Experimental Study of Coal Liquefaction Diesel Combustion and Emissions

2013 ◽  
Vol 291-294 ◽  
pp. 1914-1919
Author(s):  
Yu Li Dai ◽  
Yi Qiang Pei ◽  
Jing Qin ◽  
Jian Ye Zhang ◽  
Yun Long Li
Keyword(s):  
Experimental Study ◽  
Heat Release ◽  
Ignition Delay ◽  
Cetane Number ◽  
Combustion Process ◽  
Load Condition ◽  
Coal Liquefaction ◽  
Soot Emissions ◽  
Co Emission ◽  
Load Conditions

An experimental study was conducted on the combustion processes and emissions of direct coal liquefaction (DDCL) and Fischer-Tropsch (FT) fuels in a single-cylinder research diesel engine. Under low load conditions (5 bar IMEP), the results show that the ignition delay is shorter for the FT fuel compared with the reference fuel (Euro IV diesel), while it is longer for the DDCL fuel compared with the reference fuel. However, under high load conditions (10-15 bar IMEP), the Cetane number (CN) shows insignificant effects on the combustion process. The premixed heat release peaks of the fuels are correlated with the ignition delays, i.e. shorter ignition delay led to lower premixed heat release peak. For the emissions, both the FT fuel and the DDCL fuel show similar NOx level to the reference fuel under the conditions tested. The two liquefaction fuels show significantly lower soot emissions than the reference fuel, specifically for the higher load conditions (>=10bar IMEP), and the FT fuel produced the lowest level of soot emissions among the three fuels. For the FT and DDCL fuels, the HC emissions are generally lower than those of the reference fuel, except for the lowest load condition, which DDCL produces slightly higher HC emission. However, the CO emission of FT is lower than the reference fuel while the CO emission of DDCL is higher. In terms of unregulated emissions, the two liquefaction fuels show insignificant difference compared with the reference fuel at very low levels.

Investigation on the spray development, the combustion characteristics and the emissions of Fischer–Tropsch fuel and diesel fuel from direct coal liquefaction

2017 ◽  
Vol 231 (13) ◽  
pp. 1829-1837 ◽  
Author(s):  
Yiqiang Pei ◽  
Jing Qin ◽  
Yuli Dai ◽  
Kun Wang
Keyword(s):  
Diesel Fuel ◽  
Ignition Delay ◽  
Cetane Number ◽  
Combustion Process ◽  
Physicochemical Characteristics ◽  
Combustion Characteristics ◽  
Coal Liquefaction ◽  
Fischer Tropsch ◽  
Planar Laser ◽  
Direct Coal Liquefaction

Diesel fuel is largely consumed by transportation services, and diesel fuel from direct coal liquefaction and Fischer–Tropsch fuel have been produced as alternatives in coal-rich areas. However, the physicochemical characteristics of the two fuels are not quite the same as those of diesel fuel derived from crude oil. Therefore, the spray development, the combustion characteristics and the emissions of diesel fuel from direct coal liquefaction, Fischer–Tropsch fuel and commercial diesel fuel were studied in this paper. The spray development was investigated by using planar laser-induced fluorescence, and the results showed that the spray characteristics of coal-liquefied fuel were similar to those of commercial diesel fuel. Diesel fuel from direct coal liquefaction has a longer ignition delay and a higher heat release rate from premixed combustion than commercial diesel fuel does because of its lower cetane number at low loads. However, the same combustion characteristics with commercial diesel fuel can be achieved by mixing diesel fuel from direct coal liquefaction and Fischer–Tropsch fuel in a ratio of 3 to 1. With increasing engine load, the in-cylinder temperature and the pressure increased which reduced the effect of the cetane number on the ignition delay and the combustion process. The regulated emissions from Fischer–Tropsch fuel were the lowest of these fuels; the unregulated emissions measured by Fourier transform infrared spectroscopy, however, were slightly higher than those of the other two fuels.

