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 performance and emission characteristics of diesel engines were systematically investigated in order to improve their design and operations. A fourstroke diesel engine with a displacement volume of 3856 cc was employed as the test engine. The intake air was conditioned to various temperatures and humidities via an air-conditioner before entering the intake port of the engine. This study shows that the air consumption rate, brake torque, and nitrogen oxides decrease, while the brake specific fuel 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 dioxide emissions are more significant at a higher temperature of the charge air. Furthermore, charge air temperature tends to increase the percentage of C02 in the exhaust while decreasing the percentage of excess oxygen.