Tamer Badawy

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

Abstract : 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), 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 bar, 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 autoignition 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.

Effect of design and operating parameters on the ion current in a single-cylinder diesel engine

Ion current has been the subject of extensive research in gasoline engines forin-cylinder combustion sensing and as a feedback signal for closed-loop engine control. The sources of the ion current in gasoline engines have been identified. Such identification is not the case in diesel engines. This paper presents experimental data and analysis of the ion current produced in a single-cylinder diesel engine equipped with an electronically controlled common-rail-injection system using an accessible engine control unit. The experiments cover a wide range of engine speeds, loads, injection pressures, and injection timings. The effect of each operating parameter on the shape of the ion current signal, as well as its amplitude, timing, and phase shift relative to the rate of heat release, are determined.

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

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.Copyright

Detection of Combustion Resonance Using an Ion Current Sensor in Diesel Engines

This paper discusses the use of an ion current sensor to detect combustion resonance in a heavy duty direct injection diesel engine. A modified glow plug is used to measure the ion current in addition to its main function in warming up the combustion chamber. A comparison is made between the combustion resonance determined from the signals of an ion current sensor, a cylinder pressure transducer and an engine vibration sensor. Experiments are conducted on a four cylinder, turbo-charged 4.5L diesel engine to determine the potential of using the ion current sensor to detect combustion resonance under different injection pressures and exhaust gas recirculation rates. It is concluded that the ion current signal can be used to determine the timing, amplitude, frequency and duration of the resonance. The sensor output has the potential to be used as a feedback signal to the ECU (Electronic Control Unit) to minimize engine vibration and noise.Copyright

Ion current, combustion and emission characteristics in an automotive common rail diesel engine

Advanced electronically controlled diesel engines require a feedback signal to the ECU to adjust different operating parameters and meet demands for power, better fuel economy and low emissions. Different types of in-cylinder combustion sensors are being considered to produce this signal. This paper presents results of an experimental investigation on the characteristics of the ion current in an automotive diesel engine equipped with a common rail injection system. The engine is a 1.9 L, 4-cylinder, direct injection diesel engine. Experiments covered different engine loads and injection pressures. The relationships between the ion current, combustion parameters and engine out NO emissions and opacity are presented. The analysis of the experimental data identified possible sources of the ion current produced in diesel engines.Copyright

Detection of combustion resonance using an ion current sensor in diesel engines

This paper discusses the use of an ion current sensor to detect combustion resonance in a heavy duty direct injection diesel engine. A modified glow plug is used to measure the ion current in addition to its main function in warming up the combustion chamber. A comparison is made between the combustion resonance determined from the signals of an ion current sensor, a cylinder pressure transducer and an engine vibration sensor. Experiments are conducted on a four cylinder, turbo-charged 4.5L diesel engine to determine the potential of using the ion current sensor to detect combustion resonance under different injection pressures and exhaust gas recirculation rates. It is concluded that the ion current signal can be used to determine the timing, amplitude, frequency and duration of the resonance. The sensor output has the potential to be used as a feedback signal to the ECU (Electronic Control Unit) to minimize engine vibration and noise.Copyright

Ion Current, Combustion and Emission Characteristics in an Automotive Common Rail Diesel Engine

Advanced electronically controlled diesel engines require a feedback signal to the ECU to adjust different operating parameters and meet demands for power, better fuel economy and low emissions. Different types of in-cylinder combustion sensors are being considered to produce this signal. This paper presents results of an experimental investigation on the characteristics of the ion current in an automotive diesel engine equipped with a common rail injection system. The engine is a 1.9 L, 4-cylinder, direct injection diesel engine. Experiments covered different engine loads and injection pressures. The relationships between the ion current, combustion parameters and engine out NO emissions and opacity are presented. The analysis of the experimental data identified possible sources of the ion current produced in diesel engines.Copyright

Experimental Validation and Combustion Modeling of a JP-8 Surrogate in a Single Cylinder Diesel Engine

Abstract : Experimental Validation: At the test conditions analyzed, the two-component S2 surrogate fairly reproduced the following characteristics of the target JP-8: -Ignition delays -Pressure, RHR, mass-averaged gas temperature -Engine-out emissions (CO, HC, NOX), with an exception of the absolute PM values. 3D CFD Simulation: -The simulation results were in fairly good agreement with the experimental data for the surrogate. The two-component S2 surrogate could be a reasonable choice for its use in further investigations on the target JP-8.

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

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.Copyright

Multisensing fuel injector in turbocharged gasoline direct injection engines

With the increasingly stringent emissions and fuel economy standards, there is a need to develop new advanced in-cylinder sensing techniques to optimize the operation of internal combustion engine. In addition, reducing the number of on-board sensors needed for proper engine monitoring over the life time of the vehicle would reduce the cost and complexity of the electronic system.This paper presents a new technique to enable one engine component, the fuel injector, to perform multiple sensing tasks in addition to its primary task of delivering the fuel into the cylinder. The injector is instrumented within an electric circuit to produce a signal indicative of some injection and combustion parameters in electronically controlled spark ignition direct injection (SIDI) engines. The output of the multi sensing fuel injector (MSFI) system can be used as a feedback signal to the engine control unit (ECU) for injection timing control and diagnosis of the injection and combustion processes. A comparison between sensing capabilities of the multi-sensing fuel injector and the spark plug-ion sensor under different engine operating conditions is also included in this study. In addition, the combined use of the ion current signals produced by the MSFI and the spark plug for combustion sensing and control is demonstrated.© 2013 ASME