Transport of people and freight on-road have a big impact on the total energy use in the world. The majority of these transports is propelled with diesel engines and the reason is simply that the diesel engine is better than the gasoline engine due to lower fuel consumption. But the cost of this is the increase in dangerous nitrogen oxides (NOx). Around 10 000 people dies every
year due to emissions emitted by diesel engines and the majority is caused by NOx emissions. If new technology could be applied and improve today’s exhaust after-treatment systems, more than 174 000 lives can be saved by year 2040. This thesis focuses on a technology developed by Swedish Biomimetics 3000 in cooporation with Lund University. The technology is novel in it’s way to introduce small pre-heated droplets into the stream of exhaust gases and this
method is inspired by nature. These droplets evaporate a lot faster compared to the standard system’s today. Tests have shown that this new technology is able to reduce the NOx emissions and at the same time reduce the unwanted slip of ammonia through the catalyst. To further reduce the total NOx emitted during the full engine up-time the catalyst needs to be warmed-up faster and enable high NOx-conversion earlier. The pre-heated droplets don’t lower the exhaust temperature as much as today’s standard systems and does not require as
high light-off temperature.
Results from this investigation shows that high conversion rates are possible already at temperatures below 200◦C. The reason is mainly due to the 87% reduction in droplet sizes. An effect of this is also that the total conversion rate can be increased drastically. This technology can be used on both heavy-duty and light-duty vehicles. The enhanced evaporative process has also show that the flow restricted mixer functions can be reduced which then lowers the back-pressures and the engine can be operated more efficiently. This leads to a reduction of CO2 as an GHG-emissions due to the reduction in fuel consumption.