An Investigation on Sensitivity of Ignition Delay and Activation Energy in Diesel Combustion

2014 ◽  
Author(s):  
Umashankar Joshi ◽  
Ziliang Zheng ◽  
Amit Shrestha ◽  
Naeim Henein ◽  
Eric Sattler
Keyword(s):  
Activation Energy ◽  
Ignition Delay ◽  
Cetane Number ◽  
Ignition Process ◽  
Start Of Injection ◽  
Auto Ignition ◽  
Time Period ◽  
Ignition Quality ◽  
Ignition Quality Tester ◽  
Start Of Combustion

The auto-ignition process plays a major role in the combustion, performance, fuel economy and emission in diesel engines. The auto-ignition quality of different fuels has been rated by its cetane number (CN) determined in the CFR engine, according to ASTM D613. More recently, the Ignition Quality Tester (IQT), a constant volume vessel, has been used to determine the derived cetane number (DCN) to avoid the elaborate, time consuming and costly engine tests, according to ASTM D6890. The ignition delay period in these two standard tests and many investigations has been considered to be the time period between start of injection (SOI) and start of combustion (SOC). The ignition delay (ID) values determined in different investigations can vary due to differences in instrumentation and definitions. This paper examines the different definitions and the parameters that effect ID period. In addition the activation energy dependence on the ID definition is investigated. Furthermore, results of an experimental investigation in a single-cylinder research diesel engine will be presented while the charge density is kept constant during the ID period. The global activation energy is determined and its sensitivity to the charge temperature is examined.

An Investigation on Sensitivity of Ignition Delay and Activation Energy in Diesel Combustion

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Umashankar Joshi ◽  
Ziliang Zheng ◽  
Amit Shrestha ◽  
Naeim Henein ◽  
Eric Sattler
Keyword(s):  
Activation Energy ◽  
Ignition Delay ◽  
Cetane Number ◽  
Ignition Process ◽  
Start Of Injection ◽  
Auto Ignition ◽  
Time Period ◽  
Ignition Quality ◽  
Ignition Quality Tester ◽  
Start Of Combustion

The auto-ignition process plays a major role in the combustion, performance, fuel economy, and emission in diesel engines. The auto-ignition quality of different fuels has been rated by its cetane number (CN) determined in the cooperative fuel research engine, according to ASTM D613. More recently, the ignition quality tester (IQT), a constant volume vessel, has been used to determine the derived cetane number (DCN) to avoid the elaborate, time consuming, and costly engine tests, according to ASTM D6890. The ignition delay (ID) period in these two standard tests and many investigations has been considered to be the time period between start of injection (SOI) and start of combustion (SOC). The ID values determined in different investigations can vary due to differences in instrumentation and definitions. This paper examines the different definitions and the parameters that effect ID period. In addition, the activation energy dependence on the ID definition is investigated. Furthermore, results of an experimental investigation in a single-cylinder research diesel engine will be presented, while the charge density is kept constant during the ID period. The global activation energy is determined and its sensitivity to the charge temperature is examined.

Investigation of Physical and Chemical Delay Periods of Different Fuels in the Ignition Quality Tester

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Ziliang Zheng ◽  
Tamer Badawy ◽  
Naeim Henein ◽  
Eric Sattler
Keyword(s):  
Activation Energy ◽  
Cetane Number ◽  
Delay Period ◽  
Ignition Process ◽  
Ultra Low Sulfur Diesel ◽  
Air Temperatures ◽  
Auto Ignition ◽  
Ignition Quality ◽  
Ignition Quality Tester ◽  
Physical And Chemical

This paper investigates the physical and chemical ignition delay (ID) periods in the constant volume combustion chamber of the Ignition Quality Tester (IQT). IQT was used to determine the derived cetane number (DCN) according to ASTM D6890-10a standards. The fuels tested were ultra low sulfur diesel (ULSD), jet propellant-8 (JP-8), and two synthetic fuels of Sasol IPK and F-T SPK (S-8). A comparison was made between the DCN and cetane number (CN) determined according to ASTM-D613 standards. Tests were conducted under steady state conditions at a constant pressure of 21 bars and various air temperatures ranging from 778 K to 848 K. The rate of heat release (RHR) was calculated from the measured pressure trace, and a detailed analysis of the RHR trace was made particularly for the auto-ignition process. Tests were conducted to determine the physical and chemical delay periods by comparing results obtained from two tests. In the first test, the fuel was injected into air according to ASTM standards. In the second test, the fuel was injected into nitrogen. The point at which the two resultant pressure traces separated was considered to be the end of the physical delay period. The effects of the charge temperature on the total ID as defined in ASTM D6890-10a standards, as well as on the physical and chemical delays, were determined. It was noticed that the physical delay represented a significant part of the total ID over all the air temperatures covered in this investigation. Arrhenius plots were developed to determine the apparent activation energy for each fuel using different IDs. The first was based on the total ID measured according to ASTM standards. The second was the chemical delay determined in this investigation. The activation energy calculated from the total ID showed higher values for lower CN fuels except Sasol IPK. The activation energy calculated from the chemical delay period showed consistency in the increase of the activation energy with the drop in CN including Sasol IPK. The difference between the two findings could be explained by examining the sensitivity of the physical delay period of different fuels to the change in air temperature.

