Fuels and Combustion
Type
Book ChapterAuthors
Johansson, Bengt
KAUST Department
Clean Combustion Research CenterMechanical Engineering Program
Physical Science and Engineering (PSE) Division
Date
2016-08-17Permanent link to this record
http://hdl.handle.net/10754/625548Metadata
Show full item recordAbstract
This chapter discusses the combustion processes and the link to the fuel properties that are suitable for them. It describes the basic three concepts, including spark ignition (SI) and compression ignition (CI), and homogeneous charge compression ignition (HCCI). The fuel used in a CI engine is vastly different from that in an SI engine. In an SI engine, the fuel should sustain high pressure and temperature without autoignition. Apart from the dominating SI and CI engines, it is also possible to operate with a type of combustion: autoignition. With HCCI, the fuel and air are fully premixed before combustion as in the SI engine, but combustion is started by the increased pressure and temperature during the compression stroke. Apart from the three combustion processes, there are also a few combined or intermediate concepts, such as Spark-Assisted Compression Ignition (SACI). Those concepts are discussed in terms of the requirements of fuel properties.Citation
Johansson B (2016) Fuels and Combustion. Biofuels from Lignocellulosic Biomass: 1–27. Available: http://dx.doi.org/10.1002/9783527685318.ch1.Publisher
WileyAdditional Links
http://onlinelibrary.wiley.com/doi/10.1002/9783527685318.ch1/summaryScopus Count
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Compression Ratio and Intake Air Temperature Effect on the Fuel Flexibility of Compression Ignition Engine(SAE International, 2019-09-10) [Conference Paper]The effect of compression ratio (CR) and intake air temperature on the combustion characteristics of fuels with different octane ratings were investigated on a single-cylinder heavy duty engine. The study focused on Primary Reference Fuels (PRFs) and commercial grade diesel with octane numbers ranging from 0 to 100. The engine was configured at a CR of 11.5:1, which is lower than typical heavy-duty compression ignition CI engines. This aims to compare the fuels' burning regime with recently reported measurements at CR17:1. Experiments were performed at different intake air temperatures of 20 to 80 °C and net indicated mean effective pressure (IMEPNet) of 5 to 20 bar. The injection rates have been characterized to determine the hydraulic delay of the injector and thus define the actual ignition delay time. At low loads, diesel-like fuels were found to burn in partially premixed combustion (PPC) mode whereas high octane fuels did not ignite. At high loads, fuels combustion becomes diffusion driven regardless of their RON or MON values. The effect of intake air temperature on the combustion characteristics depended on the combination of the octane ratings and the engine load. At high loads, fuels with low octane numbers were insensitive to the change of the intake air temperature. The ignition delay time was short enough to maintain a diffusion driven combustion. At lower loads, it is more challenging to reach conditions where the combustion characteristics are invariant regardless of the fuel's RON and MON values (Fuel Flexible). At the low tested compression ratio of 11.5:1, the extent of fuel flexibility is limited to only high loads (IMEPNet = 20 bar) whereas it is extended to intermediate loads (IMEPNet = 10 and 15 bar) at CR17:1.
