Search Results

Experimental investigations were conducted with a direct-injection diesel engine to improve exhaust emission, especially nitrogen oxide (NOx) and particulate matter (PM), without increasing fuel consumption. As a result of this work, a new combustion concept, called Modulated Kinetics (MK) combustion, has been developed that reduces NOx and smoke simultaneously through low-temperature combustion and premixed combustion, respectively. The characteristics of a new combustion concept were investigated using a single cylinder DI diesel engine and combustion photographs. The low compression ratio, EGR cooling and high injection pressure was applied with a multi-cylinder test engine to accomplish premixed combustion at high load region. Combustion chamber specifications have been optimized to avoid the increase of cold-start HC emissions due to a low compression ratio.

Diesel exhaust contains a lower level of hydrocarbons, which serve as the reductant for the NOx catalyst, than gasoline engine exhaust. An investigation was made of several methods for maximizing the performance of NOx catalysts for direct-injection diesel engines. First, the catalysts were given an HC adsorption capability and then their characteristics were tailored to the HC species contained in diesel exhaust. This HC adsorption capability is designed to achieve better utilization of the HC species in diesel exhaust as a reductant. Second, catalyst performance was examined under passive and active conditions. Excellent catalyst performance was obtained under a passive condition, because at high engine loads, NOx catalysts with an HC adsorption capability can utilize HCs adsorbed under low engine load conditions to reduce NOx.

An electrically regenerable diesel particulate filter particularly suitable for small (less than 4.0 liters) diesel engines has been developed. The cartridge consists of a unique tubular heater which is wrapped with ceramic fibers. Two or more of these cartridges with integral heaters are used in building a diesel particulate filter system. The features of this cartridge are described along with performance results. Performance and durability data are presented under both steady state and transient operating conditions. System design using these cartridges in a forklift truck application is presented in this paper. Performance and durability data of the system is discussed.