The Experts below are selected from a list of 25902 Experts worldwide ranked by ideXlab platform
Aamir Farooq - One of the best experts on this subject based on the ideXlab platform.
-
ignition studies of n heptane iso Octane toluene blends
Combustion and Flame, 2016Co-Authors: Tamour Javed, Jihad Badra, Changyoul Lee, Mohammed Alabbad, Khalil Djebbi, Mohamed Beshir, Henry J Curran, Aamir FarooqAbstract:Ignition delay times of four ternary blends of n-heptane/iso-Octane/toluene, referred to as Toluene Primary Reference Fuels (TPRFs), have been measured in a high-pressure shock tube and in a rapid compression machine. The TPRFs were formulated to match the research Octane number (RON) and motor Octane number (MON) of two high-Octane gasolines and two prospective low-Octane naphtha fuels. The experiments were carried out over a wide range of temperatures (650–1250 K), at pressures of 10, 20 and 40 bar, and at equivalence ratios of 0.5 and 1.0. It was observed that the ignition delay times of these TPRFs exhibit negligible Octane dependence at high temperatures (T > 1000 K), weak Octane dependence at low temperatures (T < 700 K), and strong Octane dependence in the negative temperature coefficient (NTC) regime. A detailed chemical kinetic model was used to simulate and interpret the measured data. It was shown that the kinetic model requires general improvements to better predict low-temperature conditions and particularly requires improvements for high sensitivity (high toluene concentration) TPRF blends. These datasets will serve as important benchmark for future gasoline surrogate mechanism development and validation.
-
a methodology to relate Octane numbers of binary and ternary n heptane iso Octane and toluene mixtures with simulated ignition delay times
Fuel, 2015Co-Authors: Jihad Badra, Gautam Kalghatgi, Nehal Bokhumseen, Najood Mulla, Mani S Sarathy, Aamir Farooq, Patrick GaillardAbstract:Abstract Predicting Octane numbers (ON) of gasoline surrogate mixtures is of significant importance to the optimization and development of internal combustion (IC) engines. Most ON predictive tools utilize blending rules wherein measured Octane numbers are fitted using linear or non-linear mixture fractions on a volumetric or molar basis. In this work, the Octane numbers of various binary and ternary n-heptane/iso-Octane/toluene blends, referred to as toluene primary reference fuel (TPRF) mixtures, are correlated with a fundamental chemical kinetic parameter, specifically, homogeneous gas-phase fuel/air ignition delay time. Ignition delay times for stoichiometric fuel/air mixtures are calculated at various constant volume conditions (835 K and 20 atm, 825 K and 25 atm, 850 K and 50 atm (research Octane number RON-like) and 980 K and 45 atm (motor Octane number MON-like)), and for variable volume profiles calculated from cooperative fuel research (CFR) engine pressure and temperature simulations. Compression ratio (or ON) dependent variable volume profile ignition delay times are investigated as well. The constant volume RON-like ignition delay times correlation with RON was the best amongst the other studied conditions. The variable volume ignition delay times condition correlates better with MON than the ignition delay times at the other tested conditions. The best correlation is achieved when using compression ratio dependent variable volume profiles to calculate the ignition delay times. Most of the predicted research Octane numbers (RON) have uncertainties that are lower than the repeatability and reproducibility limits of the measurements. Motor Octane number (MON) correlation generally has larger uncertainties than that of RON.
Bradley T Zigler - One of the best experts on this subject based on the ideXlab platform.
