Operating Principles

Abstract

Abstract All types of internal combustion engines (ICEs) have a working chamber limited by rigid walls, with one movable wall to enable volume changes; this is usually accomplished by a piston. Power is produced by the volume change, which in turn is generated by the variable gas pressure of the working volume in the cylinder. Different strategies can be applied to manage the processes as efficiently as possible for different applications. This chapter classifies the different working principles used in existing ICEs and also briefly describes about possible future concepts. The classification includes an overview of spark‐ and compression‐ignition combustion principles and alternative concepts such as homogeneous charge compression ignition (HCCI) combustion. ICEs are most conveniently described and classified by way of certain characteristic design properties and performance measures, which allow for quantitative comparisons. This chapter defines the most common characteristic properties of ICEs, such as the compression ratio, the air/fuel ratio, and various efficiencies. In particular, the section on ICE efficiency provides a general formulation of efficiency that expresses all relevant efficiencies in one equation. The chapter ends with the description of some widely used metrics specific to ICEs, including mean effective pressures, specific fuel consumption, and mean piston speed. Finally, some examples of typical engine maps and tables are given.