The Regeneration of Diesel Particulates Filter (DPF) with Hydrogen 2013-01-0090

Diesel engines possess high energy efficiency as for power generation, and they have been used in commercial vehicles widely for a long time. Due to the coming shortage of fossil fuel in the near future and the impact of greenhouse gas effect in recent years, the types and quantities of diesel vehicles have grown year by year. However, smoke emission of diesel engine has always been an issue. Diesel smoke can be seen by eyes apparently, and it becomes an obvious pollution problem.

Traditional diesel particulate filter (DPF) is the current solution to solve the problem of smoke emission currently. However, after using DPF for a certain period of time, the back pressure of engine will rise up and the engine performance will be affected because of the accumulation of soot particles. The soot particles must be removed. This process is the regeneration of DPF. Generally, diesel fuel is injected into exhaust pipe, and with the help of an oxidation catalyst (DOC), diesel fuel can be burned, and the exhaust temperature is raised to the point that the soot particles accumulated in DPF can be ignited. But the regeneration system is very complicated, and the cost of DPF is high. Besides, to maintain enough exhaust temperature, the engine must be operated at high load during regeneration. As a result, the regeneration process can be carried out at limited engine running conditions, and penalty in fuel consumption may occur.

This study is to present a set of hydrogen regeneration systems making use of the characteristics of wide range of inflammability and high heating value to substitute for diesel regeneration system. The advantages of hydrogen regeneration system are simplicity and high efficiency. It doesn't need a DOC and the cost is reduced. Moreover, the temperature is high and duration is short, and the process can be conducted at any engine condition, including idle.

A Hino W06E diesel engine was used in this study for testing. It was operated at idle to conduct the generation process. The exhaust temperature was only 77°C. By providing 170 L/min of hydrogen, the exhaust temperature could be raised up to 700°C in front of DPF, and the rear temperature was also up to 520°C, reaching the ignition tem soot particles. The whole regeneration process could complete within 10 minutes, and 96% of soot particles have been removed.