-
effects of iso Octane ethanol blend ratios on the observance of negative temperature coefficient behavior within the ignition quality tester
Fuel, 2016Co-Authors: Gregory E Bogin, Eric Osecky, Matthew A Ratcliff, Jon Luecke, Bradley T ZiglerAbstract:Abstract An ignition delay study investigating the reduction in low temperature heat release (LTHR) and negative temperature coefficient (NTC) region with increasing ethanol concentration in binary blends of ethanol/isoOctane was conducted in the Ignition Quality Tester (IQT). The IQT is advantageous for studying multi-component fuels such as iso -Octane/ethanol which are difficult to study at lower temperatures covering the NTC region in traditional systems (e.g., shock tubes, rapid compression machines, etc.). The high Octane numbers and concomitant long ignition delay times of ethanol and iso -Octane are ideal for study in the IQT allowing the system to reach a quasi-homogeneous mixture; allowing the effect of fuel chemistry on ignition delay to be investigated with minimal impact from the fuel spray due to the relatively long ignition times. NTC behavior from iso -Octane/ethanol blends was observed for the first time using an IQT. Temperature sweeps of iso -Octane/ethanol volumetric blends (100/0, 90/10, 80/20, 50/50, and 0/100) were conducted from 623 to 993 K at 0.5, 1.0 and 1.5 MPa and global equivalence ratios ranging from 0.7 to 1.0. Ignition of the iso -Octane/ethanol blends in the IQT was also modeled using a 0-D homogeneous batch reactor model. Significant observations include: (1) NTC behavior was observed for ethanol/ iso -Octane fuel blends up to 20% ethanol. (2) Ethanol produced shorter ignition delay times than iso -Octane in the high temperature region. (3) The initial increase in ethanol from 0% to 10% had a lesser impact on ignition delay than increasing ethanol from 10% to 20%. (4) The 0-D model predicts that at 0.5 and 1.0 MPa ethanol produces the shortest ignition time in the high-temperature regime, as seen experimentally.
-
exploring the relationship between Octane sensitivity and heat of vaporization
SAE International Journal of Fuels and Lubricants, 2016Co-Authors: Scott C Sluder, Matthew A Ratcliff, Robert L Mccormick, James P Szybist, Bradley T ZiglerAbstract:The latent heat-of-vaporization (HoV) of blends of biofuel and hydrocarbon components into gasolines has recently experienced expanded interest because of the potential for increased HoV to increase fuel knock resistance in direct-injection (DI) engines. Several studies have been conducted, with some studies identifying an additional anti-knock benefit from HoV and others failing to arrive at the same conclusion. Consideration of these studies holistically shows that they can be grouped according to the level of fuel Octane sensitivity variation within their fuel matrices. When comparing fuels of different Octane sensitivity significant additional anti-knock benefits associated with HoV are sometimes observed. Studies that fix the Octane sensitivity find that HoV does not produce additional anti-knock benefit. New studies were performed at ORNL and NREL to further investigate the relationship between HoV and Octane sensitivity. Three fuels were formulated for the ORNL study with matched RON and Octane sensitivity, but with differing HoV. Experiments with these fuels in a 1.6-liter GTDI engine showed that the fuels exhibited very similar combustion phasing under knock-limited spark advance (KLSA) conditions. Fuels having a range of RON, Octane sensitivity, and HoV were tested at NREL in a single-cylinder GDI engine under conditions where Octane sensitivity has littlemore » effect on knock resistance. KLSA was found to be well correlated with RON. These results reinforce the concept that HoV anti-knock effects can be viewed as a contributor to Octane sensitivity. From this viewpoint, HoV effects manifest themselves as increases in Octane sensitivity.« less
Liming Xiang - One of the best experts on this subject based on the ideXlab platform.
