New model of gasoline combustion developed using experimental data

May 30, 2017, King Abdullah University of Science and Technology

By observing the soot particles formed in a simple flame, researchers at KAUST have developed a computational model capable of simulating soot production inside the latest gasoline automobile engines.

Although today's passenger vehicle engines are cleaner than ever before, their exhaust can still contain significant numbers of nanoscopic that are small enough to penetrate the lungs and bloodstream. This new computer should help improve their engines to cut formation.

Gasoline engines are not traditionally associated with soot—it's a problem usually linked with diesel vehicles. But over the last decade, to boost efficiency, manufacturers have made their gasoline engines more diesel-like, adopting "direct injection" technology that sprays fuel directly into the cylinder.

"Sometimes you get fuel-rich pockets where there's not enough air for complete or sometimes the fuel hits the cylinder wall and forms a pool fire," said S. Mani Sarathy from the KAUST Clean Combustion Center, who co-led the work. Both of these scenarios generate soot.

Working out how to minimize soot is a challenge because it is difficult to see inside an engine cylinder as fuel combustion takes place. Sarathy and his coworkers tackled the problem by burning a chemically simplified "gasoline surrogate" mixture in an experimental setup called a counterflow diffusion flame. By shining lasers into this open flame, they could monitor soot and its precursors as the fuel burns. "These experiments have been done previously with gaseous fuels, but this is the first time they have been done with gasoline-relevant liquid fuels," Sarathy said.

The team varied the composition of the fuel and observed particle production to build a model of the basic chemical reactions through which soot particles form and grow. "Once we have this basic kinetic model that works well in simple flames, we can utilize the model in an engine simulation," Sarathy explained. An engine combustion simulation is essentially an ensemble of many tiny flamelets, which are combined to give a complete picture of how soot is formed in an engine.

Car makers could use Sarathy's model in their own simulations to test whether changes, such as altering engine geometry or the timing of fuel injection, might cut soot production. "We also have industrial partners that utilize the model to see how different fuels and engine combustion strategies affect soot production," Sarathy said.

Explore further: Carcinogenic soot particles from petrol engines

More information: Sungwoo Park et al. Compositional effects on PAH and soot formation in counterflow diffusion flames of gasoline surrogate fuels, Combustion and Flame (2017). DOI: 10.1016/j.combustflame.2017.01.001

Related Stories

Carcinogenic soot particles from petrol engines

May 24, 2017

A new study led by Empa scientists finds that some direct-injection gasoline engines emit just as many soot particles as unfiltered diesel cars did in the past. Particle filters can remedy this.

Cleaner diesels thanks to laser light

December 7, 2007

Dutch researcher Bas Bougie has developed a laser system to investigate soot development in diesel engines. Small soot particles are not retained by a soot filter but are, however, more harmful than larger soot particles. ...

Less is more when it comes to soot

April 5, 2016

Small particles emitted into air during the burning of hydrocarbon fuels damage the human respiratory system and enhance the greenhouse effect. In their agglomerated form, these particles form soot that consists predominantly ...

Is it safe to breathe yet?

April 26, 2010

Anyone who has ridden behind a truck belching black exhaust knows the smell and discomfort caused by soot, the airborne carbon particles that result from the incomplete combustion of hydrocarbons such as diesel fuel. Those ...

Recommended for you

Printing microelectrode array sensors on gummi candy

June 22, 2018

Microelectrodes can be used for direct measurement of electrical signals in the brain or heart. These applications require soft materials, however. With existing methods, attaching electrodes to such materials poses significant ...

EU copyright law passes key hurdle

June 20, 2018

A highly disputed European copyright law that could force online platforms such as Google and Facebook to pay for links to news content passed a key hurdle in the European Parliament on Wednesday.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.