Impending legislation will make it almost inevitable that heavy-duty trucks will have to be fitted with some form of particulate removal after-treatment device. The challenge is to provide a system that is not only environmentally acceptable and cost effective but also durable enough to meet the demands of the trucking industry. Diesel particulate filters (DPF), in conjunction with fuel borne catalysts to facilitate regeneration, are now a recognised technology for meeting future passenger car emissions limits.
Retrofitting of such systems to older technology vehicles, where specific environmental concerns exist, has demonstrated the possibility of applying this technology to the heavy-duty vehicle sector. Most of these retrofit applications tend to be to vehicles with a relatively low duty cycle. Whereas this type of duty cycle poses the greatest challenge to the successful regeneration of the filters it is not necessarily the most arduous test of the durability of the system.
To demonstrate the efficacy of the DPF additive system to a wider application range, five heavy-duty trucks were fitted with DPFs and onboard additive dosing systems. Three different DPF technologies were used and two different additive technologies. A sixth truck was also included in the trial as a reference. The trucks routinely travel in excess of 10,000 km per month. Regular sampling of the lubricating oil is used to check for adverse effects on engine durability whilst on board data logging of filter temperatures and pressures are used to monitor the performance of the filters.
This paper presents details of the installation of the systems as a direct replacement for the existing vehicle silencer, details of the effect of the filters on the regulated emissions, plus information from the onboard data logging system. The conclusion drawn is that, to date there are no indications of any problems with the durability of the DPF systems.