Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sandia develops optical diagnostic to help improve fuel economy while reducing emissions

06.11.2017

New engine optics to fuel future research

A new optical device at Sandia National Laboratories that helps researchers image pollutants in combusting fuel sprays might lead to clearer skies in the future.


Sandia National Laboratories researchers Scott Skeen, left, and Lyle Pickett, center, and former Sandia researcher Julien Manin discuss a new optical device developed at Sandia that can quantify the formation of soot.

Credit: Dino Vournas

An optical setup developed by researchers at Sandia's Combustion Research Facility and the Technical University of Denmark can now quantify the formation of soot -- particulate matter consisting primarily of carbon -- as a function of time and space for a variety of combustion processes. Initially, the researchers have focused on the combustion of liquid fuel sprays found in engines, where the extreme pressures and temperatures create an environment that is optically challenging.

To meet future particulate matter emissions mandates without sacrificing fuel savings, engine developers need advanced combustion strategies to reduce the formation of soot in spray flames.

"The acquired data provides important insights into the fuel spray motion as well as the timing and quantity of soot formed under a wide range of conditions," said Sandia researcher Scott Skeen. "Engine developers can use this information to validate computer models and design advanced engine combustion strategies that will improve fuel economy for consumers while also lowering tailpipe pollutant emissions."

The work was published in an Applied Optics paper titled, "Diffuse back-illumination setup for high temporally resolved extinction imaging" and was selected as a "Spotlight on Optics" by the Optical Society in July. Authors included Fredrik Westlye and Anders Ivarsson from the Technical University of Denmark and Sandia researchers Keith Penney, Lyle Pickett and Skeen and former Sandia researcher Julien Manin. The work was funded by the Department of Energy's Vehicle Technologies Office.

High-speed diagnostics will shed light on future research

The optical setup was developed to quantify soot formation in high-pressure spray flames produced in Sandia's optically accessible, constant volume, pre-burn combustion chamber.

Imaging flames at temperatures and pressures found in engines can be difficult because of a phenomenon called "beam steering." Beam steering occurs when light passes through a medium with varying refractive indexes and is commonly observed as a "mirage" on the highway in the summer time. The hot pavement heats up nearby air, causing its refractive index to change. The sunlight changes direction as it passes from cooler air through hotter air, and these steered light rays give the impression that there is water in the road -- a mirage. In a similar way, a flame causes beam steering because of adjacent high- and low-temperature regions. The magnitude of beam steering increases significantly in an engine because of the high pressures. With optimized lighting and imaging optics, however, the effects of beam steering can be eliminated.

The special lighting was enabled by a custom engineered diffuser large enough to fill the area of Sandia's spray combustion chamber window (4 inches or 100 millimeters). The engineered diffuser was specifically designed to emit light rays with the same brightness over a specified angular range. In this way, a light ray that gets steered as it passes through the flame will be replaced by another ray having the same intensity.

The angle of the engineered diffuser is optimized based on the physical dimensions of the experimental facility, the magnitude of the anticipated beam steering and the collection angle of the imaging system. "In fact," Manin said, "without such a specific optical arrangement, quantifying soot via light attenuation in high-pressure spray flames, where beam steering is more severe, would not be possible."

Making cleaner engines

Skeen explains that although new diesel vehicles are cleaner than ever before, some of the latest generation gasoline engines emit as much particulate matter as older diesel engines. The increased particulate matter can be attributed to the adoption of a gasoline direct-injection fuel system, which results in improved fuel economy and therefore lower carbon dioxide emission per mile driven.

Gasoline direct injection involves spraying high-pressure liquid gasoline directly into the engine cylinder rather than mixing and vaporizing the fuel in the intake port outside the cylinder. This method reduces heat loss and allows for freer airflow. However, consumer savings at the pump come at the cost of higher particulate matter emissions. Unlike the much-maligned black smoke emitted from older diesel engines, soot emitted from gasoline direct injection engines is invisible to the naked eye because of the particles' very small size.

