利用排氣廢熱之甲醇重組產出富氫氣體導入機車引擎之排汙特性探討

Study on the motorcycle engine fueled with hydrogen-rich gas produced from methanol by an exhaust heat recycling reformer

張常胤(Chang-Yin Chang)

指導教授 ： 洪榮芳

崑山科技大學/工程學院/機械工程研究所/碩士(2012年)

摘要

本研究利用引擎廢熱由甲醇重組產氫，並將產出的富氫氣體導入機車引擎，並利用氫氣的特性來改善汽油的燃燒效率、燃油消耗率與汙染排放，以達成提升能源的使用效率與減少汙染氣體排放的目標。
實驗主要可分成四個階段，第一階段主要針對原引擎的基礎數據實驗，將引擎的轉速由2000rpm至6500rpm、分成10筆的轉速參數；而節氣門開度的部分是由最小開度至最大開度、分成10筆節氣門開度的實驗參數。本階段實驗所得之數據可以了解原引擎之操作空燃比、噴油寬度與汙染排放的特性。而第二階段是使用高壓鋼瓶的氣體模擬產出之富氫氣體導入引擎，實驗參數包括模擬氣體的進料流率為5、10、15L/min三個進料參數，而模擬氣體的成分與比例為氫氣75Vol%、二氧化碳25Vol%。而引擎的實驗參數部分，轉速分成4000、5000、6000rpm三個轉速條件，而節氣門開度部分為1/3、2/3、3/3等三個開度來做為本階段的實驗參數。並將本階段實驗所得之數據與上階段所得之汙染排放與熱效率數據的改善程度作分析與探討。
第三階段是將重組器安裝至排氣管內，讓引擎所排放之廢氣餘熱用以提供重組器於重組過程中所需的能量，藉此達到廢熱回收的功效。而重組所使用的燃料為甲醇，使用部分氧化法來產出富氫氣體，並將富氫氣體進行分析。而本階段的實驗參數部分，O2/C比為0.1至0.5，用以找出較佳之重組轉化效率與熱效率；來做為下個實驗階段的重組器進料參數。而第四階段是採用上階段實驗所得之最佳的甲醇進料O2/C比，並搭配不同的進料流率所產出之富氫氣體導入引擎。而實驗所使用之重組器的進料參數，甲醇進料的O2/C比為0.3，而三個進料流率為3、6、9c.c/min等作為甲醇重組器的進料參數，而引擎的操作參數部分與模擬氣體導入實驗所用之操作參數相同。本階段實驗利用富氫氣體來提升稀油燃燒極限與改善燃燒效果以及燃油消耗率。
模擬氣體導入引擎的實驗結果發現，在相同空氣過剩率的情況下，相較於原車，使用模擬氣體導入引擎的CO與HC的排放、引擎熱效率與燃油消耗率皆有明顯的改善。但因導入模擬氣體的引擎可使用較為稀薄之空燃比操作範圍，改善了汽油的燃燒狀況使得NOx排放量有明顯上升的趨勢；而使用模擬氣體來導入引擎，使得容積效率下降，而造成引擎之輸出功率有下降的現象。而導入富氫氣體引擎的實驗結果與模擬氣體所得之結果大致相同，但因兩階段所導入引擎的氣體成分與比例以及減油的條件不同，而使實驗所得之數值會有所差異。

關鍵字

富氫引擎 ； 排氣管重組器 ； 機車引擎 ； 汙染排放 ； 熱效率

並列摘要

This study was to investigate the hydrogen-rich gas produced from methanol reforming by exhaust heat recovery on the exhaust emissions and performance of engine. Hydrogen-rich gas was introduced into the engine to improve the fuel consumption and exhaust emissions.
The experiments can be divided into four stages. The first phase of experiments is to derive the basic data of the original engine. The parameters studied included engine speed of 2000-6500rpm and the throttle openings. From the results, the original engine operating air-fuel ratio, fuel injection duration and exhaust emissions could be obtained. In the second stage, the simulation gas of premixed hydrogen-carbon dioxide was introduced into the engine, and a series of experiments were carried out. The feeding flow rate included 5, 10, and 15L/min with the molar fraction of 75%-hydrogen and 25%-carbon dioxide. The tested engine speeds were 4000rpm, 5000rpm and 6000rpm; and the throttle openings were 1/3, 2/3 and 3/3.
In the third stage, the reformer was installed in the exhaust pipe to utilize the waste heat of the engine to supply the energy required for methanol reforming, and partial oxidation was used to produce hydrogen-rich gas. The parameters, including O2/C (Oxygen/methanol molar) ratio, are experimented, and the best reforming parameters will be obtained. The best parameters obtained in the last stage would be applied to the fourth stage. That is, the best O2/C ratio of 0.3 with the flow rate of 3, 6, 9c.c/min for reforming was employed. The tested engine speeds were 4000rpm, 5000rpm and 6000rpm; and the throttle openings were 1/3, 2/3 and 3/3. The hydrogen-rich gas introduced into the engine was to improve the lean limit and fuel economy.
Among the series of experiments, many results were obtained. In the simulation gas experiments, it was found that CO, HC emissions, fuel consumption and thermal efficiency were improved as compared to the original engine. However, NOx emission increased, and the brake power decreased due to the reduction of volumetric efficiency. The trends by introducing the hydrogen-rich gas produced from the pipe reformer into the engine were similar to those of simulation gas experiments. However, there were differences between these two conditions because the compositions of the gases were not the same.

並列關鍵字

Hydrogen-rich gas engine ； Pipe reformer ； Motorcycle engine ； Pollution emissions ； Thermal efficiency

參考文獻

，崑山科技大學機械工程系，民國98年。

分析精選本，方嘉德編譯，滄海，2000。

[5] 陳宗男，“E2燃料應用於五期環保噴射機車汽油引擎性能影響之

[6] 翁碩偉，“排氣管重組器由乙醇產出負氫氣體為機車輔助燃料之引

[7] 葉順達，“以排氣廢熱來重組甲醇的富氫燃料引擎之性能改善與