Enabling robust simulation of polyoxymethylene dimethyl ether 3 (PODE3) combustion in engines

2021 ◽  
pp. 146808742110183
Author(s):  
Qinjie Lin ◽  
Kun Lin Tay ◽  
Feiyang Zhao ◽  
Wenming Yang
Keyword(s):  
Reaction Mechanism ◽  
Laminar Flame ◽  
Direct Injection ◽  
Concentration Profiles ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Species Concentration ◽  
Ignition Delay Times ◽  
Engine Combustion ◽  
Constant Volume Combustion Chamber

PODE3 reaction mechanism developments are still in the early stages with very limited research. In particular, reaction mechanisms to characterize PODE3 combustion are neither sufficiently compact nor robust for 3D numerical simulations. Hence, the current work seeks to develop a compact yet reliable PODE3 reaction mechanism, embedded with appropriate chemistry to describe polycyclic aromatic hydrocarbon reactions. A decoupling methodology has been employed to achieve the desired outcome. The final mechanism comprises only 120 species and 560 reactions even after including components of diesel and gasoline surrogates. It has been validated with ignition delay times, laminar flame speeds, jet-stirred reactor species concentration profiles, flame species concentration profiles, extinction strain rates, heat release rates in constant volume combustion chamber, homogeneous charge compression ignition engine combustion, and direct injection compression ignition engine combustion. In a numerical investigation conducted using gasoline/diesel/PODE3 blends, soot emissions are observed to decrease with PODE3 increment, which establishes PODE3 as a promising additive. Intriguingly, the current study has also discovered that with 15% PODE3 addition, soot and its precursors will increase in concentration during combustion, though this effect will be outweighed by oxidative effects towards the end. Overall, the new mechanism has been proven suitable and feasible for engine simulations.

Mapping the combustion modes of a dual-fuel compression ignition engine

2021 ◽  
pp. 146808742110183
Author(s):  
Jonathan Martin ◽  
André Boehman
Keyword(s):  
Direct Injection ◽  
Fuel Combustion ◽  
Dual Fuel ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Combustion Modes ◽  
Si Engines ◽  
Dual Fuel Combustion ◽  
Soot Emissions ◽  
Ci Engines

Compression-ignition (CI) engines can produce higher thermal efficiency (TE) and thus lower carbon dioxide (CO2) emissions than spark-ignition (SI) engines. Unfortunately, the overall fuel economy of CI engine vehicles is limited by their emissions of nitrogen oxides (NOx) and soot, which must be mitigated with costly, resource- and energy-intensive aftertreatment. NOx and soot could also be mitigated by adding premixed gasoline to complement the conventional, non-premixed direct injection (DI) of diesel fuel in CI engines. Several such “dual-fuel” combustion modes have been introduced in recent years, but these modes are usually studied individually at discrete conditions. This paper introduces a mapping system for dual-fuel CI modes that links together several previously studied modes across a continuous two-dimensional diagram. This system includes the conventional diesel combustion (CDC) and conventional dual-fuel (CDF) modes; the well-explored advanced combustion modes of HCCI, RCCI, PCCI, and PPCI; and a previously discovered but relatively unexplored combustion mode that is herein titled “Piston-split Dual-Fuel Combustion” or PDFC. Tests show that dual-fuel CI engines can simultaneously increase TE and lower NOx and/or soot emissions at high loads through the use of Partial HCCI (PHCCI). At low loads, PHCCI is not possible, but either PDFC or RCCI can be used to further improve NOx and/or soot emissions, albeit at slightly lower TE. These results lead to a “partial dual-fuel” multi-mode strategy of PHCCI at high loads and CDC at low loads, linked together by PDFC. Drive cycle simulations show that this strategy, when tuned to balance NOx and soot reductions, can reduce engine-out CO2 emissions by about 1% while reducing NOx and soot by about 20% each with respect to CDC. This increases emissions of unburnt hydrocarbons (UHC), still in a treatable range (2.0 g/kWh) but five times as high as CDC, requiring changes in aftertreatment strategy.

