Predicting Fuel Performance for Future HCCI Engines

Investigation of the LTC fuel performance index for oxygenated reference fuel blends

“…Later, Shibata and Urushihara [15] developed three HCCI fuel indices, including the relative HCCI index that combines MON with information about the fuel composition. However, as Rapp et al [22] recently showed in a study of the performance of various fuels in a Cooperative Fuel Research (CFR) engine operating in HCCI mode, neither of the octane or relative HCCI indices can predict the autoignition behavior for a wide range of fuels. In particular, the correlations for both indices poorly predict the behavior of gasoline blends with naphthenes, aromatics, and ethanol.…”

“…These values are determined by comparing the knocking characteristics under standardized conditions to those of a binary mixture of the PRFs n-heptane and 2,2,4-trimethylpentane (isooctane), where 0 and 100 correspond to the volume percentage of n-heptane and isooctane, respectively. However, various studies showed that octane rating does not adequately predict autoignition in HCCI engines [14,15,22,23], due to the fact that real fuels consist of more complex mixtures of fuel components compared to the PRFs.…”

“…While strategies to use typical gasoline and diesel fuels in HCCI engines have been investigated [7,9], another option is to find new fuels or fuel blends that may offer more attractive performance. Various groups studied the operating ranges of different fuels in HCCI engines with the goal of identifying attractive species or mixtures [10][11][12][13][14][15][16][17][18][19][20][21][22][23]. The fuels studied include-but are not limited to-real fuels such as gasoline [10,11,17,[20][21][22], diesel [10,18,20], and Jet B [18].…”

“…Various groups studied the operating ranges of different fuels in HCCI engines with the goal of identifying attractive species or mixtures [10][11][12][13][14][15][16][17][18][19][20][21][22][23]. The fuels studied include-but are not limited to-real fuels such as gasoline [10,11,17,[20][21][22], diesel [10,18,20], and Jet B [18]. In addition, numerous studies focused on neat fuels and mixtures of such, including n-butane [11], neat and blends of the primary reference fuels (PRFs) n-heptane and isooctane [10-13, 16, 17, 19, 22, 23], and mixtures of the PRFs with toluene [22,23] and ethanol [17,22,23] both individually and together [23].…”

“…The fuels studied include-but are not limited to-real fuels such as gasoline [10,11,17,[20][21][22], diesel [10,18,20], and Jet B [18]. In addition, numerous studies focused on neat fuels and mixtures of such, including n-butane [11], neat and blends of the primary reference fuels (PRFs) n-heptane and isooctane [10-13, 16, 17, 19, 22, 23], and mixtures of the PRFs with toluene [22,23] and ethanol [17,22,23] both individually and together [23]. Other groups investigated the behavior of alcohols in HCCI engines, including neat butanol [20] and ethanol [20,[24][25][26]; wet ethanol also received significant attention as a neat fuel due to the potential for increased overall energy efficiency by avoiding or reducing distillation and dehydration [27][28][29].…”