应动力工程多相流国家重点实验室副主任白博峰教授的邀请，美国麻省理工学院Ahmed F. Ghoniem教授将于9月4日（周一）在我院进行访问交流并举办两场学术讲座，欢迎感兴趣的老师和同学参加。
Title: Multiscale CFD Simulations of Fluidization Dynamics: Bubbles, Mixing and Reactor Scaling
Abstract: Fluidized bed reactors find many applications in the energy and chemical industries, including combustion, gasification and catalytic reactors, because of their superior mixing characteristics. Experimental studies of these reactors are hampered by an environment hostile to most diagnostics, and optimal design especially for new applications is a significant engineering challenge. CFD offers a promising alternative. We will discuss recent development in approaches using the two-fluid model, offering a balance between computation efficiency and accuracy. Following a discussion of its fundamentals, we will show how critical submodels for particle-scale dynamics and their interactions with the gas and reactor walls are constructed and validated, and how computational schemes are improved achieving efficiency that allows for practical scale simulations. Results are used to examine bubble dynamics and coalescence, and their impact on solids mixing. Novel computational diagnostics are proposed and applied to discern gas flow distribution, mixing time scales and impact of design and operating conditions on fuel conversion. Results are also used to develop new scaling and reduced models. The use of discrete element methods to develop elaborate submodels is reviewed.
Title: Efficient Low-Rank Coal Gasification with ScCO2 Slurry Feed
Abstract: Coal and other solid fuels gasification is used in multiple technologies including electricity generation (IGCC), and syngas production for fuels and chemicals. High pressure entrained flow gasifiers are used extensively for this purpose, but their use is often limited to higher quality coals. Moreover, the cold gas efficiency is compromised by the fuel feeding system when coal-water slurry is used. This is a major concern especially when gasification is used in CO2 capture plants. Alternative system design and coal feeding technology can overcome both, utilizing CO2-coal slurry. In this talk we will demonstrate the gain in plant and cold gas efficiencies associated with the latter, and how this is especially important for extending gasification technology to lower quality coals. We show how multiscale analysis, including system level modeling of the plant that incorporates reduced order reactor models can be used to determine the impact of coal quality and operating conditions on the system including efficiency and oxygen use. Reduced reactor models are based on detailed CFD analysis, while incorporating microscale particle conversion and micro-kinetics derived for the gasification agent and coal rank. We will describe a novel feeding process that we call PHICCOS (phase inversion based CO2 slurry) for preparing the high-pressure slurry using supercritical CO2 and pulverized coal. Overall economics under uncertainty show significant advantages especially when using low rank feed.
Ahmed F. Ghoniem教授简介
Ahmed F. Ghoniem is the Ronald C. Crane Professor of Mechanical Engineering at MIT, and director of the Center for Energy and Propulsion Research and the Reacting Gas Dynamics Laboratory. He received his B.Sc. and M.Sc. degree from Cairo University, and Ph.D. at the University of California, Berkeley. His research covers computational engineering, clean energy with focus on CO2 capture technologies, renewable energy and alternative fuels. He made fundamental contributions to multiscale simulations, thermochemistry and combustion, energy systems and materials chemistry. He supervised more than 100 M.Sc., Ph.D. and post-doctoral students, published more than 500 refereed articles in leading journals and conferences, lectured extensively around the World, and consulted for the aerospace, automotive and energy industry. Ghoniem is Fellow of ASME and APS, and associate fellow of AIAA. He received several awards including the ASME James Harry Potter Award in Thermodynamics, the AIAA Propellant and Combustion Award, and the KAUST Investigator Award.