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Technical Paper

19-Color H2O Absorption Spectrometer Applied for Real-Time In-Cylinder Gas Thermometry in an HCCI Engine

1 An all fiber-optic sensor has been developed to measure H2O mole fraction and gas temperature in an HCCI engine. This absorption-spectroscopy-based sensor utilizes a broad wavelength (1320 to 1380 nm) source (supercontinua generated by a microchip laser) and a series of fiber Bragg gratings (19 gratings centered on unique water absorption peaks) to track the formation and temperature of combustion water vapor. The spectral coverage of the system promises improved measurement accuracy over two-line diode-laser based systems. Meanwhile, the simplicity of the fiber Bragg grating chromatic dispersion approach significantly reduces the data reduction time and cost relative to previous supercontinuum-based sensors. The data provided by the system is expected to enhance studies of the chemical kinetics which govern HCCI ignition as well as HCCI modeling efforts.
Technical Paper

1D Fluid Dynamic Modeling of Unsteady Reacting Flows in the Exhaust System with Catalytic Converter for S.I. Engines

This paper deals with some recent advances in the field of 1D fluid dynamic modeling of unsteady reacting flows in complex s.i. engine pipe-systems, involving a catalytic converter. In particular, a numerical simulation code has been developed to allow the simulation of chemical reactions occurring in the catalyst, in order to predict the chemical specie concentration in the exhaust gas from the cylinder to the tailpipe outlet, passing through the catalytic converter. The composition of the exhaust gas, discharged by the cylinder and then flowing towards the converter, is calculated by means of a thermodynamic two-zone combustion model, including emission sub-models. The catalytic converter can be simulated by means of a 1D fluid dynamic and chemical approach, considering the laminar flow in each tiny channel of the substrate.
Journal Article

1D Thermo-Fluid Dynamic Modeling of Reacting Flows inside Three-Way Catalytic Converters

In this work a detailed model to simulate the transient behavior of catalytic converters is presented. The model is able to predict the unsteady and reacting flows in the exhaust ducts, by solving the system of conservation equations of mass, momentum, energy and transport of reacting chemical species. The en-gine and the intake system have not been included in the simulation, imposing the measured values of mass flow, gas temperature and chemical composition as a boundary condition at the inlet of the exhaust system. A detailed analysis of the diffusion stage triggering is proposed along with simplifications of the physics, finalized to the reduction of the calculation time. Submodels for water condensation and its following evaporation on the monolith surface have been taken into account as well as oxygen storage promoted by ceria oxides.
Technical Paper

1D Thermo-Fluid Dynamic Modelling of a S.I. Engine Exhaust System for the Prediction of Warm-Up and Emission Conversion during a NEDC Cycle

This work describes an experimental and numerical investigation of the thermal transient of i.c. engine exhaust systems. A prototype of exhaust system has been investigated during a NEDC cycle in two different configurations. Firstly an uncoated catalyst has been adopted to consider only the effect of the gas-wall heat transfer. The measurements have been repeated on the same exhaust system equipped with a coated catalyst to point out the contribution of the chemical reactions to the thermal transient of the system. The measured values have been compared to the predicted results carried out with a 1D thermo fluid dynamic code, developed in-house to account for the thermal transient of the system and the chemical reactions occurring in the catalyst.
Technical Paper

1D Unsteady Flows with Chemical Reactions in the Exhaust Duct-System of S.I. Engines: Predictions and Experiments

This paper describes some recent advances of the research work concerning the 1D fluid dynamic modeling of unsteady reacting flows in s.i. engine pipe-systems, including pre-catalysts and main catalysts. The numerical model GASDYN developed in previous work has been further enhanced to enable the simulation of the catalyst. The main chemical reactions occurring in the wash-coat have been accounted in the model, considering the mass transfer between gas and solid phase. The oxidation of CO, C3H6, C3H8, H2 and reduction of NO, the steam-reforming reactions of C3H6, C3H8, the water-gas shift reaction of CO have been considered. Moreover, an oxygen-storage sub-model has been introduced, to account for the behavior of Cerium oxides. A detailed thermal model of the converter takes into account the heat released by the exothermic reactions as a source term in the heat transfer equations. The influence of the insulating mat is accounted.
Technical Paper

