在密歇根州特拉弗斯城舉行的2016年CAR管理研討會（CAR Management Briefing Seminars）上，通用和本田的高層領(lǐng)導(dǎo)均表示，為了優(yōu)化現(xiàn)階段仍在研發(fā)之中的先進(jìn)內(nèi)燃機(jī)，提高美國汽油辛烷值勢在必行。在這兩位高管發(fā)表觀點之后，美國環(huán)保局交通和空氣質(zhì)量辦公室 （Office of Transportation and Air Quality for the U.S. EPA）主任Chris Grundler也給出了積極回應(yīng)，但并未作出最終結(jié)論。
在一場有關(guān)未來動力系統(tǒng)的嘉賓討論中，通用汽車全球推進(jìn)系統(tǒng)副總裁DanNicholson和本田汽車美國公司環(huán)境與能源戰(zhàn)略助理副總裁Robert Bienenfeld一致認(rèn)為，汽車行業(yè)必須推動提升美國汽油中的“最低”辛烷值。
“通過‘從石油到汽油’生產(chǎn)過程和對發(fā)動機(jī)效率的全面研究分析，推廣高辛烷值汽油是最經(jīng)濟(jì)的二氧化碳減排解決方案之一，”Nicholson告訴CAR大會中的嘉賓討論主持人Brett Smith，“我們在設(shè)計時，必須考慮燃油和發(fā)動機(jī)的匹配。如果完全撇開燃油不談，
Nicholson補(bǔ)充道，經(jīng)過專門設(shè)計的辛烷值更高的燃料“可以帶來很高的經(jīng)濟(jì)效益。”他說，美國能源部的一項分析證明，提高燃油辛烷值可以提高發(fā)動機(jī)的燃燒效率，并降低CO2排放。
本田的Bienenfeld也介紹說，高級渦輪增壓發(fā)動機(jī)在高負(fù)載設(shè)備及其他大型車輛應(yīng)用中，使用高辛烷值燃料頗具優(yōu)勢。他同時指出，增壓內(nèi)燃機(jī)車輛、混合動力車及燃料電池車都在本田未來的發(fā)展規(guī)劃之中。Nicholson則著重介紹了提高奧托循環(huán)壓縮比的趨勢，并表示他的工程團(tuán)隊也在研究米勒循環(huán)燃燒技術(shù)，以及“一路證明了自己的”渦輪增壓技術(shù)。
Nicholson表示，他很看好柴油發(fā)動機(jī)在美國的應(yīng)用潛力，“這里是全球少數(shù)幾個壓燃式發(fā)動機(jī)的增長市場之一。”
Bienenfeld表示，本田認(rèn)為“如果[現(xiàn)行]標(biāo)準(zhǔn)停留在2025年的水平”，那么采用48V混合動力技術(shù)將是一種非常經(jīng)濟(jì)實惠的選擇。
美國環(huán)保署官員Grundler在同一天晚些時候舉行會議中指出，環(huán)保署正在參與美國能源部開展的Optima項目，進(jìn)行有關(guān)未來燃油的相關(guān)研究，而且還專門設(shè)置了一個汽油辛烷值研究特別工作組。“燃油的變化并不在TAR（技術(shù)評估報告，即當(dāng)下CAFE規(guī)定中期審閱的一部分）的評估范圍之內(nèi)，”他示意，“只要不會增加溫室氣體排放”，就可以考慮在2025年后提高汽油燃料的辛烷值。
Optima項目旨在為一系列輕型、中型和重型車輛發(fā)動機(jī)開發(fā)最適合的燃料。美國橡樹嶺國家實驗室燃料、發(fā)動機(jī)與排放研究中心主任Wagner博士曾在SAE高效發(fā)動機(jī)研討會上宣布，Optima項目的目標(biāo)是在2030年前，將每輛汽車的平均汽油燃料消耗降低30％。這是汽油和乙醇生產(chǎn)商與汽車產(chǎn)業(yè)協(xié)同合作的成果。
美國能源部表示，如果可以實現(xiàn)Optima項目目標(biāo)，則可將全美的原油消耗降低45億桶，從而為消費者節(jié)約500億美元的燃油支出。
目前，2020年新型燃燒策略主要通過針對先進(jìn)米勒循環(huán)、稀燃和化學(xué)計量運行等燃燒技術(shù)的研究，從而實現(xiàn)50%甚至更高的峰值燃油效率。為了實現(xiàn)這一目標(biāo)，提高燃油的“最低”辛烷值至關(guān)重要。橡樹嶺國家實驗室的Wagner博士在SAE研討會上表示，一些多缸測試發(fā)動機(jī)的最高燃油效率可以突破55%。
馬自達(dá)Skyactiv項目旨在結(jié)合奧托燃燒循環(huán)和柴油機(jī)燃燒循環(huán)的各自優(yōu)勢，并最終取得最佳燃燒性能。該項目分G1、G2和G3三個階段分步推進(jìn)，并最終在G3階段實現(xiàn)：在λ為2.5時，取得18:1的壓縮比，即通過設(shè)定理想的HCCI（均質(zhì)充量壓縮點火）壓強(qiáng)和溫度，實現(xiàn)40%的熱效率提升。
在歐洲地區(qū)，與壓縮比在9.0到9.5:1的發(fā)動機(jī)使用的中檔95-RON汽油相比，分布廣泛的“超優(yōu)”102-RON汽油有助于為壓縮比高于11.5：1的發(fā)動機(jī)取得10%的燃油經(jīng)濟(jì)性提升。
作者：Lindsay Brooke
來源：SAE《汽車工程》雜志
翻譯：SAE 中國辦公室
GM, Honda execs agree: Higher octane gas needed to optimize ICE efficiency
Raising the octane level of pump gasoline in the U.S. is integral to optimizing advanced combustion engines now in development, said GM and Honda executives at the 2016 CAR Management Briefing Seminars in Traverse City, MI. Their comments prompted positive but non-committal comments from Chris Grundler, Director of the Office of Transportation and Air Quality for the U.S. EPA.
