺混柴油的燃烧与排放过程分析 12

3.1 燃烧过程分析 12

3.2 排放过程分析 16

3.3 经济性分析 22

3.4 本章小结 22

第四章 改变生物柴油喷油持续角的燃烧与排放过程分析 24

4.1 燃烧过程分析 24

4.2 排放过程分析 29

4.3 经济性分析 35

4.4 本章小结 36

第五章 全文总结与展望 37

5.1 全文总结 37

5.2未来展望 37

参考文献 38

致谢 41

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