The Study on PCCI Mode of Diesel Engine Fueled with Methanol/Dimethyl Ether

2014 ◽  
Vol 607 ◽  
pp. 629-632
Author(s):  
Yan Yan ◽  
Yu Sheng Zhang
Keyword(s):  
Dimethyl Ether ◽  
Alternative Fuels ◽  
Volume Fraction ◽  
Good Alternative ◽  
Diffusion Combustion ◽  
Compression Ignition ◽  
Temperature Reaction ◽  
High Temperature Reaction ◽  
Three Stages ◽  
And Diffusion

Taking into account China's abundant coal resources, methanol and DME(Dimethyl Ether) obtained from coal are good alternative fuels. The research project is to utilize the fuel of DME and methanol in diesel engines for new combustion models PCCI (Premixed Charge Compression Ignition).The tests of the PCCI mode with different boundary conditions were studied on PCCI test bench. PCCI combustion is consisted of three stages: low temperature reaction of DME, high-temperature reaction of DME and diffusion combustion reaction of methanol. DME as combustion improver should be kept relatively low concentration, and with the decrease of methanol, its concentration need to be reduced. Methanol and formaldehyde are important parts of HC emission, their volume fraction was about 70%.

Study of high-pressure air jet controlled compression ignition with compound thermodynamic cycle for combustion and emission formation process

2020 ◽  
pp. 146808742096933
Author(s):  
Xiangyu Meng ◽  
Sicheng Liu ◽  
Jingchen Cui ◽  
Jiangping Tian ◽  
Wuqiang Long ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Low Temperature ◽  
Formation Process ◽  
Combustion Process ◽  
Thermodynamic Cycle ◽  
Compression Ignition ◽  
Temperature Reaction ◽  
Air Jet ◽  
High Temperature Reaction

A novel method called high-pressure air (HPA) jet controlled compression ignition (JCCI) based on the compound thermodynamic cycle was investigated in this work. The combustion process of premixed mixture can be controlled flexibly by the high-pressure air jet compression, and it characterizes the intensified low-temperature reaction and two-stage high-temperature reaction. The three-dimensional (3D) computational fluid dynamics (CFD) numerical simulation was employed to study the emission formation process and mechanism, and the effects of high-pressure air jet temperature and duration on emissions were also investigated. The simulation results showed that the NOx formation is mainly affected by the first-stage high-temperature reaction due to the higher reaction temperature. Overall, this combustion mode can obtain ultra-low NOx emission. The second-stage high-temperature reaction plays an important role in the CO and THC formation caused by the mixing effect of the high-pressure air and original in-cylinder mixture. The increasing air jet temperature leads to a larger high-temperature in-cylinder region and more fuel in the first-stage reaction, and therefore resulting in higher NOx emission. However, the increasing air jet temperature can significantly reduce the CO and THC emissions. For the air jet duration comparisons, both too short and too long air jet durations could induce higher NOx emission. A higher air jet duration would result in higher CO emission due to the more high-pressure air jet with relatively low temperature.

scholarly journals Ignition Process and Flame Lift-Off Characteristics of dimethyl ether (DME) Reacting Spray

2021 ◽  
Vol 7 ◽  
Author(s):  
Khanh Duc Cung ◽  
Ahmed Abdul Moiz ◽  
Xiucheng Zhu ◽  
Seong-Young Lee
Keyword(s):  
Dimethyl Ether ◽  
Alternative Fuels ◽  
Chemical Properties ◽  
Injection Pressure ◽  
High Reactivity ◽  
Combustion Characteristic ◽  
Spray Combustion ◽  
Ignition Process ◽  
Compression Ignition ◽  
Lift Off

Advanced combustion systems that utilize different combustion modes and alternative fuels have significantly improved combustion performance and emissions compared to conventional diesel or spark-ignited combustions. As an alternative fuel, dimethyl ether (DME) has been receiving much attention as it runs effectively under low-temperature combustion (LTC) modes such as homogeneous charge compression ignition (HCCI) and reactivity control combustion ignition (RCCI). Under compression-ignition (CI), DME can be injected as liquid fuel into a hot chamber, resulting in a diesel-like spray/combustion characteristic. With its high fuel reactivity and unique chemical formula, DME ignites easily but produces almost smokeless combustion. In the current study, DME spray combustion under several different conditions of ambient temperature (Tamb = 750–1100 K), ambient density (ρamb = 14.8–30 kg/m3), oxygen concentration (O2 = 15–21%), and injection pressure (Pinj = 75–150 MPa) were studied. The results from both experiments (constant-volume combustion vessel) and numerical simulations were used to develop empirical correlations for ignition and lift-off length. Compared to diesel, the established correlation of DME shows a similar Arrhenius-type expression. Sensitivity studies show that Tamb and Pinj have a stronger effect on DME's ignition and combustion than other parameters. Finally, this study provides a simplified conceptual mechanism of DME reacting spray under high reactivity ambient (high Tamb, high O2) and LTC conditions. Finally, this paper discusses engine operating strategies using a non-conventional fuel such as DME with different reactivity and chemical properties.

