Benzene and n-Dodecane

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Autoignition Comparison of n-Dodecane/Benzene and n-Dodecane/ Toluene Blends in a Constant Volume Combustion Chamber Dong Han, Yaozong Duan, and Jiaqi Zhai Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.9b00451 • Publication Date (Web): 10 May 2019 Downloaded from http://pubs.acs.org on May 11, 2019

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Energy & Fuels

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Title: Autoignition Comparison of n-Dodecane/Benzene and n-Dodecane/Toluene Blends in a Constant Volume Combustion Chamber

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Authors: Dong Han, Yaozong Duan, Jiaqi Zhai

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Affiliations: Key Laboratory for Power Machinery and Engineering, Ministry of Education, Shanghai Jiao Tong University, Shanghai 200240, China

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Corresponding author’s contact information: Name: Dong Han Mailing Address: Institute of Internal Combustion Engine, 800 Dongchuan Road, Shanghai Jiao Tong University, Shanghai 200240, China Tel: +86 21 34206860 Fax: +86 21 34205553 Email: [email protected]

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Autoignition Comparison of n-Dodecane/Benzene and nDodecane/Toluene Blends in a Constant Volume Combustion Chamber Dong Han*, Yaozong Duan, Jiaqi Zhai Key Laboratory for Power Machinery and Engineering, Ministry of Education, Shanghai Jiao Tong University, Shanghai 200240, China Abstract Derived cetane numbers (DCN) of the n-dodecane/benzene and n-dodecane/toluene blends were measured using a constant-volume combustion chamber facility. The autoignition behaviors of the two sets of fuel blends, including ignition and combustion delay times, pressure traces, as well as the heat release rates at the DCN determination condition, i.e. 883 K ambient temperature and 20 bar ambient pressure, were also characterized. The results revealed that the n-dodecane/benzene blends have lower DCNs than those of the n-dodecane/toluene blends given the aromatics blending fractions. The two sets of fuel blends exhibit almost the same ignition delay time scales with low aromatics blending fractions, but the ignition delay of the dodecane/toluene blend becomes longer when the aromatics blending fraction rises to 60%. The combustion delays of the n-dodecane/toluene blends are slightly shorter at low aromatics blending fractions, and this difference becomes more apparent at a higher aromatics blending fraction. The n-dodecane/benzene blends exhibit later heat release starts than the n-dodecane/toluene blends given the aromatics blending fractions. With increased aromatics blending fraction, the heat release processes of the two sets of fuel blends change from single stage to two stage, and the differences in the heat release behaviors between the two sets of fuel blends increase. Keywords: Autoignition, n-Dodecane, Aromatics, Constant Volume Combustion Chamber

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Energy & Fuels

1 Introduction Autoignition propensity is an important property for the fuels used for diesel combustion engines, because the combustible mixture in diesel engines is prepared through direct fuel injection in the compression stroke and ignited by piston compression. Fuel autoignition propensity is particularly of importance in the advanced diesel combustion strategies [1], e.g. low temperature combustion [2, 3], premixed charge compression ignition [4, 5] and stratified charge combustion ignition [6, 7]. In these advanced combustion concepts that requires more uniform mixture distribution, the fuel and charge mixing quality highly depends on the length of the ignition induction period that is significantly influenced by fuel autoignition propensity. Therefore, researches have been conducted to investigate diesel autoignition characteristics and chemical kinetics [8, 9, 10] and the influential factors to control the fuel ignition delay times in engine cylinder [11, 12, 13]. However, practical diesel fuel is composed of thousands of components and their percentages are affected by the refinery process and production origin. The complexity of diesel composition poses difficulties in the accurate characterization of its autoignition features and combustion kinetics. Simplified surrogate fuels that could emulate some key combustion behaviors of practical fuels are thus considered in the fundamental combustion study instead of diesel fuels. Typical diesel surrogate fuels could be either a single fuel molecule [14, 15, 16] or multi-component mixtures [17, 18, 19]. The selection of single- or multi-component surrogate fuels depends on researchers’ specific needs. The single-component surrogate fuel has smaller chemical kinetic model size and is thus more suitable for the computational fluid dynamic (CFD) simulation in the combustion engines, while the multi-component mixtures could have better prediction results of the fundamental combustion performances of the practical fuels, as the multi-component surrogates are designed to cover more hydrocarbon classes in the practical fuels. Among the single-component surrogate fuels, n-heptane has been widely used in engine combustion study because of its similar cetane number with the practical diesel fuels [20, 21, 22]. However, the carbon chain length of nheptane is much shorter than the major components of the practical diesel fuels [23], and its higher volatility makes it unable to mimic the spray and atomization characteristics of diesel fuels in the reactive ambience as in the engine cylinders. Therefore, some researchers considered to use n-dodecane as the diesel surrogate in combustion studies, for its longer chain length and its comparable boiling features to the middle distillation range of diesel fuels [24, 25]. Besides n-alkanes, aromatics is another important chemical class in diesel fuels, as it does not only affect fuel autoignition propensity [26] but is also strongly related to the soot precursors formation [27]. Therefore, a single-ring aromatic molecule is generally selected as a constituent in the multi-component surrogate mixture for diesel fuels [28, 29]. Recently, some researchers [30, 31] constructed a binary-component diesel surrogate including ndodecane and alkyl-benzene. A detailed chemical mechanism for this surrogate mixture was developed and reduced to a skeletal size for engine combustion simulation by the 3


