Friday, December 6, 2013
Combustion of Uncommon Alternative Fuels for Power Generation and Transportation
Jeffrey Bergthorson, Associate Professor, Mechanical Engineering, McGill University
The research program within the Alternative Fuels Laboratory (AFL) at McGill University, directed by Dr. Bergthorson, relies upon state-of-the-art laser-diagnostic and spectroscopic experimental techniques, combined with modeling and simulation, to improve our fundamental understanding of the combustion properties of a wide range of gaseous, liquid, and solid alternative fuels. The group's research on common alternative biofuels for transportation and power-generation applications will be briefly reviewed, including the effects of fuel composition on the fundamental ignition, flame and nitric-oxide-pollutant-formation properties of gaseous and liquid biofuels including biogas, syngas, alcohols, and biojet fuels. The talk will then focus on two concepts important in low-emission and renewable electrical-power generation technologies for remote communities, or for use in hybrid-electric transportation vehicles, that operate on uncommon alternative fuels. The first is the use of heat-recirculating burners to burn diluted biogas, syngas or landfill gases, which have low volumetric energy content compared to natural gas, as heat sources within external-combustion engines for remote power generation. Such heat-recirculating burners, in conjunction with high-efficiency external-combustion engines, can also be used to burn liquid fuels in a fuel-flexible combustion system with ultra-low-NOx emissions to generate clean and efficient power for advanced hybrid-electric transportation vehicles. AFL research has revealed new insights into the flame-wall thermal coupling responsible for stabilizing the flame within such heat-recirculating burners. The second concept is the use of metal powders as recyclable carriers of renewable energy as an alternative to the much-hyped, but unrealistic, hydrogen economy. Metal powders can be burned directly with air to generate heat for external-combustion heat engines, or can be reacted with water to generate heat and hydrogen on demand for use in transportation vehicles or propulsion systems. Alternatively, the metal powders can be mixed into liquid fuels to make a combustible slurry fuel for energy-carrier or propulsion applications. Research on different methods of converting the chemical energy within the metals into useful power will be discussed, with a specific focus on the fundamental combustion properties of metal particles in hydrocarbon-flame combustion products. McGill research has discovered that new models are required to understand how metal particles burn within today's propellants and explosives or tomorrow's slurry fuels for advanced propulsion systems or metal-energy-carrier combustor technologies.