The diagnostic presented in the paper allows researchers to quantify the formation of particulate matter in combusting sprays with unprecedented temporal and spatial resolution. Insights gained and data acquired from the use of this diagnostic will inform and guide researchers and automotive manufacturers toward designs that maximize fuel efficiency while minimizing harmful tailpipe emissions.

A standardized method

The work is a significant contribution to the Engine Combustion Network established in 2010 by Pickett. The network promotes collaboration among engine researchers around the world. Although participation is voluntary and the network provides no financial support, more than 15 institutions have contributed experimental data.

"The network represents the power of a grass-roots movement," said Pickett. "We have accomplished 20 years' worth of research in one-fifth of the time."

One challenge of the wide-ranging collaborative effort within the network is the standardization of experimental diagnostics. "With so many researchers eager to participate, it is important to ensure that everyone contributes high-quality data acquired in a technically sound manner," said Pickett.

The optical technique developed in this work relies on light attenuation or extinction to quantify the amount of soot in a flame. As light enters the combustion vessel, it will be absorbed or scattered by soot particles. Light that is absorbed and some light that is scattered will not reach the camera sensor. This reduction in measured light intensity -- relative to a clear optical path -- can be related to the amount of soot present. To make implementation of this diagnostic tool convenient for network participants, the associated publication provides detailed guidance on the necessary equipment and instruction for sizing the illumination source and collection optics. The use of a Sandia-developed LED light source, as opposed to a high-speed laser, means the cost and complexity are significantly lower.

"This work aims to establish a standardized experimental method of extinction imaging that will increase the reliability and reproducibility of experimental measurements submitted to the network," Westlye said.

###

Sandia National Laboratories is a multimission laboratory operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy's National Nuclear Security Administration. Sandia Labs has major research and development responsibilities in nuclear deterrence, global security, defense, energy technologies and economic competitiveness, with main facilities in Albuquerque, New Mexico, and Livermore, California.

Media Contact

Michael Padilla
mjpadil@sandia.gov
925-294-2447

 @SandiaLabs

http://www.sandia.gov 

Michael Padilla | EurekAlert!

More articles from Power and Electrical Engineering:

nachricht Transparent solar technology represents 'wave of the future'
24.10.2017 | Michigan State University

nachricht Waste from paper and pulp industry supplies raw material for development of new redox flow batteries
12.10.2017 | Johannes Gutenberg-Universität Mainz

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

Im Focus: Support Free with “TwoCure” – Innovation in Resin-Based 3D Printing

The Fraunhofer Institute for Laser Technology ILT and Rapid Shape GmbH are working together to further develop resin-based 3D printing. The new “TwoCure” process requires no support structures and is significantly more efficient and productive than conventional 3D printing techniques for plastic components. Experts from Fraunhofer ILT will be presenting the state-funded joint development that makes use of the interaction of light and cold in forming the components at formnext 2017 from November 14 to 17 in Frankfurt am Main.

Much like stereolithography, one of the best-known processes for printing 3D plastic components works using photolithographic light exposure that causes liquid...

Im Focus: Researchers develop chip-scale optical abacus

A team of researchers led by Prof. Wolfram Pernice from the Institute of Physics at Münster University has developed a miniature abacus on a microchip which calculates using light signals. With it they are paving the way to the development of new types of computer in which, as in the human brain, the computing and storage functions are combined in one element.

Researchers at the universities of Münster, Exeter and Oxford have developed a miniature “abacus” which can be used for calculating with light signals. With it...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

 
Latest News

Need entangled atoms? Get 'Em FAST! with NIST's new patent-pending method

08.11.2017 | Physics and Astronomy

New approach uses light instead of robots to assemble electronic components

08.11.2017 | Information Technology

Tracking down the origins of gold

08.11.2017 | Awards Funding

VideoLinks
B2B-VideoLinks
More VideoLinks >>>