1,720,973 research outputs found
Automotive Engine Modelling for Real-Time Control Using an Object-Oriented Simulation Library
No full textTheoretical simulation models are useful tools in the design of engine management systems, allowing to reduce resources invested in the product development. Their applications range from optimisation of control systems to hardware-in-the-loop testing (HIL) and to model-based control and diagnostic strategies.
Even if several control-oriented models are proposed in the open literature for spark ignited engines only in the last years a similar attention has been devoted to automotive Diesels, which on the other hand are becoming more and more widely used due to their low specific fuel consumption (and to their low CO2 specific emissions).
The paper describes a control-oriented theoretical tool developed in MatLabâ/SimuLinkâ for the simulation of a turbocharged direct injection (DI) Diesel engine, with common rail (CR) injection system and exhaust gas recirculation (EGR). Starting from a previous steady-state Mean Value Engine Model (MVEM) proposed by the author, a specific SimuLinkâ library was built up to describe components and subsystems: defined blocks can be easily assembled together in a modular structure to reproduce the whole engine layout. Quasi-steady flow and filling-and-emptying techniques are used, while combustion process is described following a single-zone approach. In the paper the library is presented, together with an application to a typical automotive CR Diesel engine
A real-time model of a small turbocharged Multijet Diesel engine: application and validation
No full textTheoretical models are useful tools in the design of engine control systems, with applications that range from the definition of optimised management systems, to hardware-in-the-loop testing (HIL) and to model-based control strategies.
To define theoretical models for control-oriented applications, an original library has been built up in Matlab®/Simulink® environment for the simulation of the intake and exhaust systems of automotive turbocharged engines.
Starting from this library, a Mean Value Model (MVM) of a Diesel engine, with variable-geometry turbocharger (VGT), EGR and throttle valve, has been defined and fitted on a small automotive application. The model allowed to simulate in “real-time” engine behaviour: calculated and experimental data are reported and compared in the paper showing a good agreement both in steady and transient operating conditions
A switching Moving Boundary Model for the simulation of ORC plants in automotive applications
No full textWaste heat recovery is a promising approach to improve fuel economy and emissions of thermal engines for stationary and mobile applications. Among recent solutions, Organic Rankine Cycles (ORC) seem to join effectiveness and technological readiness for the application to Internal Combustion Engines (ICE), both Spark Ignition (SI) and Diesel. Significant reductions in fuel consumption have been reported, but – especially in automotive applications – further improvements in the ORC plant matching and performance in transient operations are required. This paper presents a lumped-parameter model of an ORC system for exhaust waste heat recovery in automotive engines. The heat exchangers dynamics is accounted for by modeling the behavior of the working fluid through the Moving Boundary Method (MBM), which is based on a lumped-parameter representation of the conservation laws for single and two-phase fluid flows. An original switching technique has been implemented to account for variations in the fluid properties and heat transfer during transient operations of the ORC plant. Grey-box models for the pump and expander have been developed starting from steady-state characteristic maps. The behavior of the comprehensive model in transient operating conditions has been significantly improved also during start-up process, usually a threatening situation for mathematical models
Experimental Investigation on Surge Phenomena in an Automotive Turbocharger Compressor
No full textDownsizing and turbocharging are today considered an effective way to reduce CO2 emissions in automotive gasoline engines, especially for the European and US markets. In the broad field of research and development for engine boosting systems, the instability phenomenon of surge has gathered considerable interest in recent years, as the main limiting factor to high performance boosting and boost pressure control. To this extent, developing an in-depth knowledge of the surge dynamics and on the phenomena governing the transition from stable to unstable operation can provide very valuable information for the design of the intake system and boost pressure control algorithms, allowing optimal boost pressure without compromising the transient response. This paper describes an experimental study that aims at better understanding the phenomena leading to the inception of surge, and exploring the effects of the downstream circuit geometry on the compressor dynamic behavior in surge and prior to surge. A specific circuit adaptable in volume and length was designed to study the effect of different configurations on the steady flow compressor performance, with special reference to the surge line position. Instantaneous static pressures are measured in several locations upstream and downstream the compressor. Besides, dynamic sensors to measure noise and vibrations are also adopted. The preliminary results of the experimental campaign are presented, exploring the influence of geometry variations on the compressor map and surge dynamics
Model Order Reduction of the Doyle-Fuller-Newman Model via Proper Orthogonal Decomposition and Optimal Collocation
No full textNonlinear Model Predictive Control of an Organic Rankine Cycle for Exhaust Waste Heat Recovery in Automotive Engines
No full textEnergy recovery from exhaust gas waste heat can be regarded as an effective way to improve the energy efficiency of automotive powertrains, thus reducing CO2 emissions. The application of Organic Rankine Cycles (ORCs) to waste heat recovery is a solution that couples effectiveness and reasonably low technological risks. On the other hand, ORC plants are rather complex to design, integrate and control, due to the presence of heat exchangers operating with phase changing fluid, and several control devices to regulate the thermodynamic states of the systems. Furthermore, the power output and efficiency of ORC systems are extremely sensitive to the operating conditions, requiring precise control of the evaporator pressure and superheat temperature.
This paper presents an optimization and control design study for an Organic Rankine Cycle plant for automotive engine waste heat recovery. The analysis has been developed using a detailed Moving Boundary Model that predicts mass and energy flows through the heat exchangers, valves, pumps and expander, as well as the system performance. Starting from the model results, a nonlinear model predictive controller is designed to optimize the transient response of the ORC system. Simulation results for an acceleration-deceleration test illustrate the benefits of the proposed control strategy
Model-order reduction for wave propagation dynamics in internal combustion engine air path systems
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
- …
