John Batteh

Analytical Assessment of Simplified Transient Fuel Tests for Vehicle Transient Fuel Compensation

Good air/fuel ratio (A/F) control is essential to high quality combustion performance, drivability and emissions in internal combustion engine powered vehicles. Cold start and transient fuel wall wetting effects cause significant A/F control challenges in port fuel injected (PFI) engines. Transient fuel compensation (TFC) strategies are used to help control the A/F during cold starts and transient load and RPM conditions for good vehicle performance, but developing optimum TFC strategies and calibrations in a vehicle with many competing effects is very difficult. Thus, simplified transient tests such as fuel or throttle perturbation tests are often used to develop and validate new strategies or calibrations for use in vehicle. This paper will illustrate the use of a validated physical model to analytically assess the value of fuel and throttle perturbation tests for developing a TFC calibration for vehicle use.

Modeling Transient Fuel Effects with Variable Cam Timing

The physics of the mixture preparation process plays a critical role in transient engine control, a key enabler for satisfying increasingly stringent emissions requirements. This paper presents a fully transient, coupledmodel in Modelica for the liquid fuel behavior and thermodynamic engine cycle including thermal effects for a port fuel injection engine. Details of both the liquid fuel transport and cycle simulation models are provided. The integrated model is used to examine the effects of variable cam timing on the transient fuel behavior including comparisons between simulation results and experimental data under a variety of engine operating conditions.

A Transient, Multi-Cylinder Engine Model Using Modelica

This paper describes a transient, thermodynamic, crank angle-based engine model in Modelica that can be used to simulate a range of advanced engine technologies. A single cylinder model is initially presented and described, along with its validation against steady-state dynamometer test data. Issues related to this single cylinder validation are discussed, including the appropriate conservation of hot residual gases under very early intake valve opening (IVO) conditions. From there, the extension from a single cylinder to a multi-cylinder V8 engine model is explained and simulation results are presented for a transient cylinder-deactivation scenario on a V8 engine.

Update on Small Modular Reactors Dynamic System Modeling Tool: Web Application

Previous reports focused on the development of component and system models as well as end-to-end system models using Modelica and Dymola for two advanced reactor architectures: (1) Advanced Liquid Metal Reactor and (2) fluoride high-temperature reactor (FHR). The focus of this report is the release of the first beta version of the web-based application for model use and collaboration, as well as an update on the FHR model. The web-based application allows novice users to configure end-to-end system models from preconfigured choices to investigate the instrumentation and controls implications of these designs and allows for the collaborative development of individual component models that can be benchmarked against test systems for potential inclusion in the model library. A description of this application is provided along with examples of its use and a listing and discussion of all the models that currently exist in the library.

Analytic Evaluation of Engine NVH Robustness Due to Manufacturing Variations

In an effort to improve quality, shorten engine development times, and reduce costly and time-consuming experimental work, analytic modeling is being used upstream in the product development process to evaluate engine robustness to noise factors. This paper describes a model-based method for evaluating engine NVH (Noise, Vibration, and Harshness) robustness due to manufacturing variations for a statistically significant engine population. A brief discussion of the cycle simulation model and its capabilities is included. The methodology consists of Monte Carlo simulations involving several noise factors to obtain the crank-angle resolved response of the combustion process and Fourier analysis of the resulting engine torque. Further analysis of the Fourier results leads to additional insights regarding the relative importance of and sensitivity to the individual noise factors. While the cost and resources required to experimentally evaluate a large engine population can be prohibitive, the analytical modeling proved to be a cost-effective way of analyzing the engine robustness taking into account manufacturing process capability.Copyright

Update on Small Modular Reactors Dynamics System Modeling Tool -- Molten Salt Cooled Architecture

The Small Modular Reactor (SMR) Dynamic System Modeling Tool project is in the third year of development. The project is designed to support collaborative modeling and study of various advanced SMR (non-light water cooled) concepts, including the use of multiple coupled reactors at a single site. The objective of the project is to provide a common simulation environment and baseline modeling resources to facilitate rapid development of dynamic advanced reactor SMR models, ensure consistency among research products within the Instrumentation, Controls, and Human-Machine Interface (ICHMI) technical area, and leverage cross-cutting capabilities while minimizing duplication of effort. The combined simulation environment and suite of models are identified as the Modular Dynamic SIMulation (MoDSIM) tool. The critical elements of this effort include (1) defining a standardized, common simulation environment that can be applied throughout the program, (2) developing a library of baseline component modules that can be assembled into full plant models using existing geometry and thermal-hydraulic data, (3) defining modeling conventions for interconnecting component models, and (4) establishing user interfaces and support tools to facilitate simulation development (i.e., configuration and parameterization), execution, and results display and capture.

Dynamic Simulation of Small Modular Reactors Using Modelica

Small modular reactors (SMRs) offer potential for addressing the nation’s long-term energy needs. However, the project design cycle for new reactor concepts is lengthy. As part of the Department of Energy’s Advanced SMR research and development program, Oak Ridge National Laboratory (ORNL) is developing a Dynamic System Modeling Tool (MoDSIM) to facilitate rapid instrumentation and controls studies of SMR concepts.Traditional nuclear reactor design makes use of verified and validated codes to meet the strict quality assurance requirements of the licensing process for the Nuclear Regulatory Commission. However, there are significant engineering analyses and high-level decisions required prior to the rigorous design phase. These analyses typically do not require high-fidelity codes. Different organizations and researchers may examine various plant configuration options prior to formal design activities. Engineers and managers must continuously make down-selection decisions regarding potential reactor architectures and subsystems. Traditionally, the modeling of these complex systems has been based on legacy models. Considerable time and effort are necessary to understand and manipulate these legacy models. For trade-space studies, two developments in the model-based systems engineering space represent a significant advancement in the ability of engineering tools to meet these demands. The first is Modelica: a nonproprietary, equation-based, object-oriented modeling language for cyber-physical systems. The second is the Functional Mockup Interface: a standardized, open interface for model exchange, simulation, and deployment.ORNL’s MoDSIM tool makes use of these developments and is intended to provide a flexible and robust dynamic system-modeling environment for SMRs. This includes single or multiple reactors, perhaps sharing common resources, or producing both electricity and process heat for local consumption or feeding a regional grid. MoDSIM uses the open-source modeling language (Modelica) and incorporates a user interface, coupled dynamic models, and analysis capabilities that will enable non-expert modelers to perform sophisticated end-to-end system simulations of both neutronic and thermal-hydraulic models. This approach enables open-source and crowd-source-type collaborations for model development of SMRs in an approach similar to open-source and open-design techniques currently used for software production and complex system design. As part of the tool development, an example SMR was chosen (advanced liquid metal reactor [ALMR]) and the ALMR models developed and interface tools demonstrated. For initial verification purposes, the results from these Modelica simulations are compared with the results documented for the earlier ALMR power-reactor innovative small-module concept. These results, as well as initial demonstrations of the tool for different control strategies, are presented in this paper.Copyright