Effect of Cetane Improver on Autoignition Characteristics of Low Cetane Sasol IPK Using Ignition Quality Tester1

2014 ◽  
Vol 136 (8) ◽  
Author(s):  
Ziliang Zheng ◽  
Tamer Badawy ◽  
Naeim Henein ◽  
Eric Sattler ◽  
Nicholas Johnson
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Fuel Injection ◽  
Cetane Number ◽  
Start Of Injection ◽  
Constant Charge Density ◽  
Ignition Quality ◽  
Rate Of Heat Release ◽  
Ignition Quality Tester ◽  
Physical And Chemical

This paper investigates the effect of a cetane improver on the autoignition characteristics of Sasol IPK in the combustion chamber of the ignition quality tester (IQT). The fuel tested was Sasol IPK with a derived cetane number (DCN) of 31, treated with different percentages of Lubrizol 8090 cetane improver ranging from 0.1 to 0.4%. Tests were conducted under steady state conditions at a constant charging pressure of 21 bar. The charge air temperature before fuel injection varied from 778 to 848 K. Accordingly, all the tests were conducted under a constant charge density. The rate of heat release was calculated and analyzed in detail, particularly during the autoignition period. In addition, the physical and chemical delay periods were determined by comparing the results of two tests. The first was conducted with fuel injection into air according to ASTM standards where combustion occurred. In the second test, the fuel was injected into the chamber charged with nitrogen. The physical delay is defined as the period of time from start of injection (SOI) to point of inflection (POI), and the chemical delay is defined as the period of time from POI to start of combustion (SOC). Both the physical and chemical delay periods were determined under different charge temperatures. The cetane improver was found to have an effect only on the chemical ID period. In addition, the effect of the cetane improver on the apparent activation energy of the global combustion reactions was determined. The results showed a linear drop in the apparent activation energy with the increase in the percentage of the cetane improver. Moreover, the low temperature (LT) regimes were investigated and found to be presented in base fuel, as well as cetane improver treated fuels.

Effect of Cetane Improver on Autoignition Characteristics of Low Cetane Sasol IPK Using Ignition Quality Tester (IQT)

2013 ◽  
Author(s):  
Ziliang Zheng ◽  
Tamer Badawy ◽  
Naeim Henein ◽  
Eric Sattler ◽  
Nicholas Johnson
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Fuel Injection ◽  
Cetane Number ◽  
Start Of Injection ◽  
Constant Charge Density ◽  
Ignition Quality ◽  
Rate Of Heat Release ◽  
Ignition Quality Tester ◽  
Physical And Chemical

This paper investigates the effect of a cetane improver on the autoignition characteristics of Sasol IPK in the combustion chamber of the Ignition Quality Tester (IQT). The fuel tested was Sasol IPK with a Derived Cetane Number (DCN) of 31, treated with different percentages of Lubrizol 8090 cetane improver ranging from 0.1% to 0.4%. Tests were conducted under steady state conditions at a constant charging pressure of 21 bar. The charge air temperature before fuel injection varied from 778 to 848 K. Accordingly, all the tests were conducted under a constant charge density. The rate of heat release was calculated and analyzed in details, particularly during the autoignition period. In addition, the physical and chemical delay periods were determined by comparing the results of two tests. The first was conducted with fuel injection into air according to ASTM standards where combustion occurred. In the second test, the fuel was injected into the chamber charged with nitrogen. The physical delay is defined as the period of time from start of injection (SOI) to point of inflection (POI), and the chemical delay is defined as the period of time from POI to start of combustion (SOC). Both the physical and chemical delay periods were determined under different charge temperatures. The cetane improver was found to have an effect only on the chemical ID period. In addition, the effect of the cetane improver on the apparent activation energy of the global combustion reactions was determined. The results showed a linear drop in the apparent activation energy with the increase in the percentage of the cetane improver. Moreover, the low temperature (LT) regimes were investigated and found to be presented in base fuel, as well as cetane improver treated fuels.

