Handout of courses Internal Combustion Engine

Abstract

This course is intended for third-year undergraduate students (LMD system) specializing in Mechanical Construction. It is designed to provide students with the knowledge and methodological tools required to carry out thermodynamic analysis and synthesis studies of internal combustion engines. The course content has been developed in accordance with the official curriculum of the sixth semester of the third-year undergraduate program in Mechanical Construction. Internal combustion engines are among the most important technological achievements in modern mechanical engineering. They are widely used in transportation, industrial applications, power generation, agriculture, and marine systems due to their ability to efficiently and reliably convert the chemical energy of fuels into usable mechanical energy. The study of internal combustion engines integrates several engineering disciplines, including thermodynamics, fluid mechanics, heat transfer, combustion science, machine dynamics, and materials engineering. This handout is designed for 3rd Year undergraduate mechanical engineering students, particularly those studying engine technology and power conversion systems. It provides a comprehensive introduction to the fundamental principles, operating characteristics, thermodynamic cycles, and mechanical behavior of internal combustion engines. The course aims to develop the theoretical understanding and practical knowledge necessary for the analysis, design, operation, and maintenance of modern engines. The first chapter begins with an overview of internal combustion engines and their classification according to ignition method, fuel type, number of strokes, cooling system, and application. Particular attention is paid to the operating principles of spark-ignition (SI) and compression-ignition (CI) engines, which represent the two main categories used in the automotive and industrial sectors. Chapter 2 includes a detailed analysis of thermodynamic cycles, including the Beau-de-Rochas (Otto) cycle, the Diesel cycle, and the Sabatier cycle. These ideal cycles are analyzed to understand the energy transformation within the cylinder and to evaluate engine performance using parameters such as thermal efficiency, compression ratio, pressure, temperature, and heat transfer. The study also presents real engine cycles and compares them with theoretical models to highlight the practical limitations resulting from energy losses during combustion, friction, heat dissipation, and incomplete gas exchange processes. Chapter 3 details the actual operating cycle of diesel engines through the four basic stages: intake, compression, combustion and expansion, and exhaust. The chapter presents diagrams and key engine characteristics to help students understand engine behavior under various operating conditions. It emphasizes the relationship between theoretical analysis and practical engine performance. Chapter 4: Dynamics of Reciprocating Engines. This chapter examines the kinematic and dynamic analysis of the sliding crankshaft mechanism, connecting rod motion, balancing of rotating and reciprocating masses, and valve timing systems to understand vibration phenomena, mechanical stresses, and power transmission within the engine. These concepts are fundamental to improving engine durability, smooth operation, and efficiency. Chapter 5 addresses engine performance parameters, such as indicated power, braking capacity, torque, specific fuel consumption, volumetric efficiency, and thermal efficiency. Engine characteristics are analyzed under full and partial load operating conditions according to international standards. The impact of fuel properties, combustion quality, and ignition systems on engine operation is also presented. The objective of this handout is therefore to provide students with a solid scientific and technical foundation in internal combustion engines, and to prepare them for advanced studies and professional applications in automotive engineering, energy systems, manufacturing industries, and research fields related to thermal machinery and sustainable energy technologies.