Primary & Secondary Reference Fuel Effects as a Function of Compression Ratio in a CFR Diesel Engine

2021 ◽  
Author(s):  
Kevin Burnett ◽  
Ashwani Gupta ◽  
Dianne Luning Prak ◽  
Jim Cowart
Keyword(s):  
Compression Ratio ◽  
Fuel Injection ◽  
Cetane Number ◽  
Operating Conditions ◽  
Combustion Analysis ◽  
Fast Kinetics ◽  
Engine Torque ◽  
Start Of Injection ◽  
Primary Reference ◽  
Primary Reference Fuels

Abstract Primary Reference Fuels (PRFs) and Secondary Reference Fuels (SRFs) in the range of cetane from 30 to 60 were operated in a Waukesha Diesel Cooperative Fuels Research (CFR) engine under operating conditions that emulate the cetane rating test. Due to the large number of test points in this study, the exact ASTM cetane rating protocol was not followed precisely, however these results are representative of cetane characterization testing with very similar equivalence ratio and combustion phasing across a broad range of Ignition Delays (IGDs) that varied as a result of Compression Ratio (CR) changes in the eleven to twenty-two range. Intake air temperature was operated both heated, as in the cetane rating test, as well as at ambient laboratory conditions. Additional research instrumentation was added beyond the standard CFR equipment for advanced combustion analysis. Combustion analysis shows that engine torque and efficiency increase significantly with increases in CR. At longer IGDs representative of the cetane rating test (13 deg IGD), the increase in IGD with reduced cetane number is relatively linear. For all of the fuels tested, IGD steadily monotonically decreases with increased CR significantly by more than a factor of two. Shorter IGDs lead to longer burn durations; fuel effect differences become less important at very high CRs. Associated companion analysis shows that at the time of fuel injection (Start Of Injection – SOI), cylinder pressure roughly doubles over the CRs studied, however, cylinder charge temperature only moderately increases. This effect leads to a doubling in cylinder air charge concentration at the highest CRs showing an important effect on the fast kinetics at high CRs. A common IGD correlation was evaluated showing good agreement except for the high CN fuel. New IGD correlations are also presented.

Proportional–Integral Controller Design for Combustion-Timing Feedback, From n-Heptane to Iso-Octane in Compression–Ignition Engines

2017 ◽  
Vol 140 (5) ◽  
Author(s):  
Gabriel Ingesson ◽  
Lianhao Yin ◽  
Rolf Johansson ◽  
Per Tunestål
Keyword(s):  
Ignition Delay ◽  
Controller Design ◽  
Negative Temperature ◽  
Operating Conditions ◽  
Measurement Noise ◽  
Noise Sensitivity ◽  
Proportional Integral ◽  
Primary Reference ◽  
The Difference ◽  
Primary Reference Fuels

The problem of designing robust and noise-insensitive proportional–integral (PI) controllers for pressure-sensor-based combustion-timing control was studied through simulation. Different primary reference fuels (PRF) and operating conditions were studied. The simulations were done using a physics-based, control-oriented model with an empirical ignition-delay correlation. It was found that the controllable region in between the zero-gain region for early injection timings and the misfire region for late injection timings is strongly PRF dependent. As a result, it was necessary to adjust intake temperature to compensate for the difference in fuel reactivity prior to the controller design. With adjusted intake temperature, PRF-dependent negative-temperature coefficient (NTC) behavior gave different system characteristics for the different fuels. The PI controller design was accomplished by solving the optimization problem of maximizing disturbance rejection and tracking performance subject to constraints on robustness and measurement-noise sensitivity. Optimal controller gains were found to be limited by the high system gain at late combustion timings and high-load conditions; furthermore, the measurement-noise sensitivity was found to be higher at the low-load operating points where the ignition delay is more sensitive to variations in load and intake conditions. The controller-gain restrictions were found to vary for the different PRFs; the optimal gains for higher PRFs were lower due to a higher system gain, whereas the measurement-noise sensitivity was found to be higher for lower PRFs.

scholarly journals Study of the engine configuration effect on the maximum achievable load in CAI using water injection

2020 ◽  
pp. 146808742096085
Author(s):  
J Valero-Marco ◽  
B Lehrheuer ◽  
JJ López ◽  
S Pischinger
Keyword(s):  
Compression Ratio ◽  
Engine Speed ◽  
Gasoline Engine ◽  
Fuel Injection ◽  
Water Injection ◽  
Maximum Load ◽  
Operating Conditions ◽  
Work Related ◽  
Operating Strategies ◽  
Injection Strategies

The approach of this research is to enlarge the knowledge about the methodologies to increase the maximum achievable load degree in the context of gasoline CAI engines. This work is the continuation of a previous work related to the study of the water injection effect on combustion, where this strategy was approached. The operating strategies to introduce the water and the interconnected settings were deeply analyzed in order to optimize combustion and to evaluate its potential to increase the maximum load degree when operating in CAI. During these initial tests, the engine was configured to enhance the mixture autoignition. The compression ratio was high compared to a standard gasoline engine, and suitable fuel injection strategies were selected based on previous studies from the authors to maximize the reactivity of the mixture, and get a stable CAI operation. Once water injection proved to provide encouraging results, the next step dealt in this work, was to go deeper and explore its effects when the engine configuration is more similar to a conventional gasoline engine, trying to get CAI combustion closer to production engines. This means, mainly, lower compression ratios and different fuel injection strategies, which hinders CAI operation. Finally, since all the previous works were performed at constant engine speed, the engine speed was also modified in order to see the applicability of the defined strategies to operate under CAI conditions at other operating conditions. The results obtained show that all these modifications are compatible with CAI operation: the required compression ratio can be reduced, in some cases the injection strategies can be simplified, and the increase of the engine speed leads to better conditions for CAI combustion. Thanks to the analysis of all this data, the different key parameters to manage this combustion mode are identified and shown in the paper.