Formulation of Sasol Isomerized Paraffinic Kerosene Surrogate Fuel for Diesel Engine Application Using an Ignition Quality Tester

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Ziliang Zheng ◽  
Tamer Badawy ◽  
Naeim Henein ◽  
Peter Schihl ◽  
Eric Sattler
Keyword(s):  
Diesel Engine ◽  
Ignition Delay ◽  
Alternative Fuels ◽  
Internal Combustion Engines ◽  
Cetane Number ◽  
Surrogate Fuels ◽  
Cycle Simulation ◽  
Ignition Quality ◽  
Surrogate Fuel ◽  
Ignition Quality Tester

Sasol isomerized paraffinic kerosene (IPK) is a coal-derived synthetic fuel under consideration as a blending stock with jet propellant 8 (JP-8) for use in military equipment. However, Sasol IPK is a low ignition quality fuel with derived cetane number (DCN) of 31. The proper use of such alternative fuels in internal combustion engines (ICEs) requires the modification in control strategies to operate engines efficiently. With computational cycle simulation coupled with surrogate fuel mechanism, the engine development process is proved to be very effective. Therefore, a methodology to formulate Sasol IPK surrogate fuels for diesel engine application using ignition quality tester (IQT) is developed. An in-house developed matlab code is used to formulate the appropriate mixture blends, also known as surrogate fuel. And aspen hysys is used to emulate the distillation curve of the surrogate fuels. The properties of the surrogate fuels are compared to those of the target Sasol IPK fuel. The DCNs of surrogate fuels are measured in the IQT and compared with the target Sasol IPK fuel at the standard condition. Furthermore, the ignition delay, combustion gas pressure, and rate of heat release (RHR) of Sasol IPK and its formulated surrogate fuels are analyzed and compared at five different charge temperatures. In addition, the apparent activation energies derived from chemical ignition delay of the surrogate fuel and Sasol IPK are determined and compared.

Effect of Inlet Air Temperature on Auto-Ignition of Fuels With Different Cetane Number and Volatility

2011 ◽  
Author(s):  
Chandrasekharan Jayakumar ◽  
Ziliang Zheng ◽  
Umashankar M. Joshi ◽  
Walter Bryzik ◽  
Naeim A. Henein ◽  
...  
Keyword(s):  
Air Temperature ◽  
Ignition Delay ◽  
Fuel Injection ◽  
Cetane Number ◽  
Delay Period ◽  
Inlet Temperature ◽  
Ignition Process ◽  
Ultra Low Sulfur Diesel ◽  
Auto Ignition ◽  
Ignition Delay Period

This paper investigates the effect of air inlet temperature on the auto-ignition of fuels that have different CN and volatility in a single cylinder diesel engine. The inlet air temperature is varied over a range of 30°C to 110°C. The fuels used are ultra-low-sulfur-diesel (ULSD), JP-8 (two blends with CN 44.1 & 31) and F-T SPK. Detailed analysis is made of the rate of heat release during the ignition delay period, to determine the effect of fuel volatility and CN on the auto-ignition process. A STAR-CD CFD model is applied to simulate the spray behavior and gain more insight into the processes that immediately follow the fuel injection including evaporation, start of exothermic reactions and the early stages of combustion. The mole fractions of different species are determined during the ignition delay period and their contribution in the auto-ignition process is examined. Arrhenius plots are developed to calculate the global activation energy for the auto-ignition reactions of these fuels. Correlations are developed for the ID and the mean air temperature and pressure.

Experimental Validation of a Three-Component Surrogate for Sasol-Isoparaffinic Kerosene in Single Cylinder Diesel Engine and Ignition Quality Tester

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Samy Alkhayat ◽  
Manan Trivedi ◽  
Naeim Henein ◽  
Sampad Mukhopadhyay ◽  
Peter Schihl
Keyword(s):  
Diesel Engine ◽  
Experimental Validation ◽  
Cetane Number ◽  
Negative Temperature ◽  
Single Cylinder ◽  
Combustion Behavior ◽  
Auto Ignition ◽  
Temperature Combustion ◽  
Ignition Quality ◽  
Ignition Quality Tester

