No abstract

In-situ burning (ISB) is one of the most effective means of removing oil spilled over open water. While current ISB practices can eliminate a large fraction of the spilled oil, they still result in significant airborne emissions of particulate matter. ISBs are classified as large, free-buoyant pool fires, from which black smoke consisting of particulate matter (PM, soot) emanates as a plume. An experimental investigation of soot emissions from pool fires (PF) and fire whirls (FW) was conducted using liquid hydrocarbon fuels, nheptane and Alaska North Slope (ANS) crude oil, in fuel pools 10 − 70 cm in diameter. Burning attributes such as burning rate, fuel-consumption efficiency, and emissions of PM, unburned hydrocarbons, carbon dioxide, and oxygen consumption were measured. For both fuels and all pool diameters, compared to PFs, FWs consumed fuel at a higher rate, had lower post-combustion residual mass and PM emission rates. Collectively, these resulted in consistently lower PM emission factors (EF PM ) for FWs at all scales. For FWs, EF PM decreased linearly with a nondimensional quantity defined as the ratio of inverse Rossby number to nondimensional heat-release rate. These results show that the addition of ambient circulation to free-burning PFs to form FWs can increase burning efficiency, reducing both burning duration and EF PM across length scales. The reduction in EF PM with increasing influence of circulation is attributed to a feedback loop of higher temperatures, heat feedback, burning rate and air-entrainment velocity, which in turn contributes to maintaining the structure of a FW. Boilover was observed for fires formed with ANS crude oil at the 70 cm scale, although the overall EF PM was not affected significantly. This investigation presents a foundation to evaluate the detailed mechanisms further, such that appropriate configurations can be developed help minimize the environmental impact of ISBs.

Recent explosions with devastating consequences have re-emphasized the relevance of fire safety and explosion research. From earlier works, the severity of the explosion has been said to depend on various factors such as the ignition location, type of a combustible mixture, enclosure configuration, and equivalence ratio. Explosion venting has been proposed as a safety measure in curbing explosion impact, and the design of safety vent requires a deep understanding of the explosion phenomenon. To address this, the Explosion Venting Analyzer (EVA)—a mathematical model predicting the maximum overpressure and characterizing the explosion in an enclosure—has been recently developed and coded (Process Saf. Environ. Prot. 99 (2016) 167). The present work is devoted to methane explosions because the natural gas—a common fossil fuel used for various domestic, commercial, and industrial purposes—has methane as its major constituent. Specifically, the dynamics of methane-air explosion in vented cylindrical enclosures is scrutinized, computationally and experimentally, such that the accuracy of the EVA predictions is validated by the experiments, with the Cantera package integrated into the EVA to identify the flame speeds. The EVA results for the rear-ignited vented methane-air explosion show good agreement with the experimental results.

I would like to express my gratitude to my advisor, Prof. Ali Rangwala for his guidance, patience, and providing all the means for doing research. It is a sincere pleasure to thank Prof. Kathy Notarianni who made the whole thing possible for me. I'm grateful that I got to conduct experiments and witness dozens of fire tests during my study. I must also thank Prof. Albert Simeoni who was able to provide me with useful insights for the most part of the project. I should also thank Dr. Lydia Shi lab manager of the Combustion Lab, Sreenivasan Ranganathan, Haoran Li, Minkyu Lee, and Andre DaVitoria who assisted me on every occasion I was in need of help with my experiments. Without question the previous work done by Peter Bellino was the best guidance I could ask. Finally, I would also like to thank my parents, elder sister, and two elder brothers. They were always supporting me and encouraging me with their best wishes even though they were thousands miles away.