Università degli studi di Modena e Reggio Emilia

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Teachers

Enrico MATTARELLI

Overview

At the end of the course, the student should be able to master the fundamental thermo-fluid-dynamic aspects of design and calibration of any type of internal combustion engine

Admission requirements

Besides mastering the Italian language, the student should know:
Classification of ICEs (2/4 stroke, Spark Ignition / Compression Ignition, Naturally Aspirated / Supercharged, …)
Nomenclature and design of the main engine components (pistons, valves, injectors, crankshaft..)
Understand the main operations of a 4-stroke engine (compression, expansion, exhaust, intake)
Understand the differences between an ideal and a real thermodynamic cycle
SI and CI combustion fundamentals (qualitative understanding of what occurs within the cylinder)
Aftertreatment systems (3-way catalyst, Diesel particulate filter, SCR)
Fundamentals of engine control (load, injection, …)

Course contents

General aspects:
Brake engine parameters. Indicated parameters (mean effective pressures), efficiency parameters. Brake power formula.
Experimental characterization of the ICE: operating and performance parameters; performance maps. ICE-vehicle coupling
Cycle modeling
Thermodynamic cycles: Otto, Diesel and Sabathé Influence of compression ratio, thermal load and peak cylinder pressure on thermodynamic efficiency. Maximum temperature and pressure. Exhaust gas temperature
Modeling of the indicated cycle: intake/exhaust strokes, combustion (Wiebe function), heat transfer
The Atkinson cycle (NA engines): thermodynamic efficiency, influence on volumetric efficiency. The Miller cycle. Numerical examples of Miller and Atkinson engines
Review of engine concepts
Comparison between CI and SI engines. Comparison between 2 and 4-strokes. CNG and H2 engines. Innovative combustion concepts (HCCI/RCCI/prechamber)
Gas exchange process
Introduction to the gas exchange process in 4-stroke engines: expression of volumetric efficiency through the 1st principle of Thermodynamics. Influence of flow losses in the intake/exhaust system, heat transfer, fuel vaporization. Comparison between port injection and direct injection in SI engines. Modeling of the flow through the valves: effective area, discharge coefficients. The steady flow bench. Errors in the measure of effective area at the steady flow bench. Measure of the turbulence parameters (swirl and tumble). Formula of Swirl Ratio. Mean effective area, the Mach index. Numerical examples
Fundamentals of pressure waves Dynamic effects in SI high speed engines. Influence of number of cylinders and bore-to-stroke ratio on SI high speed engines
Valves actuation systems
Supercharging
Introduction to supercharging: general aspects, classification.
Mechanical and electric supercharging.
Introduction to turbocharging. Compressor and turbine maps. Calculation of the operating point on the map. The waste-gate valve. Design of the supercharging system with waste-gate. Variable geometry turbine, 2-stage systems. Evolution of turbocharged SI engines

Teaching methods

Standard class activity, in Italian, supported by PowerPoint presentations, released to students. Application of theoretical concepts to real projects by using simple spreadsheets (Excel) Class attendance is NOT mandatory, but it’s strongly recommended even if almost every subject is covered by handouts.

Assessment methods

There are no mid-term tests. The exam consists of a written test and an optional oral test, to be taken as part of the same session. At the end of the course, between June and September, there are at least three exam sessions. Only in the event of a greater number of exam sessions, in the aforementioned period, restrictions may be placed on the attempts available to students (maximum three) The written test will be held in presence. The written test consists in solving numerical exercises. The use of a calculator and a form, drawn up by the student, of no more than two sides of A4 sheet is always allowed. The sum of the scores of each question will be equal to at least 30/30. There are no penalties for the wrong questions, but, in the case of an incorrect numerical value, the evaluation will be at the discretion of the teacher. The results of the written test will be communicated by the teacher before the oral exam, in conjunction with the public correction of the written test. If in doubt, the assignments will be reviewed. At the end of the correction, it will be possible to communicate the willingness to access the oral or not, which allows an increase of maximum 2 points with respect to the mark of the written test. If the paper has had a positive evaluation, in the absence of other communications from the student, it means that the grade of the paper is accepted The oral exam will consist of at least two questions on any topic of the course.

Learning outcomes

1) KNOWLEDGE AND UNDERSTANDING
• Understand the main issues related to the design and calibration of internal combustion engines
• Understand which are the technological solutions and the most important tools to address the aforementioned problems
• Apply simple models to the study of different problems
• Analyze the results from numerical simulations or experimental investigations
• Evaluate pros and cons of each analyzed solution
• Create, when possible, solutions for the analyzed problems
2) KNOWLEDGE AND UNDERSTANDING APPLIED
• Ability to identify critical issues and strengths in the design and calibration of an internal combustion engine
• Ability to identify the most appropriate technologies to achieve the engine project objectives
• In-depth knowledge of all the main engine parameters
• Ability to calculate the aforementioned engine parameters on the basis of geometric and experimental data
• Ability to apply simple numerical models to the study of the indicating cycle
• Ability to set up the design of the intake and exhaust systems of four-stroke engines, including valves
• Ability to set up the design of a supercharging system
3) AUTONOMY OF JUDGMENT
• Ability to analytically compare different design solutions
4) COMMUNICATION SKILLS
Acquisition and mastery of the most important technical terms, both in Italian and in English
5) ABILITY TO LEARN
• Ability to deepen the basic knowledge acquired during the course through the consultation of textbooks, scientific articles, reports and participation in further courses, seminars, conferences
• Ability to understand the concepts taught in the more advanced courses on the same topic
• Ability to initiate a continuous learning process

Readings

Ferrari, D'Errico, Onorati: "Internal Combustion Engines", Società Editrice Esculapio, Bologna, 2022
G.A. Pignone, U.R. Vercelli: "Motori ad alta potenza specifica", Giorgio Nada Editore, Torino