The Role of the Recirculating Gases at the Mild Combustion Regime Formation

2007 ◽  
Author(s):  
Y. Levy ◽  
V. Sherbaum ◽  
V. Erenburg
Keyword(s):  
Gas Turbine ◽  
Ignition Delay ◽  
Ignition Delay Time ◽  
Combustion Process ◽  
Combustion Regime ◽  
Reaction Products ◽  
Gas Turbine Combustor ◽  
Mild Combustion ◽  
Recirculation Rate ◽  
Co Emission

The present work is concerned with the thermodynamic and chemical kinetics of gas turbine combustor operating in the Moderate or Intense Low-oxygen Dilution (MILD) combustion regime. The objective of the present study is to evaluate analytically the effect of the recirculation rate of combustion products within the FLOXCOM gas turbine combustor on a number of combustion parameters, mainly on the ignition delay time, NOx and CO emission, minimum ignition temperature, rate of pollutant formation and the dilution rate. The study also refers to the mechanism of influence of the recirculation rate on these values. Combustion pressure and inlet air temperature are used as parameters. The gas turbine is fueled with methane. The analysis is mainly based on CHEMKIN simulations where the calculation scheme of the combustion process in the combustor is modeled by a combination of plug reactors and mixers. Due to the unique characteristics of gas turbines, inlet air temperature is directly linked to combustion pressure while assuming conventional adiabatic compression efficiencies. It is shown that free radicals, which are part of the reaction products and exists for only a short period of time within the recirculated gases, decrease ignition delay time. The importance of shortening the ignition delay is further highlighted because of the adverse effect oxygen dilution has on this parameter (dilution of the reactants by the reaction products). It was found that there is an optimal recirculation rate, which corresponds to maximum heat density. In addition, results indicate that CO emission values rise with the recirculation rate, however the NOX values are more complicated. NOX depends on recirculation rate when flame temperatures are kept held constant. The NOX emission increases and the CO emission decreases with compressor pressure ratio. The CO concentration that is evaluated in the combustion process is further reduced during last dilution stage. Finally, basic rules for design optimization of the combustor are drafted. These are based on conventional one-dimensional fluid and thermodynamic relations and on the CHEMKIN simulations.

Effects of Pre-Injection on Combustion Characteristics of a Single-Cylinder Diesel Engine

2009 ◽  
Author(s):  
M. Mittal ◽  
G. Zhu ◽  
T. Stuecken ◽  
H. J. Schock
Keyword(s):  
Diesel Engine ◽  
Combustion Process ◽  
Load Condition ◽  
Combustion Characteristics ◽  
Combustion Noise ◽  
Injection Timing ◽  
Single Cylinder ◽  
Multiple Injections ◽  
Main Injection ◽  
Load Conditions

Multiple injections used for diesel engines, especially pre- and post-injections, have the potential to reduce combustion noise and emissions with improved engine performance. This paper outlines the combustion characteristics of a single-cylinder diesel engine with multiple injections. The effects of pre-injection (multi-injection) on combustion characteristics are presented in a single-cylinder diesel engine at different engine speeds and load conditions. A common rail fuel system with a solenoid injector, driven by a peak and hold circuit, is used in this work. This enables us to control the number of injections, fuel injection timing and duration, and the fuel rail pressure that can be used to optimize the engine combustion process (e.g., eliminate engine knock). Mass fraction burned and burn durations are determined by analyzing the measured in-cylinder pressure data. Results are compared with the cases when no pre-injection was used, i.e. only main injection, at the same engine speeds and load conditions. In each study, different cases are considered with the variation in main injection timing. It is found that at full-load condition and lower engine speeds pre-injection is an effective method to alter the engine burn rate and hence to eliminate knock.

Low NOx and Low Smoke Operation of a Diesel Engine Using Gasolinelike Fuels

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Gautam Kalghatgi ◽  
Leif Hildingsson ◽  
Bengt Johansson
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Compression Ratio ◽  
Diesel Fuel ◽  
Ignition Delay ◽  
Cetane Number ◽  
Pressure Rise ◽  
Maximum Pressure ◽  
Single Cylinder ◽  
Intake Pressure