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authors. The skeletal mechanism of this n-dodecane/alkyl-benzene binary surrogate was further used to investigate the boundary condition effects on fuel spray and flame characteristics [32], as well as the engine combustion performances [33]. The above overview has shown that the blends of n-dodecane and simple aromatic molecules could be used as diesel fuel surrogates, and thus to characterize the autoignition performances, especially at engine-like conditions, of these mixtures could provide practical guidance for engine combustion system design. In this study, the autoignition characteristics of the blends of n-dodecane and two single-ring aromatics, benzene and toluene, were studied using a constant-volume combustion chamber (CVCC) facility. The derived cetane numbers (DCN) of the test blends with changed component fraction were measured according to the ASTM D7668 standard [34]. Additionally, some key combustion phasing parameters, including the ignition delay (ID) and combustion delay (CD), as well as the heat release rates at the DCN determination condition were characterized and compared for different fuel blends. 2 Methodology 2.1 Experimental Apparatus The experimental apparatus used in this study is a CVCC facility [35, 36, 37] designed to quantitatively determine the DCNs of liquid fuels. This facility comprises of a combustion chamber with heating elements, a fuel injection system consisting of a hydraulic pump, a pressure multiplier and an electronic diesel fuel injector, a close-loop cooling system for temperature control at the injector nozzle and pressure transducer, and a series of sensors for pressure and temperature measurement, e.g. ambient temperature and pressure prior to fuel injection, dynamic pressure change during fuel combustion, fuel injection pressure and the inner wall temperature of the combustion chamber. More information about this device can be found in the ASTM D7668 standard [34]. 2.2 Experimental Procedures The test condition for fuel DCNs determination using this facility is defined in the ASTM D7668 standard [34], which is also shown in Table 1. In this test, ID and CD in the fuel autoignition process are first obtained from the pressure traces. These two parameters are defined as the durations from the start of injection to two specific ending points, which are denoted based on the combustion pressure trace obtained by the dynamic pressure transducer. The start of injection here is estimated as the start of energizing, because according to the authors’ previous study [38], the interval between these two start instants only varied from 0.2 ms to 0.5 ms with changed injection pressure, which is much shorter than the ID and CD length in this study. The end point of ID period is defined as the moment at which the pressure increase in the combustion 4


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Energy & Fuels

chamber exceeds 0.2 bar. The end point of CD is defined as the time point when the pressure reaches the average of the initial pressure and the maximum pressure. The definitions of ID and CD are also depicted in Fig. 1. The calculation precisions of ID and CD are both 0.01 ms [34]. Table 1. Test conditions for DCN determination using CID 510 Target value 20 bar 883 K 2.5 ms 1000 bar

Ambient pressure Ambient temperature Injection duration Injection pressure

Tolerance limit ±0.2 bar ±0.2 K Not defined ±15 bar

The DCN test of each fuel was repeated for 15 times, and the consistence of the ID and CD values obtained from the 15 tests was examined. The abnormal values were removed and the remaining values were averaged for DCN calculation. DCN is calculated from the following multivariate conversion equation [34].

DCN  13.028  (5.3378 / ID)  (300.18 / CD) (1267.90 / CD 2 )  (3415.32 / CD3 )

(Eq.1)

The units of both ID and CD in this equation are millisecond.

