论文总字数：21539字

摘 要

本文针对大气式中餐灶不能达到完全预混燃烧要求的缺点，对其引射器的结构进行了重新设计与优化：将中餐灶中的传统引射器设计为二级引射器，先使小部分空气在吸收室内吸引燃气，然后两种气体在混合管中混合均匀空气吸收室吸引燃烧所需剩余部分的空气。最终燃气与空气的比值在1:1.1左右。

本文主要根据质量守恒、能量守恒和动量守恒等公式构建了二级全预混引射器的理论计算模型并列出了其理论计算流程，同时计算出了功率为21kW、燃料为天然气的中餐灶全预混引射器的结构尺寸。

为了使引射器工作性能达到最优状态，本文还分析了一级空气系数、一级空气压力、截面比、燃气种类对全预混引射器结构参数及引射性能的影响，结果表明，在其他条件保持不变的情况下，引射器一级混合管出口压力随一级截面比的增大而先增加后减少，由此可以得出引射器存在最佳一级截面比；引射器二级截面比对引射器出口压力的影响趋势与一级截面比对一级混合管出口压力的影响趋势一致，同时也存在最佳二级截面比，但最佳一级截面比与最佳二级截面比的值并不相等。研究还表明引射器的最佳截面比与一级空气系数和燃气种类有关，而与一级空气压力无关；在最佳截面比下工作时，引射器的出口压力与引射器的一级空气系数和一级空气进口压力均有关：在一级空气系数一定的情况下，一级空气进口压力越大，引射器出口压力也就越大；在一级空气进口压力一定的情况下，一级空气系数越高，引射器出口压力越高。同时燃气种类不同引射器出口压力也会发生变化。

在功率为21kW，燃料为天然气，一级空气系数为0.05，空气喷嘴进口压力为3000Pa，燃气进口压力为2000Pa，喷嘴进口直径为15mm的情况下，最佳一级截面比为15，最佳二级截面比为130；燃料为液化石油气时，最佳一级截面比为10，最佳二级截面比为190 。根据以上的结论，将所设计引射器的结构进行了优化，从而得出了功率为21kW、燃料分别为天然气、液化石油气的燃气灶引射器的最佳结构尺寸。

关键词: 全预混引射器 天然气 理论建模 结构优化

Design and Performance Analysis of Full Premixed

Chinese Cooker

ABSTRACT

The structure of the ejector optimized for the shortcomings of the atmospheric cooking stove, which is can not achieve the requirement of complete premixed combustion. The traditional ejector in the stove is redesigned as two-stage ejector. A few part of the air attracts gas in the absorption chamber, then the two gases mix in the mixing tube, and then use the mixed gas to attract the air which is needed in the process of combustion. Finally the ratio of gas to air ratio is about 1: 1.1.

Based on the formula of mass conservation, energy conservation and momentum conservation, this paper constructs the theoretical calculation model of the two-stage premixed injector and lists its theoretical calculation process. At the same time, the paper gets the structure size of the eccentric ejector whose energy is 21kW and gas is natural gas.

In order to optimize the working performance of the ejector, the influence of the first-order air pressure, the first-order air pressure, the cross-sectional ratio and the gas type on the structural parameters as well as the ejecting performance of the complete premixed ejector is analyzed. In the case of other conditions remain unchanged, the ejector first-order mixing pipe outlet pressure increases first and then decreases with the increase of the cross-section ratio. At the same time it can be concluded that the ejector has the best first- order cross-sectional area ratio. The influence of the secondary section of the ejector on the outlet pressure of the ejector is the same as that of the primary section, and there is the optimal secondary cross-sectional ratio which is not equal to the value of the optimal secondary cross-sectional area ratio. The study also shows that the optimal cross-sectional ratio of the ejector is related to the primary air coefficient and the type of gas, but it is independent of the primary air pressure. At the optimum cross-sectional ratio, the outlet pressure of the ejector is related to the primary air coefficient and the first level of air inlet pressure. In the case of a certain air factor, the greater the pressure of an air inlet is, the greater the pressure of the ejector outlet is. In the case of a certain level of air inlet pressure, the higher the primary air coefficient is, the higher the ejector outlet pressure is. Finally the ejectors for different type of fuel have different outlet pressure.

In the case of a power of 21 kW, the fuel of natural gas, the primary air coefficient of 0.05, the air nozzle inlet pressure of 3000 Pa, the gas inlet pressure of 2000 Pa, and the nozzle inlet diameter of 15 mm, the optimum first section ratio is 15 and the Sectional ratio 130，but in the case of fuel of liquefied petroleum gas, the best first-order cross-section ratio is 10 and the best secondary section ratio is 190. According to the above conclusions, the structure of the designed ejector is optimized, and the optimal structure size of the gas burner with the power of 21kW and the natural gas and liquefied petroleum gas is obtained.

Key Words: Premixed ejector; Nature gas; Theoretical model; optimal structure

符号表

下标

目录

摘 要 I

ABSTRACT III

符号表 V

第1章 绪论 1

1.1背景 1

1.2引射器的状况 1

1.2.1引射器的工作过程 1

1.2.2引射器的分类 2

1.3国内外研究现状 3

1.4本课题研究概况 4

1.5小结 4

第2章 全预混引射器结构 6

2.1结构组成及作用 6

2.2工作原理 6

2.3设计参数 7

2.4性能要求 8

2.5小结 8

第3章 理论计算模型 9

3.1喷嘴 9

3.2 混合管 10

3.3吸收室 11

3.4扩压管 11

3.5引射器理论计算流程 12

3.6小结 14

第4章21kW全预混引射器设计与分析 15

4.1燃烧计算 15

4.2 引射器的理论计算 16

4.2.1一级喷嘴计算 16

4.2.2一级混合管计算 16

4.2.3二级喷嘴与混合管计算 16

4.2.4扩压管计算 17

4.3性能分析 17

4.3.1不同一级空气压力与截面比对混合管出口压升的影响 17

4.3.2一级引射系数与一级截面比对一级混合管出口压力的影响 18

4.3.3二级截面比与一级空气压力对引射器出口压力的影响 19

4.3.4二级截面比与一级引射系数多引射器出口压力的影响 20

4.3.5不同一级空气系数与一级空气压力对一级引射器出口压力的影响 20

4.3.6燃气种类对引射器结构的影响 21

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