Air Force Office of Scientific Research Awards $3M for Research into Graphene Additives for Novel Aviation and Diesel Fuels
21 July 2009
The US Air Force Office of Scientific Research (AFOSR) has awarded an interdisciplinary team of scientists led by Princeton engineers a two-year, $3-million grant to develop nanoscale graphene additives for novel fuels to help supersonic jets fly faster and diesel engines cleaner and more efficient.
The funding, which comes as part of the 2009 American Recovery and Reinvestment Act Research Program (funding opportunity AFOSR-BAA-2009-3), will be used to tackle a fundamental fuel barrier to designing faster supersonic aircraft.
To increase the speed of supersonic aircraft, their engines must operate at faster speeds and fuel must move through them more rapidly. However, the ignition time and burn rate of current jet fuels limits the speed of the engines.
To fly at highly supersonic speeds one needs to run the propulsion system at supersonic speed to maximize its efficiency, but there is little time to mix, ignite and extract energy from the fuel. To make the planes go faster, we need to burn fuel faster.
—Richard Yetter, a professor of mechanical engineering at Pennsylvania State University and a principal investigator on the project.
In response to the Funding Opportunity Announcement issued by AFOSR on 3 April 2009, the Princeton-led team proposed a solution based on the use of graphene—molecular sheets of carbon atoms.
In 2003, Aksay and his chemical engineering colleague, Professor Robert Prud’homme, developed the first commercially viable technique for making graphene by using a chemical process to split graphite into its ultrathin individual sheets. The resulting flakes are 200- to 500-nanometers wide.
Graphene is a one-atom thick planar sheet of carbon in a honeycomb lattice. It exhibits unusual physical and electrical properties and has been lauded for its potential in ultrafast and light electronic technologies such as computers and digital displays. Aksay and his colleagues are hoping to leverage another characteristic of the graphene particles: When small amounts are added to liquid fuels, they lower the temperature at which the fuel ignites.
The concentration of the nanocatalyst in the fuel would be very small. The idea of being able to put in a very small quantity and have such a dramatic effect is important.
...Right now we don’t know what actual reactions enhance the combustion rates when the particles are added to fuels. If we understand it further, we can make it more effective.
—Ilhan Aksay, a professor of chemical engineering at Princeton and the lead investigator on the project
The catalyst might also be used to reduce the amount of nitric oxide produced by diesel engines or accelerate soot oxidation rates, which could reduce the pollution and fuel use. The graphene particles might also be used in liquid propellants for thrusters that help satellites position themselves in space.
The team led by Aksay blends expertise in various fields. It includes several other Princeton professors: Annabella Selloni and Roberto Car of chemistry; and Frederick Dryer of mechanical and aerospace engineering. Additional researchers from other universities include: Mark Barteau of chemical engineering from the University of Delaware; Jennifer Wilcox of energy resources engineering from Stanford University; and Michael Zachariah of mechanical engineering and chemistry from the University of Maryland.
Aksay and his colleagues are also investigating self-assembled TiO2–graphene hybrid nanostructures for enhanced Li-ion insertion. A paper on that work was published earlier this year in the journal ACS nano.
Actually Fullerene (bucky balls) might have a similar effect, and they are likely to be slightly soluable in hydrocarbons. Graphene is pure carbon and it might be cheaper to produce than fullerene, but since Fullerene is a molecule, it is guaranteed to be a nano particle. On the other hand it might be too soluable in hydrocarbons. Acetylene or diacetylene would also be candidates for accelerants. A small feed of pure hot oxygen could also work. What could also work is a radical design of combustion turbines. Many, if not all turbines, pass a great deal of excess air through the machinery because combustion with the minimum necessary amount of air produces too high of a temperature for the materials which is why after-burners are possible in fighter aircraft and duct burners are possible in combined cycle power plants. Many engineers in the world have still the opportunity to accerate the combustion by devising the means to do combustion at higher temperatures. NOX at high altitudes may not actually be considered pollution. NOX is a fertilizer when it falls to the ground as rain. NOX is produced by lightning and other atmospheric electricity. Organizms work hard to produce NOX in the soil from nitrogen in the air. Many millions of tons of natural gas are processed every year to produce sources of NOX. It might be best for the world economy to devise engines that produce a lot of NOX and collect it and ship it to farmers. There is no doubt that NOX on a freeway in a city contributes to dangerous smog. ..HG..
Posted by: Henry Gibson | 21 July 2009 at 10:27 AM
NOx is a catalyst for the destruction of ozone.
Posted by: Engineer-Poet | 22 July 2009 at 09:34 PM