Abstract

Large-scale use of leaded gasoline was an important source of the neurotoxin lead in the European environment. After a sequence of regulations on the allowed gasoline lead content and, eventually, a ban on the use of lead additives in gasoline, road transport was no longer considered a source of atmospheric lead. Currently a discrepancy exists between measured atmospheric lead concentrations and model-predicted concentrations, suggesting that lead emissions to the atmosphere may be underestimated. Recently it was suggested that lead emission from unleaded gasoline combustion is still an important source and may (partly) fill the gap between modelled and observed atmospheric lead concentrations. In this paper we assess the plausibility of the latter suggestion by following various emission estimation methodologies. The uncertainty of lead emissions from road transport is further reduced by chemical analysis of fuel samples. The result of our assessment is that lead from road transport fuel combustion is not the missing lead source needed to fill the gap between modelled and observed lead concentrations. Road transport is still a source of lead through brake wear and a small contribution from exhaust emissions but this contributes no more than 5-8% of the EU25 total emission. © 2009 Elsevier B.V. All rights reserved.

Abstract

In this paper, the numerical method level set has been used to model the combustion process in an Otto two-stroke engine. The level set has been implemented in a CFD (Computational Fluid Dynamics) software based in finite volumes. The pressure and temperature fields have been obtained, such as the propagation of the flame front. In order to validate this model, the numerically obtained results have been compared with experimental data, verifying a satisfactory concordance between both of them. Besides, the level set method has been compared with other numerical procedure, showing the difference between both results.

Abstract

Mixing, ignition, and flame stabilization in a shear supersonic hydrogen-air flow is numerically studied with the RANS model of Spalart and Allmaras. A detailed chemical kinetics of hydrogen-air combustion is used in the calculations. The system of governing equations is solved with a hybrid explicit-implicit time marching scheme and the LU­SGS method. Modelling of hydrogen injection into the M = 2.44 vitiated air flow in the model Burrows-Kurkov combustor is carried out for 2D and 3D cases. The numerical results obtained are compared with available experimental data.

Abstract

Computational modeling and simulation represents a competitive and functional tool that effectively supports the study of thermochemical behavior in combustion optimization, guaranteeing reliable results through modeling, design and allowed the validation of excess thermodynamic properties applied for combustion. of the biomass of Piptocoma discolor (pigüe) from the Amazonian region of Ecuador and Latin America. The model parameters were physical, chemical and thermal through computational fluid dynamics in combustion optimization. And the mathematical model of combustion was obtained under the transport method of the species. In the simulation, the variables of primary air flow and moisture content were observed. The variable of the combustion parameters were N2, O2, CO, H, pressure, temperature, humidity, total energy and burning time of the biomass particles. The geometric configuration was developed according to the fundamental principles of CFD within Ansys Fluent to obtain the behavior of speed, turbulence, pressure, etc. of the composition of the optimal fuel 91.75% of a complete combustion and compared to other species that show 86% of the reactions of the combustion of the species.