Performance of multi-dimensional models for simulating diesel premixed charge compression ignition engine combustion using low- and high-pressure injectors

2005 ◽  
Vol 6 (5) ◽  
pp. 475-486 ◽  
Author(s):  
S-C Kong ◽  
Y Ra ◽  
R D Reitz
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Spray Angle ◽  
Low Temperature Combustion ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Detailed Chemistry ◽  
Engine Combustion ◽  
Temperature Combustion ◽  
Hsdi Diesel Engine

An engine CFD model has been developed to simulate premixed charge compression ignition (PCCI) combustion using detailed chemistry. The numerical model is based on the KIVA code that is modified to use CHEMKIN as the chemistry solver. The model was applied to simulate ignition, combustion, and emissions processes in diesel engines operated to achieve PCCI conditions. Diesel PCCI experiments using both low- and high-pressure injectors were simulated. For the low-pressure injector with early injection (close to intake valve closure), the model shows that wall wetting can be minimized by using a pressure-swirl atomizer with a variable spray angle. In the case of using a high-pressure injector, it is found that late injection (SOI = 5 ° ATDC) benefits soot emissions as a result of low-temperature combustion at highly premixed conditions. The model was also used to validate the emission reduction potential of an HSDI diesel engine using a double injection strategy that favours PCCI conditions. It is concluded that the present model is useful to assess future engine combustion concepts, such as PCCI and low-temperature combustion (LTC).

Ozone-Assisted Combustion—Part I: Literature Review and Kinetic Study Using Detailed n-Heptane Kinetic Mechanism

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Christopher Depcik ◽  
Michael Mangus ◽  
Colter Ragone
Keyword(s):  
Ignition Delay ◽  
Equivalence Ratio ◽  
Atomic Oxygen ◽  
Direct Injection ◽  
Kinetic Mechanism ◽  
Combustion Model ◽  
Ozone Decomposition ◽  
Compression Ignition ◽  
Review Of The Literature ◽  
Compression Ignition Engine

In this first paper, the authors undertake a review of the literature in the field of ozone-assisted combustion in order to summarize literature findings. The use of a detailed n-heptane combustion model including ozone kinetics helps analyze these earlier results and leads into experimentation within the authors' laboratory using a single-cylinder, direct-injection compression ignition engine, briefly discussed here and in more depth in a following paper. The literature and kinetic modeling outcomes indicate that the addition of ozone leads to a decrease in ignition delay, both in comparison to no added ozone and with a decreasing equivalence ratio. This ignition delay decrease as the mixture leans is counter to the traditional increase in ignition delay with decreasing equivalence ratio. Moreover, the inclusion of ozone results in slightly higher temperatures in the cylinder due to ozone decomposition, augmented production of nitrogen oxides, and reduction in particulate matter through radial atomic oxygen chemistry. Of additional importance, acetylene levels decrease but carbon monoxide emissions are found to both increase and decrease as a function of equivalence ratio. This work illustrates that, beyond a certain level of assistance (approximately 20 ppm for the compression ratio of the authors' engine), adding more ozone has a negligible influence on combustion and emissions. This occurs because the introduction of O3 into the intake causes a temperature-limited equilibrium set of reactions via the atomic oxygen radical produced.

Combustion and vibration study of a direct injection compression ignition engine fuelled with Moringa oleifera biodiesel-diesel blends

2021 ◽  
pp. 1-24
Author(s):  
Jaikumar Sagari ◽  
Srinivas Vdapalli ◽  
Rajasekhar Medidi ◽  
Ravi Sankar Hota ◽  
Sankara Narayana Kota ◽  
...  
Keyword(s):  
Moringa Oleifera ◽  
Direct Injection ◽  
Compression Ignition ◽  
Compression Ignition Engine

Operating Characteristics of Natural Gas Fueled Homogeneous Charge Compression Ignition Engine

1999 ◽  
Author(s):  
Y. Kawabata ◽  
K. Nakagawa ◽  
F. Shoji
Keyword(s):  
Natural Gas ◽  
Homogeneous Charge Compression Ignition ◽  
Nox Emission ◽  
Compression Ignition ◽  
Operating Characteristics ◽  
Compression Ignition Engine ◽  
Gas Engine ◽  
Engine Combustion ◽  
Gas Fueled ◽  
Homogeneous Charge

Abstract Recently, a new design of engine combustion that achieves higher efficiency and less NOx emission has been proposed. Some researchers have started studying the concept, which is called Homogeneous Charge Compression Ignition (HCCI), but there have been few reports on investigations using a future prospective alternative fuel, natural gas. In this study, natural gas fueled operation of HCCI using a single cylinder gas engine was conducted. Operating and exhaust characteristics were obtained. Experimental data confirmed the potential of higher efficiency and less NOx emission, though THC and CO were higher. Based on these data, the feasibility of this concept for gas engines is also examined.

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