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Title: Tailoring Charge Reactivity Using In-Cylinder Generated Reformate for Gasoline Compression Ignition Strategies

In-cylinder reforming of injected fuel during a negative valve overlap (NVO) recompression period can be used to optimize main-cycle combustion phasing for low-load low-temperature gasoline combustion (LTGC). The objective of this work is to examine the effects of reformate composition on main-cycle engine performance. An alternate-fire sequence was used to generate a common exhaust temperature and composition boundary condition for a cycle-of-interest, with performance metrics measured for these custom cycles. NVO reformate was also separately collected using a dump valve apparatus and characterized by both gas chromatography and photoionization mass spectroscopy. To facilitate gas sample analysis, sampling experiments were conducted using a five-component gasoline surrogate (isooctane, n-heptane, ethanol, 1-hexene, and toluene) that matched the molecular composition, 50% boiling point, and ignition characteristics of the research gasoline. For the gasoline, it was found that an advance of the NVO start-of-injection (SOI) led to a corresponding advance in main-period combustion phasing as the combination of longer residence times and lower amounts of liquid spray piston impingement led to a greater degree of fuel decomposition. The effect was more pronounced as the fraction of total fuel injected in the NVO period increased. Main-period combustion phasing was also found to advance as the main-periodmore » fueling decreased. Slower kinetics for leaner mixtures were offset by a combination of increased bulk-gas temperature from higher charge specific heat ratios and increased fuel reactivity due to higher charge reformate fractions.« less
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [4]
  1. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
  2. Tula Technology, Inc., San Jose, CA (United States(
  3. Univ. of Minnesota, Minneapolis, MN (United States)
  4. Braunschweig Univ. of Technology (Germany)
Publication Date:
Report Number(s):
SAND2018-9577J
Journal ID: ISSN 0742-4795; 667499
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Journal of Engineering for Gas Turbines and Power
Additional Journal Information:
Journal Volume: 139; Journal Issue: 12; Journal ID: ISSN 0742-4795
Publisher:
ASME
Research Org:
Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING
OSTI Identifier:
1469636

Ekoto, Isaac W., Wolk, Benjamin M., Northrop, William F., Hansen, Nils, and Moshammer, Kai. Tailoring Charge Reactivity Using In-Cylinder Generated Reformate for Gasoline Compression Ignition Strategies. United States: N. p., Web. doi:10.1115/1.4037207.
Ekoto, Isaac W., Wolk, Benjamin M., Northrop, William F., Hansen, Nils, & Moshammer, Kai. Tailoring Charge Reactivity Using In-Cylinder Generated Reformate for Gasoline Compression Ignition Strategies. United States. doi:10.1115/1.4037207.
Ekoto, Isaac W., Wolk, Benjamin M., Northrop, William F., Hansen, Nils, and Moshammer, Kai. 2017. "Tailoring Charge Reactivity Using In-Cylinder Generated Reformate for Gasoline Compression Ignition Strategies". United States. doi:10.1115/1.4037207. https://www.osti.gov/servlets/purl/1469636.
@article{osti_1469636,
title = {Tailoring Charge Reactivity Using In-Cylinder Generated Reformate for Gasoline Compression Ignition Strategies},
author = {Ekoto, Isaac W. and Wolk, Benjamin M. and Northrop, William F. and Hansen, Nils and Moshammer, Kai},
abstractNote = {In-cylinder reforming of injected fuel during a negative valve overlap (NVO) recompression period can be used to optimize main-cycle combustion phasing for low-load low-temperature gasoline combustion (LTGC). The objective of this work is to examine the effects of reformate composition on main-cycle engine performance. An alternate-fire sequence was used to generate a common exhaust temperature and composition boundary condition for a cycle-of-interest, with performance metrics measured for these custom cycles. NVO reformate was also separately collected using a dump valve apparatus and characterized by both gas chromatography and photoionization mass spectroscopy. To facilitate gas sample analysis, sampling experiments were conducted using a five-component gasoline surrogate (isooctane, n-heptane, ethanol, 1-hexene, and toluene) that matched the molecular composition, 50% boiling point, and ignition characteristics of the research gasoline. For the gasoline, it was found that an advance of the NVO start-of-injection (SOI) led to a corresponding advance in main-period combustion phasing as the combination of longer residence times and lower amounts of liquid spray piston impingement led to a greater degree of fuel decomposition. The effect was more pronounced as the fraction of total fuel injected in the NVO period increased. Main-period combustion phasing was also found to advance as the main-period fueling decreased. Slower kinetics for leaner mixtures were offset by a combination of increased bulk-gas temperature from higher charge specific heat ratios and increased fuel reactivity due to higher charge reformate fractions.},
doi = {10.1115/1.4037207},
journal = {Journal of Engineering for Gas Turbines and Power},
number = 12,
volume = 139,
place = {United States},
year = {2017},
month = {8}
}