Plenary Lecturers

Biography: 

Carlos Fernández-Pello is Distinguished Professor of the Graduate School at the Department of Mechanical Engineering at the University of California, Berkeley. He specializes in combustion with emphasis in fire science; he has interests across solid material flammability, wildfires, smolder combustion, droplet combustion and micro-scale power generation, . He has conducted pioneering work across many fundamental areas of combustion and fire, and his work is, and was, funded by several US government agencies including NASA, DOE, DOD, NIST, CARB. He is a Dr. Aeronautical Engineering degree from the University of Madrid, Spain, and a Ph. D from the University of California, San Diego. After being a postdoctoral fellow at Harvard University and  at Princeton University, he joined the University of California Berkeley in 1980 where he teaches in the Department of Mechanical Engineering. He also was Associate Dean of the University Wide Graduate Division, and Maynard Chair Professor in Mechanical Engineering. He has received multiple awards including the “Alfred Egerton Gold Medal” of the Combustion Institute, the “Howard Emmons Award” from the International Society of Fire Safety Science; the “Microgravity and Space Processes Award” from the AIAA; the “Philip Thomas Medal” of Excellence from the International Symposium of Fire Safety Science. He is a Fellow of the Combustion Institute and of the American Society of Mechanical Engineering. He is a Member of the Royal Academy of Engineering of Spain, a Distinguished Alumni of the University of California San Diego, and an Honorary Doctor from the University of San Carlos, Peru. He is presently on the Editorial Advisory board of the Combustion Institute, and Combustion Science and Technology. He is Co-founder of Reax Engineering, Berkeley, CA, a combustion and fire consulting company for industry and legal firms. 

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On the extinction of burning solids

Abstract:

The flammability, or fire hazard, associated with solid combustible materials, is often determined by combustion markers including ignition, flame spread, regression, heat release, extinction, and toxicity.  Although all these markers are important in different aspects of a fire, extinction is obviously critical once the solid has ignited. The determination of the extinction of a material is often based on the oxygen volume fraction below which the material doesn’t burn. Practical testing is done in the Limiting Oxygen Index apparatus (LOI- ASTM 2863), by measuring the oxygen concentration below which a material burning in a candle fashion extinguishes. The corresponding oxygen volume fraction is referred to as the limiting oxygen index, or concentration (LOI or LOC). Although significant research has been conducted on the subject, there is still a need for further 
experimentation and theoretical modeling, especially in non-earth atmospheres such as in spacecraft and space habitats. Here a summary is given of the combustion issues relevant to this problem and the current research status, emphasizing its theoretical modeling. An analytical model is proposed of the LOC of a burning solid in Space Exploration Atmospheres (SEA), i.e. reduced gravity, low velocity flow and reduced pressure. The analysis obtains two oxygen molar fraction extinction boundaries: a “heat transfer” boundary and a “chemical kinetics” boundary. The former is given by the conditions needed to heat the solid to its pyrolysis temperature, and the latter by the conditions needed for the gas phase reaction Damkholer number to equate the critical Damkholer for extinction. The combination of the two boundaries provides an overall boundary for the oxygen mole fraction for extinction as a function of material and environment properties. The model predictions are compared with data available in the literature and the results discussed.