摘 要

随着社会的进步，我国人均收入水平得到极大提高，同时汽车的价格也在不断下降，近年来，我国汽车保有量快速增长，专家预测到2020年我国汽车保有量将达到2.8亿辆。随之能来的能源危机和环境污染问题将会越来越突出，因此，寻找传统石化柴油的替代燃料成为国内外学者的研究热点。生物柴油以其良好的可再生性和清洁性，被认为是传统柴油的理想替代燃料，但也存在低温流动性和雾化性能差的缺点。四氢呋喃是一种性能优良的溶剂，本文从燃料设计角度，探究生物柴油掺混四氢呋喃的燃烧及排放特性。

首先，分别配制THF质量分数为0%、10%、20%、30%的THF-生物柴油测试燃料，将上述四种测试燃料分别记为T0、T10、T20、T30。在发动机台架上，通过负荷特性试验，研究了四种测试燃料在不同负荷下的燃烧及排放特性，此外，还利用AVL-Fire的ESE DIESEL模块研究了，在低温燃烧模式下，EGR对T20的燃烧和排放的影响。

最后，试验数据表明，（1）生物柴油中掺混四氢呋喃比例越大，滞燃期越长，燃烧持续期越短，但T30的燃烧持续期在0.13MPa负荷下显著延长。负荷越大，各燃料滞燃期越短，燃烧持续期越长。（2）生物柴油中掺混四氢呋喃比例越大，缸压及放热率曲线峰值越高；负荷越大，四种燃料的缸压及放热率曲线峰值差别越小。（3）生物柴油中掺混四氢呋喃比例越大，有效热效率越低、有效燃油消耗率越高；负荷逐渐增大时，各燃料有效热效率先增大后稍微减小、有效燃油消耗率先减小后稍微增大。（4）生物柴油中掺混四氢呋喃比例越大，CO、HC、烟度、1,3-丁二烯、乙醛、苯的排放越低；但是T30燃料的CO、HC、烟度、1,3-丁二烯、乙醛这5种排放在0.13MPa负荷下比另外三种燃料都高。（5）生物柴油中掺混四氢呋喃比例越大，NO_X和CO₂的排放越高；但是在0.13MPa时，生物柴油中掺混四氢呋喃比例越大NO_X排放越低。

模拟结果表明，（1）在低温燃烧模式下，随着EGR率的增大，缸内压力曲线及放热率曲线峰值减小，缸内平均温度减小。（2）在低温燃烧模式下，随着EGR率的增大，NO排放减小，碳烟排放稍微减小。

关键词：生物柴油；四氢呋喃；燃烧；排放；EGR

Abstract

With the progress of society, the average income of people in Republic of China has increased deeply. However, the price of cars are falling. Chinese private car ownership is still growing rapidly. It is predicted that there will be more than 280 million cars in China before 2020. The energy crisis and environmental pollution has caused more and more prominent damage. Therefore, it will be a research hotspot to fig out replaceable fuels for traditional petrochemical diesel. Biodiesel is expected to be as an ideal fuel for traditional diesel, which is expected to replace the traditional fuel due to good renewability and cleanliness, but it also has the disadvantages of poor low temperature fluidity and atomization performance. Tetrahydrofuran is a kind of solvent with excellent performance. In this paper, the combustion and emission characteristics of Biodiesel Blended with tetrahydrofuran are studied from the perspective of fuel design.

First of all, tetrahydrofuran biodiesel Test fuels with mass fraction of 0%, 10%, 20% and 30% of tetrahydrofuran were prepared. The above four Test fuels were recorded as T0, T10, T20 and T30 respectively. On the engine bench, the oxidation and egresstion traits of Four Test fuels under different loads are studied through load characteristic test. In addition, the influence of EGR on the oxidation and egresstion of T20 heterogeneous-fuel under low temperature combustion mode is also studied by using the ese diesel module of AVL fire.