2D-Simulation of Ignition Induced by Electrical Discharges

Growing interest in pollutant emission reduction has increased the importance of numerical simulations of spark ignition as a first step in IC engine combustion. In this work, we present simulations involving the coupling of flow, chemical reactions and molecular transport with the discharge processes. The main focus hereby is to investigate the early stages of the formation of a flame kernel in a two-dimensional, cylindrical geometry with electrodes. The computational results shown here include the initial shock-determined phase after the breakdown of the channel, but also the transition to flame propagation for a methane-air mixture.
Technical Paper

3D-CFD Simulation of DI-Diesel Combustion Applying a Progress Variable Approach Accounting for Detailed Chemistry

A chemical sub-model for realistic CFD simulations of Diesel engines is developed and demonstrated by application to some test cases. The model uses a newly developed progress variable approach to incorporate a realistic treatment of chemical reactions into the description of the reactive flow. The progress variable model is based on defining variables that represent the onset and temporal development of chemical reactions before and during self ignition, as well as the stage of the actual combustion. Fundamental aspects of the model, especially its physical motivation and finding a proper progress variable, are discussed, as well as issues of practical implementation. Sample calculations of Diesel-typical combustion scenarios are presented which are based on the progress-variable model, showing the capability of the model to realistically describe the ignition-and combustion phase.
Technical Paper

3M Approach to Implementing Life Cycle Management

3M is committed to continuously improving products and their manufacture toward the goal of sustainability. The 3M Life Cycle Management (LCM) program has been established to implement this goal. It utilizes a matrix tool to facilitate the review. The matrix consists of LCM Stage (Material Acquisition, R&D Operations, Manufacturing Operations, and Customer Use/Disposal) and Impact (Environment, Health, Safety, and Energy/Resources). The program is coordinated at the staff level by the Corporate Product Responsibility group. The corporate goal is to apply LCM to all new and existing products. The LCM program started with evaluations of new products within business units. Since 3M produces more than 60,000 products manufactured from more than 10,000 different raw materials, the routine evaluation of individual products challenges available staff and business unit resources. A technology-based approach for doing LCMs has been implemented to meet the challenge.
Technical Paper

A 1D Model for Diesel Sprays under Reacting Conditions

In this paper, a new 1D combustion model is presented. It is expected to combine good predictive capacities with a contained CPU time, and could be used for engine design. It relies on a eulerian approach, based on Musculus 1D transient spray model. The latter has been extended to model vaporizing, reacting sprays. The general features of the model are first presented. Then various sub models (spray angle and dilatation, vaporization, thermodynamic properties) are detailed. Chemical kinetics are described with a global scheme to keep computational time low. The spray discretization (mesh) and angle model are first discussed through a sensitivity analysis. The model results are then compared to experiments from ECN data base (SANDIA) realized in constant volume bombs, for both inert and reacting cases. Some detailed analysis of model results are performed, including comparisons of vaporizing and non-vaporizing cases, as well as inert and reacting cases.
Technical Paper

A 5-Zone Model to Improve the Diagnosis Capabilities of a Rapid Compression-Expansion Machine (RCEM) in Autoignition Studies

In this work, a 5-zone model has been applied to replicate the in-cylinder conditions evolution of a Rapid Compression-Expansion Machine (RCEM) in order to improve the chemical kinetic analyses by obtaining more accurate simulation results. To do so, CFD simulations under motoring conditions have been performed in order to identify the proper number of zones and their relative volume, walls surface and temperature. Furthermore, experiments have been carried out in an RCEM with different Primary Reference Fuels (PRF) blends under homogeneous conditions to obtain a database of ignition delays and in-cylinder pressure and temperature evolution profiles. Such experiments have been replicated in CHEMKIN by imposing the heat losses and volume profiles of the experimental facility using a 0-D 1-zone model. Then, the 5-zone model has been analogously solved and both results have been compared to the experimental ones.
Technical Paper

