Aim
The objective of the course is to provide a thorough understanding of the processes that occur in an internal combustion engine and the reason why it is designed as it is.

Knowledge and understanding
For a passing grade the student must

be able to give an overview of the functions of main components of a modern combustion engine as well as how they have evolved over time
• be able to provide an individual written explanation of the combustion processes in spark ignition and compression ignition engines and how they are influenced by various operating and design parameters at a detailed conceptual level

• be able to perform stoichiometric analysis of combustion of any hydrocarbon fuel with air

Skills and abilities
For a passing grade the student must

be able to use mean effective pressures and other characteristic engine parameters to analyse combustion engines, select an engine type and design the engine (in terms of displacement volume, number of cylinders, cylinder bore and engine speed) for a given simple application
• be able to calculate the air/fuel ratio given a measured exhaust composition as well as the air requirement for complete combustion of any hydrocarbon fuel

• be able to apply ideal thermodynamic cycles in order to calculate efficiency and mechanical work for combustion engines and relate the results to real thermodynamic cycles

• be able to, groupwise with supervision, disassemble and reassemble a modern combustion engine as well as conduct performance and emission measurements on it

Judgement and approach
For a passing grade the student must

• actively participate in discussions of relevant problems for the subject

• be able to present written analysis of combustion engine performance and emission measurements

Contents
The course mainly deals with combustion engines having internal combustion. First a general description of the most common engine types is given. The spark ignition and compression ignition principles are explained and the difference between two and four stroke engines is discussed. A brief coverage of two alternatives, the Wankel and Stirling engines is presented. The history of the internal combustion engine is presented. The early history is full of more or less successful trials to make an energy converter for gaseous or liquid fuels. Thereafter, a number of definitions of mean effective pressure and efficiency are explained. The coupling between the power requirement of a normal vehicle and the power produced by an engine is explained. The fact that all passenger cars have excessive displacement volume should be obvious here and possible ways to improve the situation are discussed. The general conversion of fuel to CO2, H2O and heat is discussed and stoichiometry is explained. Also, exhaust gas analysis is discussed in some detail. Ideal thermodynamic cycles are presented and used to explain the effects of compression ratio on fuel efficiency. The combustion process in the spark ignition engine is presented. Cycle to cycle variations in the combustion process are explained and abnormal combustion, "knock", is discussed. The exhaust emissions generally and from the spark ignition engine are explained, including the principle of cleaning with the three way catalyst. The diesel engine combustion process is presented both with the classical model and the newer Dec model. The emissions from the diesel engine are also discussed. Finally the various fuels, both contemporary as well as future fuels, are presented.

The course contains lectures, seminars, exercises and two laboratory exercises. In the first a modern four cylinder SI engine is disassembled and assembled and in the second a diesel engine is run and emissions are measured. Normally an industry representative will give an invited lecture.

Literature
Johansson, B, Förbränningsmotorer ("Internal Combustion Engines"), Avd för Förbränningsmotorer, LTH, and material handed out by the division.