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Air Quality Modeling Working Group developed two models to evaluate effects of automobile emission reduction measures on air quality improvement: Urban Air Quality Simulation Model in which secondary aerosol formation processes have been incorporated, and Roadside Air Quality Simulation Model in which micro-scale traffic flow has been taken into consideration. Concretely, a model has been built up for estimating SPM concentration in ambient air in which high concentrated air pollutants have been contained during summer and winter. The model has been built up by using UAM (Urban Airshed Model) as base model, and the following modification has been made to the base model. First, ISSOROPIA (secondary inorganic aerosol equilibrium model) has been added to the base model, and a secondary organic aerosol formation/reaction model (SOA model) has been incorporated into the model.

Comparing with the previous Auto/Oil programs, the total plan and current status of the air quality modeling study in JCAP are presented. The total plan of air quality modeling study has the following characteristics: 1) Vehicle emission inventory program is developed by considering the original features of Japan. 2) Not only the urban air quality but also the road sides pollutants dispersion is evaluated. 3) The chemical reaction model for the secondary particulate formations is developed on the basis of the smog chamber experiments. 4) For the cost-effectiveness analysis of vehicle/fuel technologies, the output of the air quality modeling will be combined with the cost data of new vehicle emission reduction technologies As the first step, preliminary modeling studies are conducted to understand the overall tendency of the air quality change toward 2010 in Tokyo urban area.

Thermal efficiency of carbureted and injection engine was compared through thermodynamic cycle simulation. When the compression ratio is the same, the combined control carbureted engine in which the A/F ratio control method is used in the high load range and the throttling method is used in the low load range shows the highest thermal efficiency followed by the injection engine and the throttling carbureted engine. The thermal efficiency of the injection engine is lower than that of combined control carbureted engine because the temperature of gases in cylinder does not rise much due to stratified charge combustion. When the compression ratio of these engines is optimized, the thermal efficiency is the highest for the injection engine followed by the combined control carbureted engine. The thermal efficiency of the combined control carbureted engine is lower than that of the injection engine at high and low loads, but they are in the same level at intermediate loads.