Much of the technology in advanced diesel engines, such as high injection pressures, is aimed at overcoming the short ignition delay of conventional diesel fuels to promote premixed combustion in order to reduce NOx and smoke. Previous work in a 2 l single-cylinder diesel engine with a compression ratio of 14 has demonstrated that gasoline fuel, because of its high ignition delay, is very beneficial for premixed compression-ignition compared with a conventional diesel fuel. We have now done similar studies in a smaller—0.537 l—single-cylinder diesel engine with a compression ratio of 15.8. The engine was run on three fuels of very different auto-ignition quality—a typical European diesel fuel with a cetane number (CN) of 56, a typical European gasoline of 95 RON and 85 MON with an estimated CN of 16 and another gasoline of 84 RON and 78 MON (estimated CN of 21). The previous results with gasoline were obtained only at 1200 rpm—here we compare the fuels also at 2000 rpm and 3000 rpm. At 1200 rpm, at low loads (∼4 bars indicated mean effective pressure (IMEP)) when smoke is negligible, NOx levels below 0.4 g/kWh can be easily attained with gasoline without using exhaust gas recirculation (EGR), while this is not possible with the 56 CN European diesel. At these loads, the maximum pressure-rise rate is also significantly lower for gasoline. At 2000 rpm, with 2 bars absolute intake pressure, NOx can be reduced below 0.4 g/kW h with negligible smoke (FSN<0.1) with gasoline between 10 bars and 12 bars IMEP using sufficient EGR, while this is not possible with the diesel fuel. At 3000 rpm, with the intake pressure at 2.4 bars absolute, NOx of 0.4 g/kW h with negligible smoke was attainable with gasoline at 13 bars IMEP. Hydrocarbon and CO emissions are higher for gasoline and will require after-treatment. High peak heat release rates can be alleviated using multiple injections. Large amounts of gasoline, unlike diesel, can be injected very early in the cycle without causing heat release during the compression stroke and this enables the heat release profile to be shaped.

scholarly journals Spray, Combustion, and Air Pollutant Characteristics of JP-5 for Naval Aircraft from Experimental Single-Cylinder CRDI Diesel Engine

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2362
Author(s):  
Hyungmin Lee
Keyword(s):  
Diesel Engine ◽  
Ignition Delay ◽  
Fuel Injection ◽  
Cetane Number ◽  
Combustion Process ◽  
Air Pollutant ◽  
Spray Combustion ◽  
Injection Timing ◽  
Visualization System ◽  
Single Cylinder

This study was performed to analyze the spray, combustion, and air pollutant characteristic of JP-5 fuel for naval aircraft in a spray visualization system and a single-cylinder CRDI diesel engine that can be visualized. The analysis results of JP-5 fuel were compared with DF. The spray tip penetration of JP-5 showed diminished results as the spray developed. JP-5 had the highest ROHR and ROPR regardless of the fuel injection timings. The physicochemical characteristics of JP-5, such as its excellent vaporization and low cetane number, were analyzed to prolong the ignition delay. Overall, the longer combustion period and the lower heat loss of the DF raised the engine torque and the IMEP. JP-5 showed higher O2 and lower CO2 levels than the DF fuel. The CO emission level increased as the injection timing was advanced in two test fuels, and the CO emitted from the DF fuel, which has a longer combustion period than JP-5, turned out to be lower. NOx also reduced as the fuel injection timing was retarded, but it was discharged at a higher level in JP-5 due to the large heat release. The images from the combustion process visualization showed that the flame luminosity of DF is stronger, its ignition delay is shorter, and its combustion period is longer than that of JP-5.

scholarly journals Investigating Combustion Process of N-Butanol-Diesel Blends in a Diesel Engine with Variable Compression Ratio

2021 ◽  
Vol 3 (3) ◽  
pp. 618-628
Author(s):  
György Szabados ◽  
Kristóf Lukács ◽  
Ákos Bereczky
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Compression Ratio ◽  
Release Rate ◽  
Ignition Delay ◽  
Alternative Fuels ◽  
Internal Combustion Engines ◽  
Combustion Process ◽  
Injection Angle ◽  
Combustion Properties

The search for alternative fuels for internal combustion engines is ongoing. Among the alternatives, plant-based fuels can also be mentioned. Alcohol is not a common fuel for diesel engines because the physical and chemical properties of the alcohols are closer to those of gasoline. In our research, the combustion properties of diesel-n-butanol mixtures have been investigated to obtain results on the effect of butanol blending on combustion. Among the combustion properties, ignition delay, in-cylinder pressure, and heat release rate can be mentioned. They have been observed under different compression conditions on an engine on which the compression ratio can be adjusted. The method used was a quite simple one, so the speed of the engine was set to a constant 900 rpm without load, while three compression ratios (19.92, 15.27, and 12.53) were adjusted with a fuel flow rate of 13 mL/min and the pre-injection angle of 18° BTDC. Blending butanol into the investigated fuel does not significantly affect maximal values of indicated pressure, while much more effect on the pressure rising rate can be detected. Furthermore, heat release rate and ignition delay increased at every compression ratio investigated. Despite the low blending rates of butanol in the mixtures, butanol significantly affects the combustion parameters, especially at high compression ratios.