Accurate High-Temperature Reaction Networks for Alternative Fuels: Butanol Isomers

2010 ◽  
Vol 49 (21) ◽  
pp. 10399-10420 ◽  
Author(s):  
Kevin M. Van Geem ◽  
Steven P. Pyl ◽  
Guy B. Marin ◽  
Michael R. Harper ◽  
William H. Green
Keyword(s):  
High Temperature ◽  
Alternative Fuels ◽  
Reaction Networks ◽  
Temperature Reaction ◽  
High Temperature Reaction

Experimental Study on In-Cylinder Pressure Oscillations of Homogenous Charge Compression Ignition–Direct Injection Combustion Engine Fueled With Dimethyl Ether

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Junxing Hou ◽  
Jianwei Liu ◽  
Yongqiang Wei ◽  
Zhiqiang Jiang
Keyword(s):  
Dimethyl Ether ◽  
Frequency Band ◽  
Combustion Engine ◽  
Combustion Process ◽  
Pressure Oscillation ◽  
Diffusion Combustion ◽  
Discrete Wavelet ◽  
Compression Ignition ◽  
Cylinder Pressure ◽  
Pressure Oscillations

The in-cylinder pressure oscillations of a homogeneous charge compression ignition (HCCI)-DI engine fueled with dimethyl ether (DME) have been investigated using discrete wavelet transform (DWT) based on four different wavelet functions. The in-cylinder pressure is decomposed into three levels that contain three details D1, D2, and D3, and an approximation A1. In normal combustion, there are no obvious pressure impacts in three details due to smooth combustion process. The abnormal pressure oscillations occur in three details in knocking combustion, and the oscillation is most intense in D1. Its frequency band 5–10 kHz is the knock frequency band, and most high-frequency pressure oscillations and wavelet energy are in this frequency band. The pressure oscillations are located in the premixed combustion stage and diffusion combustion stage. Characteristics of in-cylinder pressure oscillations can be extracted using four wavelet functions “db4,” “db8,” “sym4,” and “sym8.” Extract abilities of four wavelet functions are different and wavelet db4 is suitable for pressure oscillation detection.

Numerical study of the combustion mechanism of a homogeneous charge compression ignition engine fuelled with dimethyl ether and methane, with a detailed kinetics model

2005 ◽  
Vol 219 (10) ◽  
pp. 1213-1223 ◽  
Author(s):  
M Yao ◽  
J Qin ◽  
Z Zheng
Keyword(s):  
Heat Release ◽  
Dimethyl Ether ◽  
Homogeneous Charge Compression Ignition ◽  
Numerical Study ◽  
Kinetics Model ◽  
Compression Ignition ◽  
Temperature Reaction ◽  
Compression Ignition Engine ◽  
Auto Ignition ◽  
Homogeneous Charge

The auto-ignition and combustion mechanisms of dimethyl ether (DME) in a fourstroke homogeneous charge compression ignition (HCCI) engine were investigated using a zero-dimensional thermodynamic model coupled with a detailed chemical kinetics model. The results indicate that DME displays two-stage auto-ignition, and heat release with a low-temperature reaction and a high-temperature reaction (HTR). Heat release with the HTR can be separated into two stages: blue flame and hot flame. HCCI ignition is controlled by hydrogen peroxide (H2O2) decomposition, and OH plays a very important role in HCCI combustion. Formaldehyde (CH2O) is the main source of H2O2. Based on the sensitivity analysis of chemical reactions, the major paths of the DME reaction occurring in the engine cylinder are clarified. The major paths of the DME reaction is H-atom abstraction from DME, followed by the first addition of O2 and second addition of O2, and then oxidation to formaldehyde (CH2O), the formyl radical (HCO), and finally carbon monoxide (CO). CO oxidation occurs at the hot flame by the elementary reaction CO + OH = CO2 + H. At leaner DME concentrations, CO cannot be completely converted to carbon dioxide (CO2), and the process will result in high CO emissions.

Engine performance and emission characteristics of a compression ignition engine fuelled with diesel/dimethoxymethane blends

2005 ◽  
Vol 219 (7) ◽  
pp. 905-914 ◽  
Author(s):  
Y Ren ◽  
Z H Huang ◽  
D M Jiang ◽  
L X Liu ◽  
K Zeng ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Mass Fraction ◽  
Volume Fraction ◽  
Engine Performance ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Performance And Emission ◽  
Fuel Blends ◽  
Performance And Emissions ◽  
Combustion Phase

The performance and emissions of a compression ignition engine fuelled with diesel/dimethoxymethane (DMM) blends were studied. The results showed that the engine's thermal efficiency increased and the diesel equivalent brake specific fuel consumption (b.s.f.c.) decreased as the oxygen mass fraction (or DMM mass fraction) of the diesel/DMM blends increased. This change in the diesel/DMM blends was caused by an increased fraction of the premixed combustion phase, an oxygen enrichment, and an improvement in the diffusive combustion phase. A remarkable reduction in the exhaust CO and smoke can be achieved when operating on the diesel/DMM blend. Flat NO x/smoke and thermal efficiency/smoke curves are presented when operating on the diesel/DMM fuel blends, and a simultaneous reduction in both NO x and smoke can be realized at large DMM addition. Thermal efficiency and NO x give the highest value at 2 per cent oxygen mass fraction (or 5 per cent DMM volume fraction) for the combustion of diesel/DMM blends.

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