A Mathematical Model of the Evaporation of the Oil Film Deposed on the Cylinder Surface of IC Engines

The present paper describes a calculation procedure aimed to evaluate the evaporative loss of the lubricating oil deposed on the cylinder surface of i.c. engines.

The model is based on the simultaneous solution of the diffusion and energy equations referred to the liquid/gas interface.

A parametric analysis has been carried out to investigate the influence of some variables on oil evaporative losses. The calculation results show that both cylinder surface temperature and lubricating oil composition are significant parameters. Conversely, the oil film thickness does not seem to play an important role in evaporative loss.

Furthermore, it has been ascertained that the lubricating oil evaporation is increased during the intake stroke.

In any event, the evaporative loss represents a small percentage (a few percentage points) of total oil consumption if the distillate fractions are not too much light.