Diethyl Ether as an Ignition Enhancer for Naphtha Creating a Drop in Fuel for Diesel

2016 ◽  
Author(s):  
R. Vallinayagam ◽  
S. Vedharaj ◽  
S. Mani Sarathy ◽  
Robert W. Dibble
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Ignition Delay ◽  
Cetane Number ◽  
Cylinder Pressure ◽  
Auto Ignition ◽  
Peak Heat Release Rate ◽  
Ignition Characteristics ◽  
Ci Engines

Direct use of naphtha in compression ignition (CI) engines is not advisable because its lower cetane number negatively impacts the auto ignition process. However, engine or fuel modifications can be made to operate naphtha in CI engines. Enhancing a fuel’s auto ignition characteristics presents an opportunity to use low cetane fuel, naphtha, in CI engines. In this research, Di-ethyl ether (DEE) derived from ethanol is used as an ignition enhancer for light naphtha. With this fuel modification, a “drop-in” fuel that is interchangeable with existing diesel fuel has been created. The ignition characteristics of DEE blended naphtha were studied in an ignition quality tester (IQT); the measured ignition delay time (IDT) for pure naphtha was 6.9 ms. When DEE was added to naphtha, IDT decreased and D30 (30% DEE + 70% naphtha) showed comparable IDT with US NO.2 diesel. The derived cetane number (DCN) of naphtha, D10 (10% DEE + 90% naphtha), D20% DEE + 80% naphtha) and D30 were measured to be 31, 37, 40 and 49, respectively. The addition of 30% DEE in naphtha achieved a DCN equivalent to US NO.2 diesel. Subsequent experiments in a CI engine exhibited longer ignition delay for naphtha compared to diesel. The peak in-cylinder pressure is higher for naphtha than diesel and other tested fuels. When DEE was added to naphtha, the ignition delay shortened and peak in-cylinder pressure is reduced. A 3.7% increase in peak in-cylinder pressure was observed for naphtha compared to US NO.2 diesel, while D30 showed comparable results with diesel. The pressure rise rate dropped with the addition of DEE to naphtha, thereby reducing the ringing intensity. Naphtha exhibited a peak heat release rate of 280 kJ/m3deg, while D30 showed a comparable peak heat release rate to US NO.2 diesel. The amount of energy released during the premixed combustion phase decreased with the increase of DEE in naphtha. Thus, this study demonstrates the suitability of DEE blended naphtha mixtures as a “drop-in” replacement fuel for diesel.

scholarly journals Effects of Injection Rate Profile on Combustion Process and Emissions in a Diesel Engine

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Fuqiang Bai ◽  
Zuowei Zhang ◽  
Yongchen Du ◽  
Fan Zhang ◽  
Zhijun Peng
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Combustion Process ◽  
Injection Rate ◽  
Injection System ◽  
Nox Emissions ◽  
Release Process ◽  
Common Rail Injection System ◽  
Soot Emissions ◽  
Rate Profile

When multi-injection is implemented in diesel engine via high pressure common rail injection system, changed interval between injection pulses can induce variation of injection rate profile for sequential injection pulse, though other control parameters are the same. Variations of injection rate shape which influence the air-fuel mixing and combustion process will be important for designing injection strategy. In this research, CFD numerical simulations using KIVA-3V were conducted for examining the effects of injection rate shape on diesel combustion and emissions. After the model was validated by experimental results, five different shapes (including rectangle, slope, triangle, trapezoid, and wedge) of injection rate profiles were investigated. Modeling results demonstrate that injection rate shape can have obvious influence on heat release process and heat release traces which cause different combustion process and emissions. It is observed that the baseline, rectangle (flat), shape of injection rate can have better balance between NOx and soot emissions than the other investigated shapes. As wedge shape brings about the lowest NOx emissions due to retarded heat release, it produces the highest soot emissions among the five shapes. Trapezoid shape has the lowest soot emissions, while its NOx is not the highest one. The highest NOx emissions were produced by triangle shape due to higher peak injection rate.