During a panel discussion on future powertrains, Dan Nicholson, VP of Global Propulsion Systems at GM, and Robert Bienenfeld, Assistant VP of Environment and Energy Strategy at American Honda, agreed that the industry must push for a higher fuel-octane “floor” in the U.S.
“Higher octane fuels are the cheapest CO2 reduction on a well-to-wheels analysis,” Nicholson told panel moderator Brett Smith of CAR. “Fuels and engines must be designed as a total system. It makes absolutely no sense to have fuel out of the mix” of engine-technology discussions, he asserted.
Nicholson added that higher-octane, purpose-designed fuels “can be delivered very cost effectively.” A U.S. Dept. of Energy analysis proved the benefit of higher octane levels in improving combustion efficiency and reducing engine-out CO2, he said.
Honda’s Bienenfeld pointed out the benefits of higher fuel octane levels on advanced turbocharged engines operating under high-load conditions and in large-vehicle applications. He noted that boosted gas engines, hybrids and fuel-cell vehicles are on the future-development path at Honda. Nicholson touted the trend toward higher Otto cycle compression ratios and said his engineering teams are looking at Miller cycle combustion, in conjunction with turbocharging, “earning its way into the portfolio.”
Nicholson also said he’s bullish on diesels in the U.S., “which is one of the few growth markets” for compression-ignition engines, he stated.
Regarding 48-volt hybrids, Honda considers them to be cost effective “if the [current] standards stop at 2025,” Bienenfeld said.
EPA’s Grundler, speaking at MBS later in the day, noted that his agency is participating in the U.S. Dept. of Energy’s Optima project studying future fuels and has a working group focused on gasoline octane. “Fuel changes are not part of the TAR [Technology Assessment Report, part of the Mid-term Review of the current CAFE regulations],” he said, while suggesting that higher octane levels be considered for after 2025 “as long as increasing octane levels do not increase greenhouse-gas emissions.”
The Optima project aims at developing co-optimized fuels with a range of new engines for light-, medium-, and heavy vehicle use. Announced at the SAE High-Efficiency Engines Symposium by Dr. Wagner, Director of the Fuels, Engines, and Emissions Research Center at Oak Ridge National Laboratory, Optima is targeting a 30% reduction in petroleum consumption, per vehicle, compared with a projected 2030 base case that uses today’s fuels. The initiative is a collaboration with producers of gasoline and ethanol and the auto industry.
If Optima achieves its goal, it could reduce petroleum consumption by 4.5 billion barrels and save consumers up to $50 billion, according to the DoE.
Raising the U.S. octane “floor” will be essential for new combustion strategies currently in development for the 2020s including advanced Miller cycle and those combining lean-burn and stoichiometric operation aimed at achieving peak efficiency levels of 50%. and above. ORNL’s Dr. Wagner told the SAE audience that some multi-cylinder dyno engines have pushed beyond 55%.
Mazda’s Skyactiv program is progressing through G1, G2, and G3 development stages toward a marriage of Otto and Diesel cycle characteristics. Engineers’ target for the G3 is 18:1 compression ratio at lambda 2.5—a 40% improvement in thermal efficiency by setting the ideal pressure and temperature for homogeneous charge compression ignition (HCCI).
In Europe, the 102-RON (research octane number) “super premium” gasoline that’s widely available helps deliver a 10% increase in fuel efficiency for engines running compression ratios above 11.5:1, compared with engines running 9.0 to 9.5:1 using the 95-RON fuel that’s marketed as the mid-grade gas in Europe.
Author: Lindsay Brooke
Source: SAE Automotive Enginnering Magazine
本田的Robert Bienenfeld（左）和通用汽車的Dan Nicholson在有關(guān)提高燃油辛烷值，從而優(yōu)化發(fā)動機(jī)能效方面的看法一致。