The idea of a ‘cool flame’ sounds contradictory. It exists, however, and it holds the key to creating better diesel engines. Scientists first discovered the concept of cool flames during the early 19th century, but researchers have only recently realised its potential in improving diesel combustion. Engineers from the Sandia National Laboratories are, in fact, performing direct numerical simulations to understand how the flame can make diesel engines work better and reduce emissions.

1. Scientists Improve Diesel
Engine Efficiency by
Understanding Cool
Flame Properties
Diesel Dog

2. The idea of a ‘cool flame’ sounds contradictory. It exists, however, and it holds the key to creating
better diesel engines. Scientists first discovered the concept of cool flames during the early 19th
century, but researchers have only recently realised its potential in improving diesel combustion.
Engineers from the Sandia National Laboratories are, in fact, performing direct numerical
simulations to understand how the flame can make diesel engines work better and reduce
emissions.
Cool Flames Lead to Better Fuel Economy
Using the adjective ‘cool’ to describe the flames is only relative. While it has a lower temperature
and produces less heat than conventional flames, it burns at less than 1,150° Kelvin (1,610°F). In the
study, the researchers tried to figure out the influence of cool flames during the ignition and flame
stabilisation process—an important finding that could help create efficient and cleaner-burning
engines in the future.
Unlike gasoline engines that use a spark plug to ignite a fuel-air mixture, diesel engines require
performing the autoignition process. After injecting the fuel into the engine, rapid mixing and
combustion work hand-in-hand to drive the engine. While the process only lasts for a fraction of a
second, the researchers believe that cool flamescan help improve engine efficiency.

3. Using Simulations to Study Diesel Combustion
The team discovered that cool flames speed up the formation of ignition kernels. Understanding
how the kernels propagate the fuel-air mix can help engineers design diesel engines that allow for
the complete combustion of fuel. Knowing how and when the flames begin is important information
that could ensure complete combustion.
Combustion is a difficult process to study because of the complex properties of fuel. The researchers
state that only a realistic simulation of diesel combustion can help capture the process accurately in
a way that could help researchersenhance the efficiency of existing diesel engines. While further
studies are still underway, improving diesel fuel productivity with a fuel filter is a good enough
alternative. Filter kits guarantee long-term protection for diesel equipment, after all.

4. Sources:
https://www.sciencedaily.com/releases/2017/10/171012200226.htm
http://dieseldog.net.au/
http://www.machinedesign.com/mechanical/simulating-combustion-improves-diesel-engines
https://www.engineering.com/DesignerEdge/DesignerEdgeArticles/ArticleID/15863/Direct-
Numerical-Simulation-of-Cool-Flames-for-Diesel-Combustion.aspx