-
ethanol blends in spark ignition engines ron Octane added value cooling effect compression ratio and potential engine efficiency gain
Applied Energy, 2017Co-Authors: Chongming Wang, Soheil Zeraatirezaei, Liming XiangAbstract:Identifying a sustainable, practical and low-emission energy supply for modern transportation has always been a challenge for energy and automotive researchers. While electrification of the vehicle powertrain is a promising long-term energy supply solution, bio-ethanol is currently playing an important role as a short- and mid-term solution for the popular spark ignition (SI) engine. The questions of how to use ethanol more effectively as an Octane booster, how much potential engine thermal efficiency gain can be achieved by using ethanol blends and what their impacts on the vehicle mileage range are have become highly relevant. In this paper, a critical review and discussion regarding these questions is provided. Firstly, studies regarding Octane rating and Octane index of gasoline fuels, and K value (a scaling factor for calculating Octane index) for various SI engines are reviewed. Then, a review of the research Octane number (RON), motor Octane number (MON) and Octane sensitivity for ethanol blends is reported. Three established models for predicting RON of ethanol blends are reviewed and compared. In addition, a simple RON prediction model proposed by the authors of this paper is provided. Parameters such as Octane value and Octane-added index (OAI) are proposed to describe the effectiveness of using ethanol as an Octane booster. It is found that there exits an optimised ethanol blend ratio that gives the maximum Octane value; and this optimised blend ratio is insensitive to the Octane rating of the base gasoline. Secondly, the charge cooling effect of ethanol blends and its corresponding equivalent Octane number are discussed and reviewed. Thirdly, engine thermal efficiency improvement due to increased compression ratios, which results from the Octane index gain achieved by using ethanol blends, is reviewed. Finally, a discussion about the impact of ethanol blends on the vehicle mileage range is presented. The lower heating value of ethanol is about 33% lower than that of typical gasoline, leading to a reduction in the mileage range of the vehicle, however, improved engine thermal efficiency achieved by using ethanol blends can partially, or even fully, offset the negative impact of the lower calorific value on the mileage range.
Jihad Badra - One of the best experts on this subject based on the ideXlab platform.
-
ignition studies of n heptane iso Octane toluene blends
Combustion and Flame, 2016Co-Authors: Tamour Javed, Jihad Badra, Changyoul Lee, Mohammed Alabbad, Khalil Djebbi, Mohamed Beshir, Henry J Curran, Aamir FarooqAbstract:Ignition delay times of four ternary blends of n-heptane/iso-Octane/toluene, referred to as Toluene Primary Reference Fuels (TPRFs), have been measured in a high-pressure shock tube and in a rapid compression machine. The TPRFs were formulated to match the research Octane number (RON) and motor Octane number (MON) of two high-Octane gasolines and two prospective low-Octane naphtha fuels. The experiments were carried out over a wide range of temperatures (650–1250 K), at pressures of 10, 20 and 40 bar, and at equivalence ratios of 0.5 and 1.0. It was observed that the ignition delay times of these TPRFs exhibit negligible Octane dependence at high temperatures (T > 1000 K), weak Octane dependence at low temperatures (T < 700 K), and strong Octane dependence in the negative temperature coefficient (NTC) regime. A detailed chemical kinetic model was used to simulate and interpret the measured data. It was shown that the kinetic model requires general improvements to better predict low-temperature conditions and particularly requires improvements for high sensitivity (high toluene concentration) TPRF blends. These datasets will serve as important benchmark for future gasoline surrogate mechanism development and validation.
-
a methodology to relate Octane numbers of binary and ternary n heptane iso Octane and toluene mixtures with simulated ignition delay times
Fuel, 2015Co-Authors: Jihad Badra, Gautam Kalghatgi, Nehal Bokhumseen, Najood Mulla, Mani S Sarathy, Aamir Farooq, Patrick GaillardAbstract:Abstract Predicting Octane numbers (ON) of gasoline surrogate mixtures is of significant importance to the optimization and development of internal combustion (IC) engines. Most ON predictive tools utilize blending rules wherein measured Octane numbers are fitted using linear or non-linear mixture fractions on a volumetric or molar basis. In this work, the Octane numbers of various binary and ternary n-heptane/iso-Octane/toluene blends, referred to as toluene primary reference fuel (TPRF) mixtures, are correlated with a fundamental chemical kinetic parameter, specifically, homogeneous gas-phase fuel/air ignition delay time. Ignition delay times for stoichiometric fuel/air mixtures are calculated at various constant volume conditions (835 K and 20 atm, 825 K and 25 atm, 850 K and 50 atm (research Octane number RON-like) and 980 K and 45 atm (motor Octane number MON-like)), and for variable volume profiles calculated from cooperative fuel research (CFR) engine pressure and temperature simulations. Compression ratio (or ON) dependent variable volume profile ignition delay times are investigated as well. The constant volume RON-like ignition delay times correlation with RON was the best amongst the other studied conditions. The variable volume ignition delay times condition correlates better with MON than the ignition delay times at the other tested conditions. The best correlation is achieved when using compression ratio dependent variable volume profiles to calculate the ignition delay times. Most of the predicted research Octane numbers (RON) have uncertainties that are lower than the repeatability and reproducibility limits of the measurements. Motor Octane number (MON) correlation generally has larger uncertainties than that of RON.
