New Diagnostics Enabling Bio-Fuels in Transportation with Reduced Air Pollutant Emissions and Improved Efficiency
2011 New Investigator Award
Almost 70% of the oil consumption in the United States is from combustion engines used for transportation. Due to concerns regarding energy security, the development of oxygenated biofuels as an alternative to petroleum is an area of intense research. Unfortunately combustion of biofuels results in increased formaldehyde and NOx emissions that are of serious environmental concerns. A reduction in emissions and increase in fuel efficiency can be realized through the development of advanced engine technologies, but this requires a better understanding of the low temperature and high pressure oxidation chemistry (< 1000 K) of biofuels. Since this chemistry is dominated by the formation hydroperoxyl radicals (HO2) and hydrogen peroxide, this project is focused on the development of in-situ sensing technology to measure important radical species, like HO2, and to provide insights into the low temperature oxidation kinetics of biofuels.
Gerard Wysocki and Yiguang Ju are developing a novel in-situ sensing method to detect key species in biofuel combustion. By using mid-infrared quantum cascade laser technology, they are aiming to optimize combustion efficiency and minimize the associated emissions.
The project involves cross-disciplinary scientific efforts that include deep understanding of combustion chemistry, dynamics and diagnostics, molecular structure and interactions with electromagnetic fields, as well as expertise in the development and application of ultra-sensitive spectroscopic detection methods.
To date a prototype optical benchtop instrument for in-situ HO2 detection has been developed. The technology leverages magneto-optic properties of radical species to perform ultra-sensitive measurements. The system is based on Faraday rotation spectroscopy (FRS), and has been used to measure HO2 radicals in the exit of an atmospheric flow reactor. HO2 concentration is estimated by fitting the experimental spectra to a model that has been developed to simulate the FRS spectra using experimental and molecular parameters as inputs. The current system is capable of HO2 detection at sub-ppm levels, and to the best of our knowledge, it is the first system capable of direct and in-situ optical measurement of HO2 in combustion at high pressure. This molecule is of great importance for validating chemical kinetic models that drive development of new combustion technologies optimized for efficient and low-emission transportation using biofuels.
Within the proposed effort Wysocki and Ju have jointly developed a new course entitled “Cleaner transport fuels, combustion sensing and emission control” (ELE/MAE/CEE 428) that has been offered in the Spring semester of 2011 and will be offered every two years from now on. The course provides a broad perspective ranging from the recent development of green fuels, through active combustion control and sensing using in-situ laser spectroscopic techniques, to global environmental impacts. The course is linked to the conducted research and also covered fundamental aspects related to the physics of fuel combustion as well as to light-matter interactions in combustion diagnostics. In addition the course also provided a review of pollutant chemistry, transport, and the global standards of emission regulations.
In addition to the lectures presented in the course a laboratory exercise that will engage students and provide hands on learning is being developed. The exercise will be based on the prototype instrument for in-situ HO2 detection, and will be offered as an addition to the course during the next course offering.
- Brian Brumfield, Wenting Sun, Yinguang Ju, Gerard Wysocki, “Faraday Rotation Spectroscopy of Radicals Relevant To Combustion’, accepted to Optical Society of America annual meeting Optical Instrumentation for Energy and Environmental Applications (E2), Eindhoven, Netherlands November 2012
- Manuscript in preparation: Brian Brumfield, Wenting Sun, Yinguang Ju, Gerard Wysocki, “In Situ Measurement of HO2 from a Flow Reactor at Atmospheric Pressure” to be submitted to JACS Communications