The results show that: (1) the larger the proportion of tetrahydrofuran is, the longer the ignition time it needs, the shorter the oxidation time is, but the combustion time of T30 is significantly prolonged under the load of 0.13mpa. If i t needs more time to load, the ignition will be expected to be shorter delay period and it will need more time to combust. (2) The larger the proportion of tetrahydrofuran in biodiesel, the higher the biggest pressure and energy transmit rate curve; the larger the load, the smaller the difference of biggest pressure e and the rate curve of energy transmit of the four fuels. (3) The higher the proportion of tetrahydrofuran in biodiesel, the lower the effective thermal efficiency and the higher the effectivity of fuel used ; when the load increases gradually, the effective thermal efficiency of each fuel increases first and declines slightly after that, and the effective fuel consumption decreases on the top and then increases slightly. (4) The higher the proportion of tetrahydrofuran in biodiesel, the lower the emissions of CO, HC, soot, 1,3-butadiene, acetaldehyde and benzene; however, the emissions of CO, HC, soot, 1,3-butadiene and acetaldehyde of T30 fuel are higher than those of the other three fuels at the load of 0.13mpa. (5) The higher the proportion of tetrahydrofuran in biodiesel, the higher the NOx and CO2 emissions; but at 0.13mpa, the more the tetrahydrofuran in biodiesel in this system, the less the NOx emissions will be.

The simulation results show that: (1) in the colder system, combustion mode, with the augment of EGR rate, the maximum of cylinder pressure and heat release rate curve decreases, and the average temperature in cylinder decreases. (2) In the low temperature combustion mode, while the climb of EGR rate, the no emission declined. At the same time, the soot emission declined slightly.

Key words: Biodiesel; Tetrahydrofuran; Combustion; Emission; EGR

目录

摘要 I

Abstract II

第1章 引言 1

1.1 研究背景及意义 1

1.1.1 能源安全和环境污染 1

1.1.2 排放法规 2

1.2 生物柴油的制备、性质及研究现状 3

1.2.1 生物柴油的制备和性质 3

1.2.2 生物柴油发动机存在的问题 4

1.2.3 生物柴油的研究现状 4

1.3 THF的制备方法、性能及研究现状 5

1.4 本文研究的主要内容 5

第2章 发动机台架试验设备介绍 7

2.1 试验装置 7

2.1.1 发动机台架和仪器设备 7

2.1.2 进排气系统 8

2.1.3 燃油供给系统 9

2.1.4 台架控制系统 9

2.1.5 数据采集系统 10

2.1.6 数据分析系统 11

2.2 尾气排放测量系统 11

2.3 试验燃料介绍 11

2.4 本章小结 12

第3章 负荷特性对THF-生物柴油混合燃料燃烧和排放的影响 13

3.1 实验方案 13

3.2 实验数据分析 13

3.2.1 燃烧特性分析 13

3.2.2 排放特性分析 17

第4章 生物柴油掺混THF混合燃料发动机的数值模拟 24

4.1 模型的建立与网格的划分 24

4.2 初始条件设置与计算模型选取 24

4.2.1 初始条件设置 24

4.2.2 计算模型选取 25

4.3 计算模型的验证 26

4.4 EGR率对THF-生物柴油在低温燃烧模式下的影响 26

4.4.1 燃烧特性分析 26

4.4.2 排放特性 28

4.5 本章小结 29

第5章 总结及工作展望 30

5.1 研究总结 30

5.2 工作展望 30

致谢 31

参考文献 32

引言

研究背景及意义

近年来，我国汽车保有量快速增长。图 1-1 是我国在2012-2018年的汽车保有量数据，截止到 2019年底，我国汽车保有量已经达到2.6亿辆，远高于之前的预期，据专家预测，2020年我国汽车保有量将超过2.80 亿辆。汽车产业和汽车制造技术的高速发展拉动了我国经济的发展，给我们的平时生活带来了诸多便利，但是，使用传统燃料汽车的快速增多也引发了能源安全和环境污染两个问题。