INFLUENCES OF CHARGE AIR HUMIDITY AND TEMPERATURE ON THE PERFORMANCE AND EMISSION CHARACTERISTICS OF DIESEL-ENGINES

The effects of humidity and temperature of intake air on the performan ce and emission characteristics of diesel engines were systematically investigated in order to improve their design and operations. A four-s troke diesel engine with a displacement volume of 3856 cc was employed as the test engine. The intake air was conditioned to various tempera tures and humidities via an air-conditioner before entering the intake port of the engine. This study shows that the air consumption rate, b rake torque, and nitrogen oxides decrease, while the brake specific fu el consumption, carbon monoxide, and sulfur dioxide increase with both the temperature and humidity of the charge air. However, the effects of the humidity on the formation of the carbon monoxide and sulfur dio xide emissions are more significant at a higher temperature of the cha rge air. Furthermore, charge air temperature tends to increase the per centage of CO2 in the exhaust while decreasing the percentage of exces s oxygen.