Intake Valve Temperature Effect on the Mixture Preparation in a SI Engine During Warm-up

다국어 초록 (Multilingual Abstract)

A heat transfer model of the intake valve in a spark ignition engine is presented, which is cali-brated with a number of the valve temperature profiles measured druing engine warm-up for the gaseous fuel(propane). The valve is divided into four identical elements for which the assumption of lumped thermal mass is applied. The calibration is made so that the difference between the measured and simulated valve temperatures becomes minimal. Then, the model is applied to the cases of the liquid fuel(indolene) to estimate the amount of the liquid fuel vaporized from the in. take valve by assuming that fuel evaporation accounts for the deficit of the heat balance budget. The results of the model show quantitative contribution of each heat transfer source to the heat bal-The behavior of the calculated mass fraction of the fuel vaporized from the intake valve ex-plains how the liquid fuel evaporates during engine warm-up, indicating the important role of the intake valve during the early stage of engine warm-up. The mass fraction at warmed-up condi-tions is closely related with the fraction directly targeted on the valve back by the fuel spray geom-etry.<br/>