臺灣博碩士論文加值系統

摘 要

SI引擎燃燒室內燃料與空氣的混合過程對於能源效率與汙染物的產生影響很大。在冷啟動期間，燃料與空氣混合不完全，形成非均質之混合油氣造成不完全燃燒，燃料未完全燃燒而形成未燃碳氫化合物及一氧化碳造成汙染。提升引擎效能及降低排放汙染是現代汽車引擎工程師所要解決的問題。
本文實驗以量測SI引擎燃燒室內的燃料液滴粒徑變化，了解混合油氣的形成過程。實驗引擎由一可變速電氣馬達驅動，燃料的供給是以間歇噴射經由進氣口進入汽缸。根據Mie散射理論，在進氣及壓縮過程期間，液滴粒徑的量測是由光散射強度而得。利用雷射光學系統量測在不同運轉條件下的液滴粒徑變化。
在理論分析方面，模擬引擎在不同的運轉條件下燃料液滴的蒸發時程，利用正庚烷燃料計算以利驗證實驗值的準確性。
在不同的進氣溫度、進氣速度、燃料噴射量與噴射壓力對液滴的蒸發率會造成正面改變。由實驗與理論分析的結果可知趨勢是相同的。

ABSTRACT

Air-fuel mixture preparing process in combustion chamber of SI engine is important to energy efficiency and emission generation. Fuel and air mixing incompletely in cold-starting phase, the mixture in combustion chamber becomes heterogeneous and burns incompletely. The combustion products are unburned and incomplete combustion hydrocarbons produced. Improving energy efficiency and reducing exhaust emission are the task of modern automotive engineers.
An experimental study examined the fuel droplet behavior in the combustion chamber of SI engine to understand the mixture formation process. The engine was motored by a variable speed electric motor. Fuel was injected into the cylinder through the intake port intermittently. The fuel droplet diameter was determined at different operation conditions using laser optical system. The determination of fuel droplet diameter during the intake and compression stroke is based on the intensity of scattering light from droplet by Mie scattering theory.
A theoretical analysis simulates the evaporation history of fuel droplet at engine’s different operation conditions. Fuel n-heptane was simulated and checked during intake and compression process.
Different intake temperature, intake velocity, fuel injection amount and injection pressure affect the droplet evaporation rate positively. Experimental and numerical analysis results are equivalent.

目 錄
摘要…………………………………………………………………i
英文摘要……………………………………………………………ii
目錄…………………………………………………………………iii
圖目錄………………………………………………………………vi
表目錄………………………………………………………………ix
符號說明……………………………………………………………x

第一章、前言………………………………………………………1
　1.1研究動機…………………………………………………….1
　1.2文獻回顧…………………………………………………….1
　1.3研究方向…………………………………………………….3
第二章、液滴粒徑量測理論………………………………………4
　2.1光散射理論………………………………………………….4
　2.2光散射強度與粒徑參數關係………………………………11
　2.3 Mie散射理論之近似解............................13
　2.4 平均液滴粒徑的統計方法.........................15
第三章、燃料液滴粒徑量測………………………………………16
　3.1實驗設備…………………………………………………...16
　　3.1.1 引擎規格…..………………………………………..16
　　3.1.2燃料供給系統………………………………………..19
　　3.1.3光學量測系統………………………………………..24
　　3.1.4光學量測系統校正…………………………………..29
　3.2 實驗步驟………………………………………………….33
　　3.2.1光學系統校正………………………………………..33
　　3.2.2 實驗前準備………………………………………….33
3.2.3 實驗數據擷取……………………………………….34
第四章、燃料液滴蒸發之理論分析………………………………35
　4.1數值計算式………………………………………………...35
　4.2物性常數之推演…………………………………………...39
　4.3進氣條件與液滴粒徑關係………………………………...46
4.3.1進氣溫度與液滴粒徑關係…………………………..46
4.3.2進氣速度與液滴粒徑關係…………………………..46
　4.4噴射條件與液滴粒徑關係……………………………….48
4.4.1噴射壓力與液滴粒徑關係…………………………..48
4.4.2燃料噴射量與液滴粒徑關係………………………..49
第五章、結果與討論……………………………………………….51
5.1進氣溫度對燃料液滴蒸發過程的影響…………………...52
　5.2進氣速度對燃料液滴蒸發過程的影響…………………...52
　5.3燃料噴射壓力對液滴蒸發過程的影響…………………...52
　5.4燃料射入量對液滴蒸發過程的影響……………………...53
　5.5燃料噴射位置對液滴蒸發過程的影響…………………...53
　5.6 92無鉛汽油與正庚烷液滴粒徑之比較…………………..54
第六章、結論……………………………………………………….66
參考文獻 ……………………………………………………………68

參考文獻

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