Using new optical-diagnostic techniques, Sandia combustion researcher Mark Musculus and his colleagues identified the sources of key pollutants from LTC engines. Understanding how LTC works as a combustion technique may lead to broader use of cleaner diesel engines. (Photo by Dino Vournas)

Combustion Research Facility lead author, Mark Musculus, along with Sandia researchers Paul Miles and Lyle Pickett, through their latest research paper, “Conceptual models for partially premixed low-temperature diesel combustion,” in Progress in Energy and Combustion Science hope to communicate the details of how LTC works to the broader engine research community. This research and data provides a necessary science base for auto and engine manufacturers to build the next generation of cleaner, more fuel-efficient engines using LTC.

While LTC helps reduce particulate matter and nitrous oxides pollution, it isn’t without its own problems. Carbon monoxide (CO) and unburned hydrocarbons (UHC) pollutants increase. Both are not only toxic, but also reduce fuel efficiency. Using new optical diagnostic techniques, the CRF research team identified these LTC engine emission sources. In a breakthrough measurement, researchers used two-photon laser-­induced fluorescence to map in-­cylinder CO, a difficult measurement that had never been achieved inside a diesel engine.

With this new understanding of UHC and CO emissions, Musculus and Sandia post-­‐doctoral researcher Jacqueline O’Connor found that adding post-­injections (smaller squirts of fuel after the main spray in just the right areas) extends the complete combustion zone over a larger region—leading to lower UHC and CO emissions while increasing engine efficiency. The increased efficiency also translates into lower CO2 emissions.

The Sandia work was completed for DOE-­EERE.

Read the Sandia news release.