Diesel emissions are 90% lower than they were in the 1980s; however exhaust regulations based on statistical studies dealing with the health impact of exhaust emissions continue to demand even lower gaseous and particulate diesel emissions. Particulate emissions are responsible for the characteristic black exhaust fumes emitted from the diesel engine. They are a complex mixture of solid and liquid components with the majority of particulates being carbon microspheres on which hydrocarbons from the engines fuel and lubricant condense.
In order to comply with the strict European Stage IV emission standard, which now stipulates a further 50% reduction in particulate emissions, an exhaust emission control system is used on the XJ 2.7 liter and S-TYPE 2.7 litre diesel vehicles. The primary component of the system is the diesel particulate filter (DPF), which has been proven to be effective in reducing particulate emissions to negligible levels. The main ability of the particulate filter is its capacity for regeneration; that is burning the particulates trapped in the filter at calculated intervals in such a way that the process is unnoticed by the driver of the vehicle.
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