Surrogates development is important to extensively investigate the combustion behavior of fuels. Development of comprehensive surrogates has been focusing on matching chemical and physical properties of their target fuel to mimic its atomization, evaporation, mixing, and auto-ignition behavior. More focus has been given to matching the derived cetane number (DCN) as a measure of the auto-ignition quality. In this investigation, we carried out experimental validation of a three-component surrogate for Sasol-Isoparaffinic Kerosene (IPK) in ignition quality tester (IQT) and in an actual diesel engine. The surrogate fuel is composed of three components (46% iso-cetane, 44% decalin, and 10% n-nonane on a volume basis). The IQT experiments were conducted as per ASTM D6890-10a. The engine experiments were conducted at 1500 rpm, two engine loads, and two injection timings. Analysis of ignition delay (ID), peak pressure, peak rate of heat release (RHR), and other combustion phasing parameters showed a closer match in the IQT than in the diesel engine. Comparison between the surrogate combustion behavior in the diesel engine and IQT revealed that matching the DCN of the surrogate to its respective target fuel did not result in the same negative temperature coefficient (NTC) profile—which led to unmatched combustion characteristics in the high temperature combustion (HTC) regimes, despite the same auto-ignition and low temperature combustion (LTC) profiles. Moreover, a comparison between the combustion behaviors of the two fuels in the IQT is not consistent with the comparison in the diesel engine, which suggests that the surrogate validation in a single-cylinder diesel engine should be part of the surrogate development methodology, particularly for low ignition quality fuels.

Formulation of Sasol IPK Surrogate Fuel for Diesel Engine Application Using an Ignition Quality Tester (IQT)

2016 ◽  
Author(s):  
Ziliang Zheng ◽  
Tamer Badawy ◽  
Naeim Henein ◽  
Peter Schihl ◽  
Eric Sattler
Keyword(s):  
Diesel Engine ◽  
Ignition Delay ◽  
Cetane Number ◽  
Combustion Gas ◽  
Surrogate Fuels ◽  
Aspen Hysys ◽  
Ignition Quality ◽  
Apparent Activation Energies ◽  
Surrogate Fuel ◽  
Ignition Quality Tester

This paper presents an approach to develop Sasol IPK (Iso-Paraffinic Kerosene) surrogate fuels for diesel engine application using Ignition Quality Tester (IQT). The methodology includes: 1) in-house developed MATLAB code to formulate the appropriate mixture blends, 2) Aspen HYSYS to develop the distillation curve and compares it to the target Sasol IPK fuel, 3) IQT to measure the derived cetane number (DCN) of surrogate fuels and compare it with the target Sasol IPK fuel, 4) analysis of autoignition and combustion characteristics for Sasol IPK surrogate fuels. The ignition delay, combustion gas pressure, and rate of heat release of Sasol IPK and its formulated surrogate fuel are analyzed and compared at five different charge temperatures. Furthermore, the apparent activation energies derived from chemical ignition delay of the surrogate fuel and Sasol IPK are determined and compared.

scholarly journals Auto-Ignition and Spray Characteristics of n-Heptane and iso-Octane Fuels in Ignition Quality Tester

2018 ◽  
Author(s):  
Mohammed Jaasim Mubarak Ali ◽  
Ayman Elhagrasy ◽  
Mani Sarathy ◽  
Sukho Chung ◽  
Hong G. Im
Keyword(s):  
Spray Characteristics ◽  
Auto Ignition ◽  
Ignition Quality ◽  
Ignition Quality Tester

scholarly journals Rational Design and Testing of Anti-Knock Additives

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4923
Author(s):  
Andrew D. Ure ◽  
Manik K. Ghosh ◽  
Maria Rappo ◽  
Roland Dauphin ◽  
Stephen Dooley
Keyword(s):  
Rational Design ◽  
Reaction Pathway ◽  
Cetane Number ◽  
Research Octane Number ◽  
Ignition Quality ◽  
Ignition Quality Tester ◽  
Generic Design ◽  
The Relationship ◽  
Design And Testing

An innovative and informed methodology for the rational design and testing of anti-knock additives is reported. Interaction of the additives with OH● and HO2● is identified as the key reaction pathway by which non-metallic anti-knock additives are proposed to operate. Based on this mechanism, a set of generic design criteria for anti-knock additives is outlined. It is suggested that these additives should contain a weak X-H bond and form stable radical species after hydrogen atom abstraction. A set of molecular structural, thermodynamic, and kinetic quantities that pertain to the propensity of the additive to inhibit knock by this mechanism are identified and determined for a set of 12 phenolic model compounds. The series of structural analogues was carefully selected such that the physical thermodynamic and kinetic quantities could be systematically varied. The efficacy of these molecules as anti-knock additives was demonstrated through the determination of the research octane number (RON) and the derived cetane number(DCN), measured using an ignition quality tester (IQT), of a RON 95 gasoline treated with 1 mole % of the additive. The use of the IQT allows the anti-knock properties of potential additives to be studied on one tenth of the scale, compared to the analogous RON measurement. Using multiple linear regression, the relationship between DCN/RON and the theoretically determined quantities is studied. The overall methodology reported is proposed as an informed alternative to the non-directed experimental screening approach typically adopted in the development of fuel additives.

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