1,721,098 research outputs found
A Lumped Parameter Model for Diesel Soot Morphology Evaluation and Emission Control
No full textDiesel engine emission standards have become more and more severe in recent years. The use of diesel particulate filters (DPFs) is a consolidated technology to reduce the emission of particulate matter out of such engines. This work is aimed at presenting a global lumped parameter for onboard applications to estimate soot morphology and its effects on DPF performances. Starting from diesel soot production during combustion, soot morphology is evaluated in terms of fractal dimension and radii of gyration. The morphology of particulate matter influences the permeability of soot deposit inside the DPF: the growth of soot layer and the consequent pressure loss are evaluated during the loading phase in different sections of the trap. Finally, the temperature trend during regeneration is computed, as a function of the amount of soot accumulated in the different zones of the DPF. The results are compared to experimental measures from the literature and to 3D-computational fluid dynamics (3D-CFD) simulations. © 2012 IMechE
Multiscale methodology for microbial fuel cell performance analysis
No full textMicrobial Fuel Cells (MFCs) are bio-electrochemical devices that directly convert organic substrates into electrical energy, by exploiting micro-organism metabolism at the electrodes. Such a technology has been shown to be promising in dealing with the waste management issue. In fact, by means of these systems, the waste disposal issue may be turned into an economic opportunity. In this work, we develop a three-dimensional numerical model grounded on the lattice Boltzmann method (LBM) to analyze the electrochemical performance of MFCs. Despite a simplified, yet effective, modeling of the electrochemical mechanisms driving the motion of ions inside the reactor, the proposed computational approach is capable of accurately capture the main involved physical phenomena and provide a fair estimation of the ion distribution within the batch reactor. The numerical predictions are then compared with available experimental data for a similar layout of solid-waste MFCs. Despite some differences in the prediction of the concentration-loss phase, which is not clearly observable in the experiments, the results obtained by the proposed methodology show that either power and polarization curves reflect the general trends of MFCs operation. This highlights the significant potential of the present computational approach for the accurate evaluation of MFC performance
Evaluating the electrochemical and power performances of microbial fuel cells across physical scales: A novel numerical approach
No full textNumerical simulation of MFC performance: a Lattice Boltzmann study
No full textIn this work, a novel numerical approach is proposed for the simulation of electrochemical and power performance of Microbial Fuel Cells (MFC). Our model is based on the Lattice Boltzmann Method, a numerical approach based on an optimized formulation of Boltzmann's Kinetic Equation, which has been successfully applied to phenomena of technical and engineering interest in recent years. Employing a multi-component LBM solver, an accurate prediction of species transport and electrochemical reactions is achieved inside the reactor chamber. The direct conversion of organic substrate into e− and H+ as by-products of microbes metabolism has been modeled according to previous experimental activity. The physical and electrochemical characteristics of anode and cathode electrodes have been accounted for and their effects on internal species transport and charge transfer is accurately simulated. The good agreement between our results and the experiments in literature highlight the reliability and versatility of LBM to predict the performance of MFCs and to shed light on the complex phenomena occurring inside the reactors
Simulating Engineering Flows through Complex Porous Media via the Lattice Boltzmann Method
Full text linkIn this paper, recent achievements in the application of the lattice Boltzmann method (LBM) to complex fluid flows are reported. More specifically, we focus on flows through reactive porous media, such as the flow through the substrate of a selective catalytic reactor (SCR) for the reduction of gaseous pollutants in the automotive field; pulsed-flow analysis through heterogeneous catalyst architectures; and transport and electro-chemical phenomena in microbial fuel cells (MFC) for novel waste-to-energy applications. To the authors’ knowledge, this is the first known application of LBM modeling to the study of MFCs, which represents by itself a highly innovative and challenging research area. The results discussed here essentially confirm the capabilities of the LBM approach as a flexible and accurate computational tool for the simulation of complex multi-physics phenomena of scientific and technological interest, across physical scales
Dynamic symmetry-breaking in mutually annihilating fluids with selective interfaces
No full textThe selective entrapment of mutually annihilating species within a phase-changing carrier fluid is explored by both analytical and numerical means. The model takes full account of the dynamic heterogeneity which arises as a result of the coupling between hydrodynamic transport, dynamic phase-transitions and chemical reactions between the participating species, in the presence of a selective droplet interface. Special attention is paid to the dynamic symmetry breaking between the mass of the two species entrapped within the expanding droplet as a function of time. It is found that selective sources are much more effective symmetry breakers than selective diffusion. The present study may be of interest for a broad variety of advection-diffusion-reaction phenomena with selective fluid interfaces, including the problem of electroweak baryogenesis
On the effects of reactant flow rarefaction on heterogeneous catalysis: A regularized lattice Boltzmann study
No full textIn this paper, a numerical investigation on heterogeneous catalysis is performed by means of a Regularized Lattice BGK approach. The effects of different values of the reactant flow Knudsen numbers are evaluated, in terms of conversion efficiency and penetration inside the structure of a nano-porous gold ingot. The results are in line with experimental evidence in the literature and open interesting perspectives for the optimal design of future nano-catalytic devices
- …
