Three-Dimensional Flamelet Simulation of Polycyclic Aromatic Hydrocarbons Formation in DI-Diesel Engines

Author(s):  
Beijing Zhong ◽  
Shuai Dang ◽  
Jun Xi

In this study, numerical simulations for an n-heptane fueled Chaochai 6102bzl direct injection diesel engine are performed in order to predict the chemical details of the combustion process and resulting polycyclic aromatic hydrocarbons (such as benzene, naphthalene, phenanthrene and pyrene) formation. The diesel geometry and reduced kinetic mechanism of n-heptane oxidation, which includes only 86 reactions and 57 species, have been developed and incorporated into the computational fluid dynamics code, FLUENT. The diesel unsteady laminar flamelet model, turbulence model and spray model have been employed in the numerical simulations. The numerical simulation results showed that the polycyclic aromatic hydrocarbons were firstly increased with the increase of diesel crank angel and then decreased, which was mostly located at the bottom of diesel combustion chamber wall.

2018 ◽  
Vol 2018 ◽  
pp. 1-5
Author(s):  
Haiying Wang ◽  
Chuantao Li

The general (α,t)-path connectivity index of a molecular graph originates from many practical problems such as three-dimensional quantitative structure-activity (3D QSAR) and molecular chirality. It is defined as Rtα(G)=∑Pt=vi1vi2⋯vit+1⊆G[d(vi1)d(vi2)⋯d(vit+1)]α, where the summation is taken over all possible paths of length t of G and we do not distinguish between the paths vi1vi2⋯vit+1 and vit+1⋯vi2vi1. In this paper, we focus on the structures of Polycyclic Aromatic Hydrocarbons (PAHn), which play a role in organic materials and medical sciences. We try to compute the exact general (α,3)-path connectivity indices of this family of hydrocarbon structures. Furthermore, we exactly derive the monotonicity and the extremal values of R3α(PAHn) for any real number α. These valuable results could produce strong guiding significance to these applied sciences.


2012 ◽  
Vol 468-471 ◽  
pp. 2993-2997
Author(s):  
Xiao Juan Liang ◽  
Xi Qin Li

Polycyclic aromatic hydrocarbons are harmful to human body and environment. In order to know the formatting rules of benzene and polycyclic aromatic hydrocarbons in gasoline combustion process, a series of tests are done in a constant volume combustion bomb. The emissions of benzene and polycyclic aromatic hydrocarbons are measured by a gas chromatography-mass spectrometry analyzer. The test results show that the benzene in combustion products comes from the incomplete combustion fuel. The free radicals out of cracking fuel may also become benzene in combustion process. Adding ethanol in fuels does not necessarily increase the emission of benzene. Formation of polycyclic aromatic hydrocarbons varies with temperature.


2011 ◽  
Vol 281 ◽  
pp. 280-285
Author(s):  
Li Song Hu ◽  
Guang Hui He ◽  
Xi Wen Liu ◽  
Yan Wang

In this paper, 34 soil samples was collected in Beihu Lake area in Wuhan, Hubei province for determination of 16 types of polycyclic aromatic hydrocarbons (PAHs), in order to study the residues of persistent organic pollutants in soil of Beihu area, GC-MS, as well as a detection method called EPA8080A, was used to detect these PAHs, including Naphthalene, Acenaphthylene, Acenaphthene, Fluorene, Phenanthrene, Anthracene, Fluoranthene, Pyrene, Benzo(a)anthracene, Chrysene, Benzo(b)fluoranthene, Benzo(k)fluoranthene, Benzo(a)pyrene, Indeno(1,2,3-cd)pyrene, Dibenzo(a,h)anthracene and Benzo(g,hi)perylene. The result showed that PAHs could be found in all the samples, and the average residue of PAHs was 4114.2 ng/g. The coefficient of variation was 0.98, which indicated a greater dispersion. The pollution was more serious in the specified district than other domestic and foreign area. The ratio of specific PAHs demonstrated that they mainly came from combustion process and then fall to the surface by means of atmospheric deposition, thus, the departments concerned should strengthen or improve the use of fuel.


2006 ◽  
Vol 310 (1-2) ◽  
pp. 159-170 ◽  
Author(s):  
Diana Matschulat ◽  
Harald Prestel ◽  
Ferdinand Haider ◽  
Reinhard Niessner ◽  
Dietmar Knopp

2020 ◽  
Vol 17 (7) ◽  
pp. 479
Author(s):  
Dongqin Tan ◽  
Jing Jin ◽  
Cuicui Guo ◽  
Dhanjai ◽  
Jiping Chen

Environmental contextRemediation of wastewater containing polycyclic aromatic hydrocarbons and metals is essential to limit adverse effects on the environment and human health. Using a simple precipitation method, we prepared porous magnetic MgO hybrids for use as a material for removing pollutants from wastewater. The material showed excellent removal performance for 12 polycyclic aromatic hydrocarbons and cadmium ions, and thus has potential applications in wastewater treatment. AbstractHierarchical porous magnetic MgO hybrids (Fe3O4/MgO) are controllably synthesised based on a facile precipitation process. The resulting material displays a three-dimensional architecture with nest-like morphology, large surface area (135.2m2 g−1) and uniform mesochannels (5–35nm). The adsorption equilibrium data of target polycyclic aromatic hydrocarbons (PAHs) on Fe3O4/MgO sorbents are described by the Langmuir isotherm model. The composites show a strong tendency for the removal of PAHs owing to their porous structure that possesses an excellent affinity for PAHs. Under the optimal conditions, a removal of more than 70% is achieved for 12 PAHs. The materials also exhibit a good removal ability of cadmium (Cd2+) from water with fast adsorption (<5min) and high removal percentage (>80%). Moreover, the composites possess sufficient magnetism for separation. To demonstrate the performance of the sorbents, Fe3O4/MgO is exposed to aqueous samples spiked with low concentrations of PAHs and Cd2+. In almost all cases, the composites are superior to the commercially available sorbents as well as un-functionalised Fe3O4 nanoparticles. Therefore, this work provides a promising approach for the simultaneous removal of PAHs and Cd2+ from water using multifunctional MgO microspheres.


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