A Basic Overview on Brake Disc Wear

Wear of brake disc is normally faced with sophisticated experimental methods, a basic overview on the phenomena related to disc wear is presented in this paper. DTV consists in a heterogeneous wear of the disc surface and it is caused by two factors: run-out and the mechanism of disc wear. The importance of DTV is due to the vehicle vibrations that high DTV values can cause during braking. A model, that considers iron oxide layer evolution on disc surface, can evidence some of the principal characteristics of disc wear. In this model the wear rates of disc gray cast iron and iron oxide layer are considered as some of the principal factors in DTV evolution, as well as the kinetics of the chemical reactions involved.
Technical Paper

A CAD Interface for a Chemical Process Design Package

FLOWTRAN and PROCESS are engineering design packages which simulate the steady state operation of units commonly used in the chemical and petroleum industries. Given a rigorously structured data input file, these packages calculate stream properties (flow rate, composition, etc.) and unit design variables (distillation column size, pump rpm, etc.). FLOW.CPL has been developed to provide a graphical interface that will generate a FLOWTRAN compatible input file using the MEDUSA CAD system. The CAD model is built by interactively abstracting elements (representing unit operations) from a symbol library and placing them on a MEDUSA drawing sheet. The connectivity between the unit operations is provided by the user simply by connecting inputs to outputs. Additional stream information (temperature, pressure, composition, etc.) is provided by using associative blocks called clumps.
Technical Paper

A Canopy Model for Plant Growth Within a Growth Chamber: Mass and Radiation Balance for the Above Ground Portion

As humans move into outer space, need for air, clean water and food require that green plants be grown within all planetary colonies. The complexities of ecosystems require a sophisticated understanding of the interactions between the atmosphere, all nutrients, and life forms. While many experiments must be done to find the relationships between mass flows and chemical/energy transformations, it seems necessary to develop generalized models to understand the limitations of plant growth. Therefore, it is critical to have a robust modelling capability to provide insight into potential problems as well as to direct efficient experimentation. Last year we reported on a simple leaf model which focused upon the mass transfer of gases, radiation/heat balances, and the production of photosynthetically produced carbohydrate. That model indicated some of the plant processes which had to be understood in order to obtain parameters specific for each species.
Technical Paper

A Chemical Containment Model for the General Purpose Work Station

Contamination control is a critical safety requirement imposed on experiments flying on board the Spacelab. The General Purpose Work Station, a Spacelab support facility used for life sciences space flight experiments, is designed to remove volatile compounds from its internal airpath and thereby minimize contamination of the Spacelab. This is accomplished through the use of a large, multi-stage filter known as the Trace Contaminant Control System. Many experiments planned for the Spacelab require the use of toxic, volatile fixatives in order to preserve specimens prior to post-flight analysis. The NASA-Ames Research Center SLS-2 payload, in particular, necessitated the use of several toxic, volatile compounds in order to accomplish the many inflight experiment objectives of this mission. A model was developed based on earlier theories and calculations which provides conservative predictions of the resultant concentrations of these compounds given various spill scenarios.
Technical Paper

A Chemical Industry's View of Application Needs

Current trends in application technology indicate an increasing realization on the part of manufacturers and users of agricultural chemicals of the important role that application techniques and/or equipment play in the overall success of pesticide application. The trends that are most significantly influencing the way chemicals are currently applied include: increased emphasis on improving the accuracy of application increased use of low volume application (3-8 GPA) renewed interest in use of granular application increased use of conservation tillage increased emphasis on reduction in environmental contamination, both within and outside the target area increased use of highly active cam-pounds
Technical Paper

