3D CFD Modeling of a Biodiesel-Fueled Diesel Engine Based on a Detailed Chemical Mechanism

2012 ◽  
Author(s):  
Junfeng Yang ◽  
Monica Johansson ◽  
Chitralkumar Naik ◽  
Karthik Puduppakkam ◽  
Valeri Golovitchev ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Chemical Mechanism ◽  
Cfd Modeling ◽  
Detailed Chemical

scholarly journals Mechanism of Emission Reduction in HSDI Diesel Engine: Split Injection

2015 ◽  
Vol 09 (2) ◽  
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Temporal Distribution ◽  
Reaction Rates ◽  
Chemical Mechanism ◽  
Symmetric Model ◽  
Diesel Combustion ◽  
Split Injection ◽  
Engine Combustion ◽  
Experimental Values

In order to meet the stringent emission standards significant efforts have been imparted to the research and development of cleaner IC engines. Diesel combustion and the formation of pollutants are directly influenced by spatial and temporal distribution of the fuel injected. The development and validation of computational fluid dynamics (CFD) models for diesel engine combustion and emissions is described. The complexity of diesel combustion requires simulation with many complex interacting sub models in order to have a success in improving the performance and to reduce the emissions. In the present work an attempt has been made to develop a multidimensional axe-symmetric model for CI engine combustion and emissions. Later simulations have been carried out using split injection for single, double and three pulses (split injection) for which commercial validation tool FLUENT was used for simulation. The tool solves basic governing equations of fluid flow that is continuity, momentum, species transport and energy equation. Using finite volume method turbulence was modeled by using RNG K-ɛ model. Injection was modeled using La Grangian approach and reaction was modeled using non premixed combustion which considers the effects of turbulence and detailed chemical mechanism into account to model the reaction rates. The specific heats were approximated using piecewise polynomials. Subsequently the simulated results have been validated with the existing experimental values. The peak pressure obtained by simulation for single and double is 10% higher than to that of experimental value. Whereas for triple injections 5% higher than to that of experimental value. For quadruple injection the pressure has been decreased by 10% when compared to triple injection.NOX have been decreased in simulation for single, double and triple injections by 15%, 28% and 20%.For quadruple injection NOX were reduced in quadruple injection by 20% to that of triple injection. The simulated value of soot for single, double and triple injections are 12%, 22% and 12% lesser than the experimental values. For quadruple injection the soot levels were almost negligible. The simulated heat release rates for single, double and triple were reduced by 12%, 18% and 11%. For quadruple injection heat release is reduced same as to that of triple injection.

Detailed chemical mechanism of the phase transition in nano-SrTiO3 perovskite with visible luminescence

2020 ◽  
Vol 120 ◽  
pp. 108125
Author(s):  
Sonali Mehra ◽  
Swati Bishnoi ◽  
Lalit Goswami ◽  
Govind Gupta ◽  
Avanish Kumar Srivastava ◽  
...  
Keyword(s):  
Phase Transition ◽  
Chemical Mechanism ◽  
Visible Luminescence ◽  
Detailed Chemical

Simulation of n-Heptane and Surrogate Fuels for Advanced Combustion Engines (FACE) in a Single-Cylinder Compression Ignition Engine

2013 ◽  
Author(s):  
Joseph Taglialegami ◽  
Gregory Bogin ◽  
Eric Osecky ◽  
Anthony M. Dean
Keyword(s):  
Diesel Engine ◽  
Physical Properties ◽  
Heat Release ◽  
Chemical Mechanism ◽  
Computational Time ◽  
Combustion Engines ◽  
Single Cylinder ◽  
Advanced Combustion ◽  
The Face ◽  
Single Chemical

