With millions of long-haul trucks shipping products across the nation, fuel efficiency is important. Luckily, diesel engines are, in general, more efficient than gasoline engines, but they are not perfect, especially when considering their exhaust. Researchers at Sandia National Laboratories have recently analyzed diesel engines and developed some ways to improve their efficiency while reducing the pollutants in their exhaust.
To increase efficiency, the researchers worked on a low-temperature combustion (LTC) strategy. This strategy recirculates some exhaust back into the engine, where it absorbs heat from the combustion process. By reducing the combustion temperature, the engine also reduces the amount of nitrogen oxides and particulate matter that are formed, but the amount of carbon monoxide and unburned hydrocarbons increase. This, the researchers found, is due to regions where there is too little fuel mixed with air, so they added post-injections to increase fuel concentrations. This in turn improves efficiency as less fuel is left unburned.
The hope for this research is that engine designers will be able to use it to develop better, more efficient engines. Given the cost of diesel currently, I suspect many of those designers will be eager to study the results.
Source: Sandia National Laboratories