Figure 1. Definition of ignition delay and combustion delay in autoignition 2.3 Heat Release Calculation From the measured pressure traces, we could derive the heat release processes using a simplified zero-dimension model. Several assumptions were made in this model. First, the working fluid was ideal gas and was uniformly distributed in the cylinder. Second, complete combustion was achieved and the working fluid reached thermodynamic equilibrium at all instants. Based on the above assumptions and thermodynamic equations, the heat release 5


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quantity Qi at the ith instant can be calculated as follows: (Eq.2)

Qi  ni  cvi  Ti  Qw

where ni is the mole quantity of working fluid, cvi is the average specific heat of the mixture, which is dependent on Ti, and Ti is the instantaneous temperature of the mixture in the chamber. Qw is the heat transfer loss to the chamber wall, which was estimated by the following heat convection equation: (Eq.3)

Qw  h  A  (Ti  Tw )

where A is the internal surface area, Tw is the wall temperature estimated as 773 K and h is natural convection coefficient estimated using the Woschni equation [39]. 1.4 Test Fuels The fuel blends in the CVCC tests were prepared using high purity (>98%) n-dodecane, benzene and toluene purchased from Sino Pharm. Some physical and chemical properties of the blending components are listed in Table 2. The volume percentage of benzene/toluene in fuel blends changed from 0% to 60%. In the following analysis, the test blends are denoted as D100, D80B20/D80T20, D60B40/D60T40 and D40B60/ D40T60, indicating benzene/toluene volume percentage is 0%, 20%, 40% and 60%, respectively. The corresponding mass percentages of benzene (toluene) in the blends are 0%, 22.6% (22.4%), 43.7% (43.5%), 63.6% (63.4%), respectively. The lower heating values of the tested fuel blends are 44.1 MJ/kg, 43.2 MJ/kg (43.3 MJ/kg), 42.4 MJ/kg (42.6 MJ/kg) and 41.6 MJ/kg (41.9 MJ/kg) with the benzene (toluene) volume percentage being 0%, 20%, 40% and 60%, respectively. As in the authors’ previous studies, changed fuel physical properties negligibly affect the fuel injection mass given the injection pressure and duration [40, 41], and we could therefore assume that the injection masses of different fuel blends in this test were constant. Table 2. Physical and chemical properties of blending components Property Lower heating value (MJ/kg) Molecular weight (kg/kmol) Boiling point (℃) Density (kg/m3) a Dynamic viscosity (10-4 Pa·s) b Cetane number c

n-Dodecane 44.2 170.3 216.3 750 13.6 74

a

Benzene 40.2 78.1 80 874 6.0 14.3

Toluene 40.6 92.1 110.6 867 5.6 6

Data measured at 25℃ and obtained from Reference [42] Data measured at 25℃, data of benzene and toluene obtained from Reference [42], data of n-dodecane obtained from Reference [43] c Data of n-dodecane, benzene and toluene obtained from References [44], [45] and [46], respectively b

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Energy & Fuels

3 Results and Discussion Figure 2 shows the pressure traces in the autoignition processes of the two sets of fuel blends. Three observations could be obtained from the comparison of these traces. First, the pressure traces of all the test fuels show a general trend, which is a slight pressure decrease at first due to the heat absorption of fuel vaporization, followed by a pressure rise due to fuel autoignition. Second, with increased aromatics blending fraction, the occurrence of pressure rise is retarded and the peak pressure is slightly elevated. Compared to n-dodecane, benzene and toluene are less reactive and their addition to ndodecane are expected to scavenge the active radicals produced by n-dodecane and reduce fuel autoignition propensity, and thus the induction period before fuel autoignition is extended. This may allow for more pre-mixture formation in the induction period and thus more completed combustion of the fuel and air charge. However, the reduced heat of combustion of fuels with increased aromatics blending may make the increase of the peak pressure insignificant. Third, as the aromatics blending fraction increases, the pressure rise gradually switches to a staged process, and there clearly exists an interval between the two pressure rise stages with the aromatics blending fraction of 60%, especially for the n-dodecane/benzene blend. As reported by Malewicki et al. [47], under the thermodynamic conditions presented in this study, the autoignition of n-dodecane is in the negative temperature coefficient regime, which results from the competition between the low temperature fuel oxidation and beta-scission reactions. The aromatics addition could alter this competition as they consume the active radicals and consequently change the fuel ignition behaviors. As a small amount of aromatics was added, e.g. 20%, a slightly extended induction time prior to rapid fuel oxidation was observed. However, further increased aromatic fraction might result in significantly reduced active radical concentration and boosted the radical scavenging effect, both of which contributed to the prolonged induction time and thus produced an evident two-stage pressure rise phenomenon. Due to the lower reactivity of benzene than toluene, n-dodecane/benzene blends exhibit more drastic two-stage autoignition behaviors than the n-dodecane/toluene blends.