Startup and Steady-State Performance of a New Renewable Hydroprocessed Depolymerized Cellulosic Diesel Fuel in Multiple Diesel Engines

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Eric Bermudez ◽  
Andrew McDaniel ◽  
Terrence Dickerson ◽  
Dianne Luning Prak ◽  
Len Hamilton ◽  
...  
Keyword(s):  
Steady State ◽  
Diesel Engine ◽  
Cetane Number ◽  
Operating Conditions ◽  
Engine Operation ◽  
Start Of Injection ◽  
Ignition Quality ◽  
Engine Testing ◽  
Engine Start ◽  
Distillate Fuel

A new hydroprocessed depolymerized cellulosic diesel (HDCD) fuel has been developed using a process which takes biomass feedstock (principally cellulosic wood) to produce a synthetic fuel that has nominally ½ cycloparaffins and ½ aromatic hydrocarbons in content. This HDCD fuel with a low cetane value (derived cetane number from the ignition quality tester, DCN = 27) was blended with naval distillate fuel (NATO symbol F-76) in various quantities and tested in order to determine how much HDCD could be blended before diesel engine operation becomes problematic. Blends of 20% HDCD (DCN = 45), 30%, 40% (DCN = 41), and 60% HDCD (DCN = 37) by volume were tested with conventional naval distillate fuel (DCN = 49). Engine start performance was evaluated with a conventional mechanically direct injected (DI) Yanmar engine and a Waukesha mechanical indirect injected (IDI) Cooperative Fuels Research (CFR) diesel engine and showed that engine start times increased steadily with increasing HDCD content. Longer start times with increasing HDCD content were the result of some engine cycles with poor combustion leading to a slower rate of engine acceleration toward rated speed. A repeating sequence of alternating cycles which combust followed by a noncombustion cycle was common during engine run-up. Additionally, steady-state engine testing was also performed using both engines. HDCD has a significantly higher bulk modulus than F76 due to its very high aromatic content, and the engines showed earlier start of injection (SOI) timing with increasing HDCD content for equivalent operating conditions. Additionally, due to the lower DCN, the higher HDCD blends showed moderately longer ignition delay (IGD) with moderately shorter overall burn durations. Thus, the midcombustion metric (CA50: 50% burn duration crank angle position) was only modestly affected with increasing HDCD content. Increasing HDCD content beyond 40% leads to significantly longer start times.

scholarly journals Effects of CNG Injection Pressure on Performance, Emission and Combustion Characteristics of Multi-cylinder SI Engine

2019 ◽  
Vol 8 (3) ◽  
pp. 2383-2387
Keyword(s):  
Compression Ratio ◽  
Fuel Injection ◽  
Injection Pressure ◽  
Injection System ◽  
Combustion Analysis ◽  
Si Engine ◽  
Performance And Emission ◽  
Port Fuel Injection ◽  
Spark Timing ◽  
Fuel Injection Pressure

This Paper shows the effect of port fuel injection pressure of CNG in 3-cylinder SI Engine at Wide Open Throttle position using sequential port fuel injection system. All trials are performed on 4-stroke, 796 cc MPFI S.I engine at injection pressure of 2.0, 2.2, 2.4, 2.6, 2.8 bar for constant speed of 2500, 3000, 3500, 4000 & 4500 rpm. During the trial compression ratio is kept constant at 9.2 with Maximum Brake Torque (MBT) spark timing of 15oBTDC. Optimum torque is obtained for CNG at injection pressure of 2.6 bar and 3000 rpm. Gasoline trials are performed at same compression ratio for comparison with CNG at same injection pressure. Performance and emission characteristics with combustion analysis are performed at optimum injection pressure of 2.6 bar.

scholarly journals An Extensive Analysis of Biodiesel Blend Combustion Characteristics under a Wide-Range of Thermal Conditions of a Cooperative Fuel Research Engine

2020 ◽  
Vol 12 (18) ◽  
pp. 7666
Author(s):  
Vu H. Nguyen ◽  
Minh Q. Duong ◽  
Kien T. Nguyen ◽  
Thin V. Pham ◽  
Phuong X. Pham
Keyword(s):  
Alternative Fuels ◽  
Fossil Fuels ◽  
Fuel Injection ◽  
Cetane Number ◽  
Thermal Conditions ◽  
Combustion Characteristics ◽  
Mixing Rate ◽  
Start Of Injection ◽  
Wide Range ◽  
Physical And Chemical

