In this 13-part series of articles, The Combustion Institute recognizes the 2021 Distinguished Papers selected from among the scientific papers presented during the 38th International Symposium on Combustion. Congratulations to Hope A. Michelsen for winning the DPA in the Soot, Nanomaterials, and Large Molecules colloquium. 

In her paper, Effects of maturity and temperature on soot density and specific heatHope A. Michelsen provides new and easy-to-use parameterizations to better understand the connections between soot model developments and measurements. It is widely recognized that soot has negative effects on both human health and the environment. However, there are large gaps in our understanding of how it’s formed, how it evolves in the combustor, and its characteristics as it ages in the atmosphere. This lack of understanding leaves scientists without accurate predicative models for soot formation rates and particle properties, which, in turn, leave scientists without methods of estimating and mitigating the negative impacts of soot on health, climate change, and engine efficiency. 

Specifically, Michelsen focused on the lack of understanding of the characteristics of incipient particles in the larger lifecycle of soot, and the fact that scientists have no accurate model predictions of young soot particle thermodynamic properties. After conducting a review of hydrocarbon thermophysical research, Michelsen derived new expressions to estimate properties such as density and specific heat as functions of their hydrogen-to-carbon (H/C) ration and absorption cross section. 

The parameterizations Michelsen created estimate particle density and specific heat from inception to full maturity, opening doors to newer and more accurate predictive models for scientists in dozens of fields. Michelsen’s research advances not only the development of predictive models in soot applications, but also advances the field’s general knowledge of soot formation.   

At the heart of this paper is Michelsen’s meticulous literature review of hydrocarbon thermophysical data from the last century. In 2018, while Michelsen was on medical leave and undergoing chemotherapy, she was unable to conduct her regular research on soot diagnostics and chemistry. Uninspired by her doctor’s recommendations of crossword puzzles and sudoku to ward off “chemo-brain,” Michelsen decided to ponder questions about particle density and specific heat. The more she looked at the literature, the more interesting the topic became to her, and she ended up finding solutions in a seemingly out-of-reach area. 

Once her medical leave ended and Michelsen began her position at the University of Colorado Boulder, she was able to finish her studies and write this award-winning paper, a far cry from succumbing to “chemo-brain!” 

Over 1,700 papers were submitted to the 38th International Symposium on Combustion. All papers were categorized into one of 13 colloquia, and then distributed to colloquium coordinators and co-chairs. Each paper was reviewed by at least three qualified individuals from a pool of over 1,000 peer scientific reviewers. Less than 50 percent of the papers submitted are accepted for presentation. 

Following the symposium, one paper presented in each colloquium is awarded the distinction of Distinguished Paper. Visit here to view the presentation. The 13 Distinguished Papers undergo committee review for consideration for the Silver Combustion MedalA paper selected for this honor exemplifies quality, achievement, and significance to advance a field of combustion science, and will be awarded during the 39th International Symposium in Vancouver, Canada.