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Figure 2. Pressure traces in the autoignition of the n-dodecane/aromatics blends: (a) ndodecane/benzene blends and (b) n-dodecane/toluene blends Figure 3 compares the peak pressures and peak pressure rise rates in the autoignition processes of the two sets of fuel blends. First, it is observed that the n-dodecane/toluene blends produce slightly higher peak pressures, in accordance with their slightly higher heat values. However, the overall variance in the peak pressure magnitudes with changed fuel compositions are negligible. Further, the n-dodecane/toluene blends have higher pressure rise rates than the n-dodecane/benzene blends, inferring the higher autoignition propensity of toluene. Compared to the low aromatic blending fractions, the difference in autoignition tendency between n-dodecane/toluene and ndodecane/benzene blends becomes more apparent at higher aromatic blending ratios, as indicated by the differences in both peak pressures and peak pressure rise rates. This is because with low aromatics blending, the high reactivity of n-dodecane plays a more important role in fuel autoignition, which produces higher peak pressure rise rates and the influences in the autoignition inhibition capacity of benzene and toluene are less significant. Finally, the peak pressure rise rate exhibits a non-monotonic trend with the aromatic fraction in fuel mixtures. The peak pressure raise rates firstly increase with benzene/toluene addition, but then decrease as the aromatic blending fraction exceeds 40%. The non-monotonic trend of the peak pressure rise rate versus increased aromatic fraction could be explained by the pressure trace features. With increased aromatic fractions, the pressure traces gradually switch from one-stage process to a two-stage process, which as such reduces the maximum pressure rise rate. As the ndodecane/benzene blends show more apparent two-stage pressure rise traces than ndodecane/toluene, the peak pressure rise rates of n-dodecane/benzene blends become lower than n-dodecane/toluene blends at higher aromatic blending fractions.

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Figure. 3 Comparison of the peak pressures and peak pressure rises rates of the ndodecane/benzene blends and n-dodecane/toluene blends: (a) peak pressures and (b) peak pressure rise rates Figure 4 shows the ignition and combustion delays of the fuel blends with different aromatics blending fractions. From Fig. 4a, we found that with low aromatics blending fractions, the two sets of fuel blends exhibit similar ignition delays given the blending fraction, but the ignition delays of the dodecane/toluene blends increase more rapidly when the aromatics blending fraction is higher than 40%. This is because that with low aromatics blending fractions, the ignition process is predominantly controlled by ndodecane, and the fuel effects of aromatics on ignition is limited. When the blending fraction of aromatics is higher than 40%, the contribution of aromatics becomes more influential, and thus the differences in the ignition delay times of the two sets of fuel blends are observed. However, this phenomenon seems to be inconsistent with the ignition delay measurements on a rapid compression machine (RCM) [48], in which Mittal and Sung observed that at the stoichiometric condition, the ignition delays of benzene were longer than those of toluene at temperatures from 950 K to 1100 K and a pressure of 45 bar. Also, the low-temperature oxidation study of n-decane/benzene and 9


