Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 15
Book Description
Microkinetic Modeling of Lean NOx Trap Storage and Regeneration
Author: Microkinetic Modeling of Lean NOx Trap Sulfation and Desulfation
Author: Simulation of Lean NOx Trap Performance with Microkinetic Chemistry and Without Mass Transfer
Author: Kinetic and Performance Studies of the Regeneration Phase of Model Pt
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
In this project a combined experimental and theoretical approach was taken to advance our understanding of lean NOx trap (LNT) technology. Fundamental kinetics studies were carried out of model LNT catalysts containing variable loadings of precious metals (Pt, Rh), and storage components (BaO, CeO2). The Temporal Analysis of Products (TAP) reactor provided transient data under well-characterized conditions for both powder and monolith catalysts, enabling the identification of key reaction pathways and estimation of the corresponding kinetic parameters. The performance of model NOx storage and reduction (NSR) monolith catalysts were evaluated in a bench scale NOx trap using synthetic exhaust, with attention placed on the effect of the pulse timing and composition on the instantaneous and cycle-averaged product distributions. From these experiments we formulated a global model that predicts the main spatio-temporal features of the LNT and a mechanistic-based microkinetic models that incorporates a detailed understanding of the chemistry and predicts more detailed selectivity features of the LNT. The NOx trap models were used to determine its ability to simulate bench-scale data and ultimately to evaluate alternative LNT designs and operating strategies. The four-year project led to the training of several doctoral students and the dissemination of the findings as 47 presentations in conferences, catalysis societies, and academic departments as well 23 manuscripts in peer-reviewed journals. A condensed review of NOx storage and reduction was published in an encyclopedia of technology.
Modeling the Regeneration Chemistry of Lean NOx Traps
Author: Byproduct Formation During Regeneration of Lean NOx Traps
Author: Josh A. PihlA Lean NOx Trap+Selective Catalytic Reduction System for Controlling the NOx Emissions from a Diesel Engine
Author: Joseph R. TheisSpatially Resolved Operando Measurements in Heterogeneous Catalytic Reactors
Author: Publisher: Academic Press
ISBN: 012812590X
Category : Technology & Engineering
Languages : en
Pages : 302
Book Description
Spatially Resolved Operando Measurements in Heterogeneous Catalytic Reactors, Volume 50, presents the latest on these essential components in the continuing search for better utilization of raw materials and energy that reduces impact on the environment. This latest release includes valuable chapters that present tactics on Understanding the performance of automotive catalysts via spatial resolution of reactions inside honeycomb monoliths, Operando spectroscopy in catalytic reactors, Spatio-temporal phenomena in monolithic reactors measured by combined spatially-resolved mass spectrometry and optical frequency domain reflectrometry, and In-situ spatially resolved techniques for the investigation of packed bed catalytic reactors: Current status and future outlook. This series presents the latest reviews of the state-of-the-art of in heterogeneous catalytic reactors and processes. Contains reviews by leading authorities in their respective areas Presents up-to-date reviews of the latest techniques in the modeling of catalytic processes Includes a broad mix of US and European authors, as well as academic, industrial and research institute perspectives Provides discussions on the connections between computation and experimental methods
Global Kinetic Modeling of Lean NOx Traps
Author: Louise OlssonPublisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages :
Book Description
Lean NOx Trap Modeling in Vehicle Systems Simulations
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 18
Book Description
A one-dimensional model for simulating lean NOx trap (LNT) performance is developed and validated using both steady state cycling data and transient data from FTP testing cycles. The model consists of the conservation equations for chemical species and energy in the bulk flow, energy of the solid walls, O2 storage and NOx storage (in the form of nitrites and nitrates). Nitrites and nitrates are formed by diffusion of NO and NO2, respectively, into sorbent particles (assumed to be hemi-spherical in shape) along with O2 and their formation rates are controlled by chemical kinetics as well as solid-phase diffusion rates of NOx species. The model also accounts for thermal aging and sulfation of LNTs. Empirical correlations are developed on the basis of published experimental data to capture these effects. These empirical correlations depend on total mileage for which the LNT has been in use, the mileage accumulated since the last desulfation event in addition to the freshly degreened catalyst characteristics. The model has been used in studies of vehicle systems (integration, performance etc.) including hybrid powertrain configurations. Since the engines in hybrid vehicles turn on and off multiple number of times during single drive cycles, the exhaust systems may encounter multiple cold start transients. Accurate modeling of catalyst warm-up and cooling is, therefore, very important to simulate LNT performance in such vehicles. For this purpose, the convective heat loss from the LNT to the ambient is modeled using a Nusselt number correlation that includes effects of both forced convection and natural convection (with later being important when vehicle is stationary). Using the model, the fuel penalty associated with operating LNTs on small diesel engine powered car during FTP drive cycles is estimated.