The DPF's regeneration systems
The regeneration of diesel particulate filters require temperatures of 550-650 ° C. Such exhaust temperatures are achieved only near full engine load (eg when moving uphill or hard acceleration) and rarely presented during engine operation in town . To assist regeneration , can be used two techniques:
- reduction in the equilibrium temperature
- raising the temperature of exhaust gas
The first method is used in passive systems and the second in active systems.
Passive Systems:
The reduction in the equilibrium temperature on passive systems is accomplished by introducing a catalyst as part of the system, so as to accelerate the reaction of soot with the oxygen or the nitrogen dioxide. Three main directions apply in practice:
- Introduction of the catalyst in a separate device (CRT)
- Introduction of the catalyst on the filter surface
- Introduction of the catalyst in the form of an additive in the fuel
Active Systems:
The active regeneration systems increase the exhaust gas temperature to effect the thermal regeneration of soot . The exhaust gas temperature can be increased by the following two methods :
- Heating exhaust using any device such as electrical resistance , fuel burner etc.
- Increasing the combustion temperature with measures within the cylinder such as the exhaust recirculation , secondary injection fuel in common rail systems etc.