Examining the influence of thermal conditions in the engine cylinder at the start of fuel injection on engine combustion characteristics is critically important. This may help to understand physical and chemical processes occurring in engine cycles and this is relevant to both fossil fuels and alternative fuels like biodiesels. In this study, six different biodiesel–diesel blends (B0, B10, B20, B40, B60 and B100 representing 0, 10, 20, 40, 60 and 100% by volume of biodiesel in the diesel–biodiesel mixtures, respectively) have been successfully tested in a cooperative fuel research (CFR) engine operating under a wide range of thermal conditions at the start of fuel injection. This is a standard cetane testing CFR-F5 engine, a special tool for fuel research. In this study, it was further retrofitted to investigate combustion characteristics along with standard cetane measurements for those biodiesel blends. The novel biodiesel has been produced from residues taken from a palm cooking oil manufacturing process. It is found that the cetane number of B100 is almost 30% higher than that of B0 and this could be attributed to the oxygen content in the biofuel. Under similar thermal conditions at the start of injection, it is observed that the influence of engine load on premixed combustion is minimal. This could be attributable to the well-controlled intake air temperature in this special engine and therefore the evaporation and mixing rate prior to the start of combustion is similar under different loading conditions. Owing to higher cetane number (CN), B100 is more reactive and auto-ignites up to 3 degrees of crank angle (DCA) earlier compared to B0. It is generally observed in this study that B10 shows a higher maximum value of in-cylinder pressure compared to that of B0 and B20. This could be evidence for lubricant enhancement when operating the engine with low-blending ratio mixtures like B10 in this case.

Pressure Sensitivity of HCCI Auto-Ignition Temperature for Oxygenated Reference Fuels

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
Ida Truedsson ◽  
Martin Tuner ◽  
Bengt Johansson ◽  
William Cannella
Keyword(s):  
Compression Ratio ◽  
Ignition Temperature ◽  
Engine Speed ◽  
Hcci Combustion ◽  
Air Temperatures ◽  
Auto Ignition ◽  
Temperature Heat ◽  
Pressure Trace ◽  
Primary Reference ◽  
Primary Reference Fuels

The current research focuses on creating a homogeneous charge compression ignition (HCCI) fuel index suitable for comparing different fuels for HCCI operation. One way to characterize a fuel is to use the auto-ignition temperature (AIT). The AIT can be extracted from the pressure trace. Another potentially interesting parameter is the amount of low temperature heat release (LTHR) that is closely connected to the ignition properties of the fuel. The purpose of this study was to map the AIT and the amount of LTHR of different oxygenated reference fuels in HCCI combustion at different cylinder pressures. Blends of n-heptane, iso-octane, and ethanol were tested in a cooperative fuels research (CFR) engine with a variable compression ratio. Five different inlet air temperatures ranging from 50 °C to 150 °C were used to achieve different cylinder pressures and the compression ratio was changed accordingly to keep a constant combustion phasing, CA50, of 3 ± 1 deg after top dead center (TDC). The experiments were carried out in lean operation with a constant equivalence ratio of 0.33 and with a constant engine speed of 600 rpm. The amount of ethanol needed to suppress the LTHR from different primary reference fuels (PRFs) was evaluated. The AIT and the amount of LTHR for different combinations of n-heptane, iso-octane, and ethanol were charted.

Coordination of fuel reactivity and injection timing to achieve highly efficient and stable gasoline compression ignition combustion in a wide load range

2020 ◽  
Vol 234 (7) ◽  
pp. 1840-1853
Author(s):  
Chenxu Jiang ◽  
Zilong Li ◽  
Guibin Liu ◽  
Yong Qian ◽  
Xingcai Lu
Keyword(s):  
High Efficiency ◽  
Pressure Rise ◽  
Injection Timing ◽  
Compression Ignition ◽  
Load Range ◽  
Start Of Injection ◽  
Rise Rate ◽  
Primary Reference ◽  
Primary Reference Fuels ◽  
Compression Ignition Combustion

Gasoline compression ignition combustion is a new combustion mode with great development potential and is highly influenced by fuel reactivity and injection strategy. This paper coordinates the fuel octane number and single-injection timing to operate gasoline compression ignition combustion with high efficiency in a wide load range, with the speed fixed at 1500 r/min. The primary reference fuels with octane numbers 60, 70, 80, and 90 were used, labeled as PRF60, PRF70, PRF80, and PRF90, respectively. The results proved that under steady-state conditions where the speed and load changed slightly, taking the fuel economy and combustion and emission performance into account, PRF60 and PRF70 should be applied at a load lower than 2 bar and 2–8 bar, respectively, and the start of injection timing should be set at 13 °CA before top dead center. When the load is higher than 8 bar, PRF90 should be applied at the start of injection timing of 11 °CA before top dead center. It is noteworthy that PRF70 under medium-load conditions could achieve the indicated thermal efficiency of up to 47%. The injection timing of PRF90 was limited to 9–1711 °CA before top dead center due to the limit of the peak value of pressure rise rate, whereas PRF60 had a wider injection timing boundary than PRF90.

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.

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