Abstract
Air pollution by automobile exhaust gases is still a serious problem. In order to reduce air pollution caused by automobiles, the emission characteristics of the idling-mode and the reduction of exhaust gas emissions achieved by stopping the engine were investigated. Seven gasoline fueled vehicles and 13 diesel fueled vehicles were tested under the transient test cycle and idling-mode test. The results are as follows:
1. Emission rates (mg/s) and fuel consumption rates (mL/s) were compared between the transient test cycle and idling-mode. In the gasoline vehicles, the idling-mode fuel consumption was 47% of the transient cycle fuel consumption. In the gasoline vehicles equipped with a three-way catalyst, the concentration of NOR emitted during the idling mode was very low. In the diesel vehicles, the idling-mode emissions were 30% of the transient cycle NOx emissions, and the idling-mode fuel consumption was 28% of the transient cycle fuel consumption.
2. Although the amount of exhaust gases slightly increase when an engine is restarted, we confirmed that stopping the engine for a short time (from several seconds to a few minutes) reduced the fuel consumption of the gasoline vehicles and the amount of all exhaust gases of the diesel vehicles.
3. These results were applied to the operation of light-duty diesel trucks in Tokyo. In this case, it was estimated that the emissions contributed during the idling mode consist of 3.5% NOx, and 3.1% CO2 As a result, it was suggested that parked idling vehicles should be investigated as an emission source.