scholarly journals Experimental Study of the Effect of Intake Oxygen Concentration on Engine Combustion Process and Hydrocarbon Emissions with N-Butanol-Diesel Blended Fuel

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1310 ◽  
Author(s):  
Wei Tian ◽  
Yunlu Chu ◽  
Zhiqiang Han ◽  
Xiang Wang ◽  
Wenbin Yu ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Ignition Delay ◽  
Cetane Number ◽  
Combustion Process ◽  
Delay Period ◽  
Blended Fuel ◽  
The Difference ◽  
Hc Emissions ◽  
Oxygen Medium ◽  
Ignition Delay Period

This paper summarizes a study based on a modified, light, single-cylinder diesel engine and the effects of the physicochemical properties for n-butanol-diesel blended fuel on the combustion process and hydrocarbon (HC) emissions in the intake at a medium speed and moderate load in, an oxygen-rich environment (Coxy = 20.9–16%), an oxygen-medium environment (Coxy = 16–12%), and an oxygen-poor environment (Coxy = 12–9%). The results show that the ignition delay period is the main factor affecting the combustion process and it has a decisive influence on HC emissions. In an oxygen-medium environment, combustion duration affected by the cetane number is the main reason for the difference in HC emissions between neat diesel fuel (B00) and diesel/n-butanol blended fuel (B20), and its influence increases as the intake oxygen concentration decreases. In an oxygen-poor environment, in-cylinder combustion temperature affected by the latent heat of vaporization is the main reason for the difference in HC emissions between B00 and B20 fuels, and its influence increases as the intake oxygen concentration decreases. By comparing B20 fuel with diesel/n-butanol/2-ethylhexyl nitrate blended fuel (B20 + EHN), the difference in the ignition delay period caused by the difference in the cetane number is the main reason for the difference in HC emissions between B20 and B20 + EHN fuels in oxygen-poor environment, and the effect of this influencing factor gradually increases as the intake oxygen concentration decreases.

Low NOx and Low Smoke Operation of a Diesel Engine Using Gasoline-Like Fuels

2009 ◽  
Author(s):  
Gautam Kalghatgi ◽  
Leif Hildingsson ◽  
Bengt Johansson
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Compression Ratio ◽  
Diesel Fuel ◽  
Ignition Delay ◽  
Cetane Number ◽  
Pressure Rise ◽  
Maximum Pressure ◽  
Single Cylinder ◽  
Intake Pressure

Much of the technology in advanced diesel engines, such as high injection pressures, is aimed at overcoming the short ignition delay of conventional diesel fuels to promote premixed combustion in order to reduce NOx and smoke. Previous work in a 2 litre single cylinder diesel engine with a compression ratio of 14 has demonstrated that gasoline fuel, because of its high ignition delay, is very beneficial for premixed compression ignition compared to a conventional diesel fuel. We have now done similar studies in a smaller — 0.537 litre — single cylinder diesel engine with a compression ratio of 15.8. The engine was run on three fuels of very different auto-ignition quality — a typical European diesel fuel with a cetane number (CN) of 56, a typical European gasoline of 95 RON and 85 MON with an estimated CN of 16 and another gasoline of 84 RON and 78 MON (estimated CN of 21). The previous results with gasoline were obtained only at 1200 rpm — here we compare the fuels also at 2000 rpm and 3000 rpm. At 1200 rpm, at low loads (∼4 bar IMEP) when smoke is negligible, NOx levels below 0.4 g/kWh can be easily attained with gasoline without using EGR while this is not possible with the 56 CN European diesel. At these loads, the maximum pressure rise rate is also significantly lower for gasoline. At 2000 rpm, with 2 bar absolute intake pressure, NOx can be reduced below 0.4 g/kWh with negligible smoke (FSN <0.1) with gasoline between 10 and 12 bar IMEP using sufficient EGR while this is not possible with the diesel fuel. At 3000 rpm, with the intake pressure at 2.4 bar absolute, NOx of 0.4 g/KWh with negligible smoke was attainable with gasoline at 13 bar IMEP. Hydrocarbon and CO emissions are higher for gasoline and will require after-treatment. High peak heat release rates can be alleviated using multiple injections. Large amounts of gasoline, unlike diesel, can be injected very early in the cycle without causing heat release during the compression stroke and this enables the heat release profile to be shaped.

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