1. Theoretical cycles

Before describing the zerodimensional modeling approach, this section reviews some basic notions about the qualification of cycles and, more specifically, theoretical cycles.When modeling an engine cycle using theoretical thermodynamic evolutions, it is conventional to break it down into 5 phases: intake, compression, combustion, expansion and exhaust. Each cycle sequence can be modeled by thermodynamic evolutions in reversible adiabatic, isentropic or polytropic states, at constant volume, pressure or temperature, or by sudden expansion. The combustion phase itself can then be broken down into elementary isochoric, isobaric and isothermal phases, referring to the Carnot, Beau de Rochas and Diesel cycles. The term cycle is not entirely appropriate in the context of real internal combustion engines, since gases do not undergo a cycle in the thermodynamic sense. In theoretical studies, the...