Gautam Kalghatgi - One of the best experts on this subject based on the ideXlab platform.
-
relating the Octane numbers of fuels to ignition delay times measured in an ignition quality tester iqt
Fuel, 2017Co-Authors: Nimal Naser, Gautam Kalghatgi, Seung Yeon Yang, Suk Ho ChungAbstract:Abstract A methodology for estimating the Octane index (OI), the research Octane number (RON) and the motor Octane number (MON) using ignition delay times from a constant volume combustion chamber with liquid fuel injection is proposed by adopting an ignition quality tester. A baseline data of ignition delay times were determined using an ignition quality tester at a charge pressure of 21.3 bar between 770 and 850 K and an equivalence ratio of 0.7 for various primary reference fuels (PRFs, mixtures of iso-Octane and n-heptane). Our methodology was developed using ignition delay times for toluene reference fuels (mixtures of toluene and n-heptane). A correlation between the OI and the ignition delay time at the initial charge temperature enabled the OI of non-PRFs to be predicted at specified temperatures. The methodology was validated using ignition delay times for toluene primary reference fuels (ternary mixtures of toluene, iso-Octane, and n-heptane), fuels for advanced combustion engines (FACE) gasolines, and certification gasolines. Using this methodology, the RON, the MON, and the Octane sensitivity were estimated in agreement with values obtained from standard test methods. A correlation between derived cetane number and RON is also provided.
-
a methodology to relate Octane numbers of binary and ternary n heptane iso Octane and toluene mixtures with simulated ignition delay times
Fuel, 2015Co-Authors: Jihad Badra, Gautam Kalghatgi, Nehal Bokhumseen, Najood Mulla, Mani S Sarathy, Aamir Farooq, Patrick GaillardAbstract:Abstract Predicting Octane numbers (ON) of gasoline surrogate mixtures is of significant importance to the optimization and development of internal combustion (IC) engines. Most ON predictive tools utilize blending rules wherein measured Octane numbers are fitted using linear or non-linear mixture fractions on a volumetric or molar basis. In this work, the Octane numbers of various binary and ternary n-heptane/iso-Octane/toluene blends, referred to as toluene primary reference fuel (TPRF) mixtures, are correlated with a fundamental chemical kinetic parameter, specifically, homogeneous gas-phase fuel/air ignition delay time. Ignition delay times for stoichiometric fuel/air mixtures are calculated at various constant volume conditions (835 K and 20 atm, 825 K and 25 atm, 850 K and 50 atm (research Octane number RON-like) and 980 K and 45 atm (motor Octane number MON-like)), and for variable volume profiles calculated from cooperative fuel research (CFR) engine pressure and temperature simulations. Compression ratio (or ON) dependent variable volume profile ignition delay times are investigated as well. The constant volume RON-like ignition delay times correlation with RON was the best amongst the other studied conditions. The variable volume ignition delay times condition correlates better with MON than the ignition delay times at the other tested conditions. The best correlation is achieved when using compression ratio dependent variable volume profiles to calculate the ignition delay times. Most of the predicted research Octane numbers (RON) have uncertainties that are lower than the repeatability and reproducibility limits of the measurements. Motor Octane number (MON) correlation generally has larger uncertainties than that of RON.