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n-decane/toluene blends on a jet stirred reactor (JSR) by Herbinet et al. [49] indicated that the n-decane/toluene blends produced more active intermediates than the ndecane/benzene blends. This inconsistence could be explained by the difference in the autoignition regimes. In the RCM ignition and the JSR oxidation studies, the autoignition process of a homogeneous mixture is fully dominated by fuel chemistry, while in the spray autoignition process in a CVCC, the fuel ignition is simultaneously influenced by fuel physical and chemical properties. Further, the ignition instant in this study is defined as the time when the increase of chamber pressure exceeds 0.2 bar, which is highly sensitive to the fuel enthalpy of vaporization. As toluene has higher enthalpy of vaporization than benzene [50], it is reasonable that the n-dodecane/toluene blends exhibit longer ignition delays than the n-dodecane/benzene blends at higher aromatics blending fractions. Fig. 4b shows the combustion delays of two sets of fuel blends. Similar with the ignition delay comparison, the two sets of fuel blends also show close combustion delays as the aromatics blending fraction is below 60%, with the combustion delays of the ndodecane/benzene blends being slightly longer. Further, the combustion delay difference between the two sets of fuel blends becomes more apparent as the blending fraction of aromatics rises to 60%. According to the definition of combustion delay in this study, its length is simultaneously affected by fuel physics and chemistry. Zheng et al. [51] proposed to divide the induction period prior to combustion to physical and chemical delays to identify the contribution of fuel physics and chemistry to the length of the induction period. Here we take a similar strategy to separate the combustion delay period to two parts, i.e. the physics-dominant induction period and the chemistrydominant induction period. The ignition delay defined in this study is considered as the physics-dominant induction period, and the length difference between the ignition delay and combustion delay could be considered as the chemistry-dominant induction period. This is because the ignition delay in this study is defined as the interval between the start of injection and the time when the chamber pressure increase exceeds 0.2 bar, which is highly influenced by fuel vaporization and considered as the physicsdominated induction period. In contrast, the pressure rise mainly results from the rapid oxidation of fuel mixture, which is expected to be a chemistry-controlled process, thus the difference between ignition and combustion delays could be considered as the chemistry-dominated induction period. By comparing Fig. 4a and 4b, we can conclude that the n-dodecane/toluene blends show shorter chemistry-dominant induction periods, which is mainly attributed to the difference in fuel ignition chemistry of benzene and toluene. According to Mittal and Sung [48], the labile methyl C-H bond in toluene is more prone to break in the low-temperature autoignition regime. This is also consistent with the study by Seta et al. [52], in which they found that the reaction rate constant of toluene and OH radical is higher than that of benzene and OH radical at temperatures over 900 K.

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Energy & Fuels

Figure 4. Ignition and combustion delays of n-dodecane/benzene and ndodecane/toluene blends: (a) Ignition delay and (b) Combustion delay Based on the experimentally obtained ignition and combustion delay times, we could derive the DCNs of the two sets of fuel blends, which are shown in Fig. 5. The DCN of pure n-dodecane is 86.7, and the DCNs of fuel blends with 20%, 40% and 60% benzene (toluene) percentages are 56.7 (68.8), 43.5 (50.3) and 21.4 (31.2), respectively. The measured DCN of n-dodecane in this study is higher than that measured based on the ASTM D6890 standard, which is 74 as reported by Lilik and Boehman [44]. The large difference is possibly because that the two DCN determination standards, i.e. ASTM D7668 and ASTM D6890 standards, were reported to only possess good precision performances in the DCN ranges of 39-67 and 33-64, respectively, and outside these ranges the measurement variance becomes much higher. Besides the cetane number measurements of n-dodecane according to the aforementioned standards, we also noted that there are some reported cetane numbers of n-dodecane in the literature according to other determination methodologies, ranging from 78 to 88 [53, 54]. It is further observed that the DCNs of the n-dodecane/benzene blends are lower than those of the n-dodecane/toluene blends given a specific blending fraction. This is primarily because 11


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of the generally longer combustion delays of the n-dodecane/benzene blends, which are dominated by the fuel oxidation chemistry characteristics. Also, compared to the benzene/toluene blends, the DCNs of the n-dodecane/toluene blends decrease more linearly with increased aromatics blending fraction.

Figure 5. DCNs of the n-dodecane/benzene and n-dodecane/toluene blends Figure 6 shows the heat release rates of the two sets of fuel blends. The increased aromatics fraction retards the start of heat release, and this delay is particularly noticeable at the high blending fraction. It is also found that the maximum heat release rates increase with 20% benzene or toluene blending, but further increased aromatics fraction gradually reduces the maximum heat release rates of the fuel blends, with the heat release durations extended. The reduction of the maximum heat release rate and the extension of the heat release duration are particularly significant with the aromatics blending fraction being 60%. These observed phenomena in the heat release processes with changed aromatics fractions are in well agreement with the pressure rise behaviors as shown in Fig. 2.