A Chemical Method for the Visualisation of Flow Maldistribution in a Catalytic Converter

Exhaust gas flow maldistribution can strongly affect the performance of catalytic converters. As part of an on-going programme concerned with optimising converter designs, flow maldistribution within catalyst monoliths resulting from the use of different shaped inlet cones was investigated. Computational fluid dynamics (CFD) techniques were used to predict gas velocities within the catalyst, and reaction of low levels of hydrogen sulfide in the gas was used to visualise the velocity profile on monoliths coated with a lead acetate indicator. This was done both in laboratory-scale experiments at room temperature with low flow-rates, and in a vehicle exhaust system under reduced temperature conditions. Flow patterns were produced for an underfloor catalyst system under real driving conditions with this unobtrusive chemical technique.
Technical Paper

A Combustion Model for Multi-Component Fuels Based on Reactivity Concept and Single-Surrogate Chemistry Representation

High fidelity engine simulation requires realistic fuel models. Although typical automotive fuels consist of more than few hundreds of hydrocarbon species, researches show that the physical and chemical properties of the real fuels could be represented by appropriate surrogate fuel models. It is desirable to represent the fuel using the same set of physical and chemical surrogate components. However, when the reaction mechanisms for a certain physical surrogate component is not available, the chemistry of the unmatched physical component is described using that of a similar chemical surrogate component at the expense of accuracy. In order to reduce the prediction error while maintaining the computational efficiency, a method of on-the-fly reactivity adjustment (ReAd) of chemical reaction mechanism along with fuel re-distribution based on reactivity is presented and tested in this study.
Technical Paper

A Combustion Products Analyzer for Contingency Use During Thermodegradation Events on Spacecraft

As mission length and the number and complexity of payload experiments increase, so does the probability of thermodegradation contingencies (e.g. fire, chemical release and/or smoke from overheated components or burning materials), which could affect mission success. When a thermodegradation event occurs on board a spacecraft, potentially hazardous levels of toxic gases could be released into the internal atmosphere. Experiences on board the Space Shuttle have clearly demonstrated the possibility of small thermodegradation events occurring during even relatively short missions. This paper will describe the Combustion Products Analyzer (CPA), which is being developed under the direction of the Toxicology Laboratory at Johnson Space Center to provide necessary data on air quality in the Shuttle following a thermodegradation incident.
Technical Paper

A Comparison of Boundary Layer Treatments for Heat Transfer in IC Engines

Three different models, the law-of-the-wall, a modified law-of-the-wall, and an approximate one-dimensional solution to the energy equation are compared for the spatially-resolved prediction of engine heat tranfer. The multidimensional hydrodynamic code KIVA is used for the fluid mechanic simulation. Two different engine geometries are studied; one being a pancake-shaped chamber, and the other a bowl-in-piston geometry. The comparisons are done for a range of initial conditions of gas flow. Rates-of-pressure-rise were also varied to represent rates typical of those encountered in motored engines, and those found in fired engines. Comparisons with experimental results show that the heat transfer predictions using the law-of-the-wall may be in error when source terms such as the transient, work and chemical energy terms have a significant effect in determining the temperature profile in the boundary layer.
Technical Paper

A Comparison of Engine Oil Viscosity, Emulsion Formation, and Chemical Changes for M85 and Gasoline-Fueled Vehicles in Short-Trip Service

Accumulation of fuel, water, acids, insolubles, and metals in engine oil is documented and compared for variable-fueled (fuel containing up to 85 percent methanol) and gasoline-fueled vehicles in short-trip service. The oil temperature at which various contaminants are removed is noted. As a consequence of emulsion formation, the viscosity of the oil in the M85-fueled vehicles increased. Due to the presence of gasoline, the viscosity of the oil in the gasoline-fueled vehicles decreased. Equations were developed to explain both the viscosity reduction due to gasoline and the viscosity increase due to emulsion-forming contaminants (water and methanol).