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In order to evaluate the ventilation characteristics of car interior, a model experiment was performed. Part 1 deals with the air flow properties in a half-scale car model. In this paper, a trace gas experimental method equipped with Flame Ionization Detector (FID) systems is introduced to examine the local ventilation efficiency and inhaled air quality in the car, which was ventilated at a flow rate of 100 m3/h and kept in an isothermal environment of 28°C in the experiment. Here, ventilation efficiency was evaluated by means of the Scales for Ventilation Efficiencies (SVEs), and inhaled air quality in terms of the influences of passive smoke and foot odor was evaluated by means of the Contribution Ratio of Pollution source 1 (CRP1). Therefore, calculation methods using trace gas concentration values were suggested for these indices, which were proposed based on the Computational Fluid Dynamics (CFD) technique.

CFD has been actively applied for developing automotive air conditioning system in recent years. In addition to automobile interior air conditioning, an automotive air conditioning system has the important function of providing a clear field of view by defogging (or defrosting) the windows. Although many CFD application methods have been reported for estimating windshield defogging pattern, few examples of simulation show accurate result of transient clearing pattern. To predict transient clearing pattern accurately, using a correct model of window glass fogging-clearing is important. As the result of our observation on fogged glass surfaces, fogging was found out to be an aggregation of water drops, so that new dropwise condensation-evaporation model was developed and applied. Transient defogging patterns were simulated with the CFD code including this model, and accuracy was verified on a simplified compartment model and actual automobiles.