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Energy & Fuels

Figure 6. Heat release rates of the n-dodecane/aromatics blends: (a) ndodecane/benzene blends and (b) n-dodecane/toluene blends Figure 7 compares the heat release rates of the two sets of fuel blends at specific blending fractions. When the aromatics blending fraction is 20%, the maximum heat release rate and the heat release duration of the two fuel blends are basically the same, but the start of heat release of the n-dodecane/benzene blend is later than that of the ndodecane/toluene blend. As the aromatics blending fraction rises to 40%, the ndodecane/toluene blend presents a higher maximum heat release rate and a shorter heat release duration than the n-dodecane/benzene blend. Also, the difference in the heat release phasing of the two fuel blends is enlarged compared to the 20% aromatics blending fraction. When the aromatics blending fraction reaches 60%, both of the fuel blends exhibit staged heat release behaviors, and the n-dodecane/benzene blend features longer interval between the two heat release stages. Further, the two fuel blends have similar start timing and heat release intensity in the first-stage heat release, but the second-stage heat release intensity of the n-dodecane/benzene blend is much lower than that of the n-dodecane/toluene blend, with the duration of the second-stage heat release being longer for the n-dodecane/benzene blend.

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Figure 7. Comparison of heat release rates of the n-dodecane/benzene blends and ndodecane/toluene blends given the aromatics blending fractions: (a) 20% aromatics blending fraction, (b) 40% aromatics blending fraction, (c) 60% aromatics blending fraction Conclusions In this study, the autoignition characteristics of the blends of n-dodecane and two single-ring aromatics, benzene and toluene, were studied using a CVCC facility. The DCNs of the fuel blends with changed component fraction were measured and the ignition and combustion delay times, pressure traces, as well as the heat release rates at the DCN determination conditions were characterized and compared for different fuel blends. Major conclusions are drawn as follows: 1) The ignition delay is primarily influenced by fuel physics, and the ignition delays of the two sets of fuel blends exhibit almost the same time scales with low aromatics blending fractions, but the ignition delay of the dodecane/toluene blend is longer when the aromatics blending fraction is over 40%. 14


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Energy & Fuels

2) The combustion delays of the n-dodecane/toluene blends are slightly shorter at low blending fractions of aromatics, but the difference in combustion delay between the two sets of fuel blends becomes more apparent as the blending fraction of aromatics rises to 60%. 3) The DCNs of the n-dodecane/benzene blends are lower than those of the ndodecane/toluene blends given the aromatics blending fraction. 4) The n-dodecane/benzene blend exhibits later heat release start and lower pressure rise rate than the n-dodecane/toluene blends given an aromatics blending fraction. With increased aromatics blending fraction, the heat release processes of the two sets of fuel blends switch from single stage to two stages, and the differences in the maximum heat release rate and heat release duration between the two sets of fuel blends increase. Acknowledgement This research work is supported by the National Natural Science Foundation of China (Grant Nos. 51776124 and 51861135303). Reference 1 Lu XC, Han D, Huang Z. Fuel design and management for the control of advanced compression-ignition combustion modes. Progress in Energy and Combustion Science 2011; 37 (6): 741-783. 2 Han D, Ickes AM, Bohac SV, et al. Premixed low-temperature combustion of blends of diesel and gasoline in a high speed compression ignition engine. Proceedings of the Combustion Institute 2011; 33 (2): 3039 - 3046. 3 Han D, Ickes AM, Assanis DN, et al. Attainment and load extension of highefficiency premixed low-temperature combustion with dieseline in a compression ignition engine. Energy Fuels 2010; 24(6): 3517-3525. 4 Bruckner C, Kyrtatos P, Boulouchos K. NOx emissions in direct injection diesel engines: Part 2: model performance for conventional, prolonged ignition delay, and premixed charge compression ignition operating conditions. International Journal of Engine Research 2018; 19 (5): 528-541. 5 Korkmaz M, Zweigel R, Jochim B, et al. Triple-injection strategy for model-based control of premixed charge compression ignition diesel engine combustion. International Journal of Engine Research 2018; 19 (2): 230-240. 6 Pal P, Keum SH, Im HG. Assessment of flamelet versus multi-zone combustion modeling approaches for stratified-charge compression ignition engines. International Journal of Engine Research 2016; 17 (3): 280-290. 7 Huang Z, Li ZZ, Zhang JY, et al. Active fuel design-A way to manage the right fuel for HCCI engines. Frontiers in Energy 2016; 10(1): 14-28. 8 Wang SX, Yu L, Wu ZY, et al. Gas-phase autoignition of diesel/gasoline blends over wide temperature and pressure in heated shock tube and rapid compression machine. Combustion and Flame 2019; 201: 264-275. 9 Haylett DR, Lappas PP, Davidson DF, et al. Application of an aerosol shock tube to the measurement of diesel ignition delay times. Proceedings of the Combustion Institute 15


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Energy & Fuels

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Benzene and n-Dodecane

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