E85燃料應用於機車汽油噴射引擎之性能效率及排氣污染研究

本研究將混合95無鉛汽油與乙醇所成之E85混合燃料使用於KYMCO之五期環保汽油噴射機車引擎，進行引擎動力平台測試。更換較大流量噴油嘴，且設定點火時間及噴油量修正於開迴路的模式下，調整燃油噴射時間使相對空燃比(λ)於0.8、0.9、1、1.1、1.2狀況，固定轉速於3000rpm、4000rpm、5000rpm及6000rpm，探討E85混合燃料對引擎制動單位比燃料消耗率、制動熱效率及廢氣排放之影響。實驗結果顯示，使用E85燃料時，CO濃度明顯減少﹔HC排放量因乙醇熱值較小所需噴油量增加及原廠設定參數（如點火正時、噴油正時）爲針對一般汽油引擎所設計等因素，使得E85燃料之HC排放濃度較爲偏高。在引擎輸出效率方面，於相同相對空燃比狀態，使用E85混合燃料較使用G95燃料之熱效率有明顯提升的趨勢。整體效果顯示使用E85燃料，在不改變引擎本體只更換噴油嘴狀態，其對CO排放污染減量及引擎效率有改善作用，且達到減少溫室氣體之功能。

關鍵字

E85混合燃料；相對空燃比λ ；燃油噴射時間

並列摘要

In order to reduce the impact of greenhouse gas on environment, searching the substitute for fossil fuels has been the main research topic in recent years. At the same time, applying the mixed fuel of ethanol and gasoline on a gasoline engine has become a trend. Research showed that using ethanol fuel not only has great achievements on the reduction of exhaust emission of gasoline engine, but also reduces the dependence on the fossil fuels. In this study an engine test is conducted by using the E85 mixed fuel on a fuel injection motorcycle engine. Under the mode of both ignition timing and injection timing controls set in open loop, the tests are run by changing the fuel injection duration, controlling the engine injection duration for relative air/fuel ratio (λ) at 0.8, 0.9, 1.0, 1.1, 1.2, and setting the speed at 3000 rmp, 4000 rmp, 5000 rpm, 6000 rpm, which correspond to the economic efficiency conditions, as experimental control variables to investigate the effect of E85 mixed fuel on engine performance and exhaust emission at different speed. The results show that using E85 fuel, CO emission is significantly reduced than that using G95 fuel. Although HC emission increases for engines running with E85 fuel due to the influences of increasing the amount of injection fuel to compensate the low calorific value of ethanol, and remaining the factory setting parameters (ignition timing, injection timing), the engine brake thermal efficiency is remarkably improved than that using G95 fuel. Without affecting the output power, the whole results show that using E85 fuel for reducing greenhouse gas in fuel injection SI engine with the same performance is available.