There have been enormous technological advances ever since the industrial revolution and these have affected and influenced almost every aspect of society. The transport sector in particular has seen enormous changes over the years, and technological progress with regard to motor vehicles in particular has had major impacts. In today’s world, whilst concepts such as ‘value’ matter immensely to consumers, the real keystones are emissions and economy.
This has had some dramatic effects and the whole pattern of vehicle usage has changed quite dramatically. One of the major areas in this regard is diesel engines. Once the preserve of heavy goods vehicles and big coaches, the diesel engine has found a place in normal passenger cars due to its combination of fuel economy, potential performance, and reliability. The proportion of diesel-powered cars on the roads throughout Europe in particular has grown beyond anyone’s expectations over the last twenty or thirty years and diesel vehicles now account for some 30 per cent of sales.
The diesel engine offers many benefits, the biggest of which is its ability to produce comparatively high power outputs for relatively low fuel consumption. As a result, overall exhaust gas emissions are favourably low. However, there is one particular issue with diesel emissions, which is particulates. Diesel fuel tends to burn incompletely and produce carbon in relatively large quantities. This is discharged in the engine exhaust system in the form of soot particles, which are not only unpleasant but are known to have potential health issues.
Laws passed in various countries worldwide are aimed at reducing emissions from vehicles, and one aspect of these is to target particulates. Accordingly, manufacturers have looked into various methods and most have added a Diesel Particulate Filter (or DPF) to car and truck exhaust systems. Put simply, a DPF is a basic mechanical filter that merely removes soot particles from the exhaust gas.Of course, there are downsides to this. The main issue is that the filter becomes loaded with carbon particles relatively quickly and unless there is a method of cleaning the filter, it soon becomes blocked to the extent of causing engine damage and massively affecting performance. For passenger vehicles, the method of ‘regeneration’ involves driving the vehicle at comparatively high speed for a period of time, which results in the filter becoming hot enough to burn off the accumulated deposits.
Anyone ‘thinking outside the box’ will quickly come to the conclusion that whilst there are obvious benefits to removing particulates from diesel exhaust gas, using a DPF has inherent disadvantages. Firstly, the use of a filter on its own reduces efficiency, as it forms a barrier to exhaust flow and therefore reduces efficiency and increases fuel consumption. Secondly, and more importantly, having to run the vehicle at higher speeds to burn off the deposited carbon is inherently wasteful and the end…