Simultaneous Reduction of HC, NO _x and PM by Using Active Regeneration Technique

Exhaust after treatment devices in diesel engines play a crucial role in control of harmful emissions. The noxious emission released from diesel engines causes a variety of problems to both human beings and the environment. The currently used devices are implemented with new catalyst technologies like DOC, SCR and catalytic converter are all designed to meet stringent emission regulations. Although these devices have considerable conversion efficiency, they are not without drawbacks. The catalysts used in these devices are rarely available and are also very expensive. Diesel Particulate Filter (DPF) is the device currently employed to collect particulate matter. It also has drawbacks like high back pressure, thermal durability restrictions, regeneration issues and poor collection of smaller size particles. In the case of biodiesel these fine sized particles are emitted in larger quantity. Another issue is that soot and other particulates collected on the surface of the catalyst cause catalyst poisoning and reduce the conversion efficiency of the catalyst. This paper presents a new technology that was developed to reduce HC, NO_x, and PM emissions simultaneously. A device was developed and its functioning was based on the concept of electrostatic precipitator and ozone generation by corona discharge technique. The device was fabricated and tested under various engine operating conditions. The test results showed a significant reduction in the percentage of HC, NO_x, and PM (60%, 70%, and 85%) under high load conditions. The device produced less back pressure compared with DPF besides addressing the regeneration problems. The fabricated trap showed good filtration efficiency when tested with biodiesel.