A CFD model of a HATZ diesel engine was developed for the purpose of simulating low temperature combustion (LTC) of surrogate diesel fuels for the Fuels for Advanced Combustion Engines (FACE). Initial validation of the model was performed using n-heptane data from a single cylinder HATZ diesel engine. Simulations were run with both a detailed n-heptane mechanism and several reduced mechanisms to determine the suitability of using a reduced mechanism to capture the main ignition characteristics and emissions. It was found that a 173 species n-heptane mechanism predicts start of combustion (SOC) within 0.5 crank angle degrees of the detailed 561 species mechanism. The 173 species mechanism required 27 hours of computational time to reach the end of the simulation whereas the 561 species detailed mechanism required 41 hours under the same conditions. Two additional reduced mechanisms, containing 85 and 35 species, were provided reasonable accuracy with a computational time of 8 hours and 2 hours, respectively. Due to the varying physical and chemical properties of the FACE surrogates, a sensitivity analysis of the effects of the physical properties was conducted by changing the n-heptane physical properties to those of n-hexadecane while keeping the chemistry the same. As expected, when the fuel properties of n-hexadecane (which is less volatile than n-heptane) were used with the n-heptane kinetics, SOC was delayed and the net heat release rate was reduced. The FACE fuels were developed to fulfill the need for research grade fuels that are able to represent common refinery stream fuels. Since the FACE fuels consist of hundreds of fuel components, it is not feasible to model the actual FACE fuels in a full-scale engine model. An alternative is to develop surrogates consisting of relatively few species for which detailed mechanisms are available. Even then this mechanism would need to be reduced to make the computation practical. For this work, a detailed diesel surrogate mechanism was reduced from 4016 species to 1046 species to match the characteristics for FACE fuels 1, 3, 5, 8, and 9. The surrogates only contain 4–7 species. Using the single chemical mechanism to represent five surrogate FACE fuels, it was found that ∼200°C of air preheat was required to achieve autoignition in the HATZ model compared to the 130°C of air preheat required experimentally. Initial runs have found that there were similar trends in SOC and heat release between the FACE fuel surrogate experiments and simulations for the respective fuels. Future work will require improvements on the single chemical mechanism to represent the five surrogate FACE fuels.

scholarly journals Optimization of the combustion system of a medium duty direct injection diesel engine by combining CFD modeling with experimental validation

2016 ◽  
Vol 110 ◽  
pp. 212-229 ◽  
Author(s):  
Jesus Benajes ◽  
Ricardo Novella ◽  
Jose Manuel Pastor ◽  
Alberto Hernández-López ◽  
Manabu Hasegawa ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Experimental Validation ◽  
Direct Injection ◽  
Cfd Modeling ◽  
Combustion System ◽  
Direct Injection Diesel Engine

scholarly journals CFD modeling of reactive pollutant dispersion in simplified urban configurations with different chemical mechanisms

2016 ◽  
Vol 16 (18) ◽  
pp. 12143-12157 ◽  
Author(s):  
Beatriz Sanchez ◽  
Jose-Luis Santiago ◽  
Alberto Martilli ◽  
Magdalena Palacios ◽  
Frank Kirchner
Keyword(s):  
Chemical Reactions ◽  
Chemical Mechanism ◽  
Cfd Modeling ◽  
Background Concentration ◽  
Urban Air ◽  
Large Set ◽  
Atmospheric Conditions ◽  
Traffic Emission ◽  
Wind Speeds ◽  
Cpu Time

Abstract. An accurate understanding of urban air quality requires considering a coupled behavior between the dispersion of reactive pollutants and atmospheric dynamics. Currently, urban air pollution is mostly dominated by traffic emission, where nitrogen oxides (NOx) and volatile organic compounds (VOCs) are the primary emitted pollutants. However, modeling reactive pollutants with a large set of chemical reactions, using a computational fluid dynamic (CFD) model, requires a large amount of computational (CPU) time. In this sense, the selection of the chemical reactions needed in different atmospheric conditions becomes essential in finding the best compromise between CPU time and accuracy. The purpose of this work is to assess the differences in NO and NO2 concentrations by considering three chemical approaches: (a) passive tracers (non-reactive), (b) the NOx–O3 photostationary state and (c) a reduced complex chemical mechanism based on 23 species and 25 reactions. The appraisal of the effects of chemical reactions focuses on studying the NO and NO2 dispersion in comparison with the tracer behavior within the street. In turn, the effect of including VOC reactions is also analyzed taking into account several VOC ∕ NOx ratios of traffic emission. Given that the NO and NO2 dispersion can also be affected by atmospheric conditions, such as wind flow or the background concentration from season-dependent pollutants, in this work the influence of wind speeds and background O3 concentrations are studied. The results show that the presence of ozone in the street plays an important role in NO and NO2 concentrations. Therefore, greater differences linked to the chemical approach used are found with higher O3 concentrations and faster wind speeds. This bears relation to the vertical flux as a function of ambient wind speed since it increases the pollutant exchange between the street and the overlying air. This detailed study allows one to ascertain under which atmospheric conditions the inclusion of chemical reactions are necessary for the study of NO and NO2 dispersion. The conclusions can be applied to future studies in order to establish the chemical reactions needed in terms of an accurate modeling of NO and NO2 dispersion and the CPU time required in a real urban area.

Sign in / Sign up

Export Citation Format

Share Document