A Zero-Dimensional Two-Phase Model of the Thermal Transient of an I.C.E. Cooling System after a Rapid Switch-off

The paper illustrates a zero-dimensional dynamic model which was developed in the MATLAB^®/Simulink environment to predict thermal transient of an automotive cooling system.

In particular, the rapid switch-off of an internal combustion engine which was operated for a prolonged time at high speed under full load was investigated. In this condition, significant vapour formation and, consequently, pressure rise within the cooling circuit can arise, because of the sudden heat transfer from the high temperature head metal to the coolant contained in the cylinder head passages. The proposed model allows predictions of the vaporized mass of coolant as well as of the pressure evolution within the cooling circuit.

The simulations results were compared with experimental tests carried out on a production 4-cylinder, MPI small S.I. engine, 1.2 dm³ displacement, and the agreement was very satisfactory.