期刊
FUEL
卷 185, 期 -, 页码 348-361出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.fuel.2016.07.103
关键词
Low temperature gasoline combustion; Negative valve overlap; Gasoline; Reforming; Photoionization mass spectrometry
资金
- U.S. Department of Energy, Office of Vehicle Technologies
- U.S. Department of Energy's National Nuclear Security Administration [DE-AC04-94AL85000]
- Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy [DE-AC02-05CH11231]
- Alberto Garcia
In-cylinder reforming of a gasoline pilot fuel injection during the negative valve overlap (NVO) period of an engine cycle can be used to alter the fuel-air mixture reactivity in low-temperature gasoline combustion (LTGC). In the present study, the impact of the NVO reformate on main-period engine performance was evaluated experimentally for four single-component surrogate gasoline fuels (iso-octane, n-heptane, ethanol, and 1-hexene) using a custom alternate-fire sequence. For each fuel, the NVO injection mass was held constant as the main-period injection mass was varied. The constant NVO injection mass allowed the NVO reformate product stream to be separately characterized in detail using photoionization mass spectrometry (PIMS). PIMS measurements were performed to characterize the NVO reformates of the four fuels used for main-period engine performance testing, as well as two additional fuels: cyclohexane and a toluene/n-heptane blend. All experiments were conducted using a direct-injection, single-cylinder research engine equipped with a custom dump valve apparatus used to perform bulk gas sampling at the end of the NVO period. A constant volume, adiabatic, single-zone reactor model with detailed chemical kinetic mechanisms was used to evaluate the reactivity of each NVO reformate compared to the unreformed parent fuel, the impact of specific species on reformate reactivity, and to examine the factors that influence main-period engine performance. The PIMS measurements and reactor model analysis indicated that all tested fuels (except n-heptane) exhibit increased reformate reactivity as compared to the unreacted parent fuel through production of more reactive species, namely acetylene, acetaldehyde, propene, and allene. Main-period engine performance was impacted by changes in reactivity from the reformate fraction of total fueling and compressed temperature (through the ratio of specific heats and differences in charge cooling from the main injection). iso-Octane was found to have the largest benefit in reactivity as the reformate fraction of total fueling increased. Alternatively, increases in reactivity for ethanol were primarily due to decreased charge cooling while reactivity increases for 1-hexene were dictated by increased ratio of specific heats. This paper demonstrates that NVO-generated reformate can improve main-period reactivity through both chemical and thermal effects, although significant NVO-period heat losses reduce total-cycle engine thermal efficiency. (C) 2016 Elsevier Ltd. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据