The University of British Columbia

RESEARCH INTERESTS

Fluidization and Multiphase Reactors: Fluidized bed reactors have been widely used in industrial processes for conducting both catalytic and non-catalytic reactions, fuel combustion, particulate drying, powder coating and granulation, electrolysis etc. I started my research career on fluidization in 1985, and have conducted research over many areas of fluidization research, including hydrodynamics, flow patterns and flow regimes, heat transfer, mass transfer, reactor performance testing, modeling and simulation, scaling and scale-up, commercial reactor trouble-shooting etc. covering gas-solids, liquid-solids, gas-liquid-solids bubbling, turbulent and circulating fluidized beds. Recently we have also been working on conical spouted beds and downer reactors. My current fluidization research is focused on electrostatic charging in gas-solids fluidized beds with dielectric materials, multiscale reactor modeling and analysis, high-density circulating fluidized beds, turbulent fluidized beds, and novel fluidized bed catalytic reactors for air pollutant control.

Electrostatics: Electrostatic charges generated during particle handling, transport, and processing due to particle-particle contact and gas-particle and particle-wall frictions by frictional charging, tribo-electrification and contact charging can cause harmful electrostatic phenomena. Electrostatic adhesion due to highly charged particles can cause the formation of undesired polymer chunks in polymerization reactors, or the formation of polymer sheets on the reactor wall, leading to the generation of waste/byproduct. Electrostatic charges can also cause electrical interferences to internal sensors and thus disrupt process instrumentation. Electrostatic discharge can result in harmful electrical shocks to operating personnel and, in the worst case, can result fires or explosions in commercial power-handling equipment and manufacturing facilities. While there is an understanding of charge generation from particle-to-gas friction and particle-wall-collision, charge generation from the contact between insulating particles is still poorly understood. Local charge generation and distribution in fluidized beds, the role of bubble motion in enhancing charge generation and the resulting charge distribution around rising bubbles have not been studied until recently.

Since 1997, we have been developing experimental techniques for characterizing electrostatic charges in gas-solids fluidized beds with polymeric particles in order to reduce the charge generation and charge buildup in gas-solids fluidized bed reactors in collaboration with Nova Chemicals Inc., Mitsubishi Chemicals Inc. and Japan Polychem. So far we have, for the first time, developed a model to interpret the charge induction and transfer from the fluidized bed to an immersed ball probe based on both charge induction from passing bubbles and charge transfer due to particle-probe collisions. The model simulation has been primarily validated using data collected from cold model fluidized bed data. Since 2002, we have been studying the charge distribution around gas bubbles using image reconstruction method, and charge generation mechanisms using an in-line Faraday cup fluidized bed, with the support of a NSERC Strategic grant. So far we have made significant progress on this field, with one patent application in preparation on a novel charge monitoring technique and 8 papers published. Currently we continue our work on fundamental understanding of electrostatic charges, and also planning to apply the knowledge we have gained to help the industry to solve static charge problems in commercial gas-phase polymerization reactors and other particulate processing and handling processes.

Green Engineering, Clean Energy and Sustainability: Green engineering is the design, commercialization and use of processes and products, which are feasible and economical while minimizing impacts on ecosystems over the full life-cycle. In contrary to traditional engineering approaches in which both technical and economical aspects of a technology are the focal point, green engineering extends our research and development beyond the manufacturing of the material and product to include the ecological impacts of a process/product or a technology on the renewability and sustainability of the raw materials, the toxicity and health risks during the product use, and the recycleability and degradability at the end of the product use. In recent years, I have developed strong interest on the green engineering, a multidisciplinary multiscale approach toward sustainable development. We have been developing environmental systems analysis and life cycle analysis tools to model and evaluate the biomass collection and processing process, as well as conducted experimental studies on the fluidized bed biomass combustion to minimize the dioxin/furan formation from biomass combustion by system optimization. Collaborating with Ballard Power Systems, we have been applying our two-phase flow expertise to the water management in PEM fuel cells. So far we have made a few presentations at both national and international conferences and invited seminars on the concepts of multiscale approaches, clean and renewable energy development, fuel cells and prevention of air pollution and agricultural waste management. Meanwhile, we have been incorporating green engineering principles into the teaching, with the first green engineering course (CHBE484) introduced in 2004 at UBC. Currently, we work on PEM fuel cells, biomass processing, life cycle analysis and industrial ecology for pollution prevention and waste management. Both clean energy and green engineering will be a key area of our research and teaching in the near future.

RECENT SELECTED PUBLICATIONS

• Cannayen, I., S.J Tumuluru, S. Sokhansanj, X.T. Bi, J.C. Lim, S. Melin, E. Mohammad, A simple and inexpensive method of wood pellets macro-porosity measurement. Bioresource Technol., 101, 6528-6537, 2010.
• Yazdanpanah, F., S. Sokhansanja, A. K. Lau, C.J. Lim, X.T. Bi, S. Melin, M. Afzal, Permeability of wood pellets in the presence of fines. Bioresource Technol., 101, 5565-5570, 2010.
• Zhang, X.P. and X.T. Bi, Application of wave propagation theory to adsorption breakthrough studies of toluene on activated carbon fibre beds. Carbon, 8, 2317-2326, 2010.
• Ding Yulong, Xiaotao Bi and David Wilkinson, 3-D Numerical Simulation of Water Droplet Emerging from a Gas Diffusion Layer Surface in Micro-channels, J. Power Sources, 195, 7278–7288, 2010.
• Anderson, R, D.  Wilkinson, X.T. Bi and L.F. Zhang, Two-Phase Flow Pressure Drop Hysteresis in Parallel Channels of a PEM Fuel Cell, J. Power Sources,195, 4168-4176, 2010.
• Ryan Anderson, Lifeng Zhang, Yulong Ding, Mauricio Blanco, Xiaotao Bi, David P.Wilkinson, A Critical Review of Gas-liquid Two-phase Flow in Gas Flow Channels of PEM Fuel Fells, J. of Power Sources, 195, 4531-4551, 2010.
• Zhang, L.F., X.T. Bi, D.P. Wilkinson, J. Stumper and H.J. Wang, Gas flow rate distributions in parallel minichannels for polymer electrolyte membrane fuel cells: Experiments and theoretical analysis. J. Power Sources, 195, 3231-3239, 2010.
• Masnadi, M.S., J.R. Grace, S. Elyasi, X.T. Bi, Distribution of Multi-Phase Gas-Solid Flow across Identical Parallel Cyclones: Modeling and Experimental Study, Separation and Purification Technology, 72, 48-55, 2010.
• Yau Cyrus, P. Sauriol, Jurgen Stumper and Xiaotao Bi, Experimental determination of water transport in polymer electrolyte membrane fuel cells, J. Electrochemical Society, 157, B1310-B1320, 2010.
• Masnadi, M. S., John R. Grace, Xiaotao Bi, S. Elyasi, Gas-solid flow distribution through identical vertical passages: Modeling and stability analysis, AIChE J., 56, 2039–2051, 2010. 
• Li, T.W., Y.M. Zhang, J.R. Grace and H.T. Bi, Numerical investigation of gas mixing in gas-solid fluidized beds, AIChE J., 56, 2280-2296, 2010.
• Zhang, Y.M. X.T. Bi* and J.R. Grace, Comparison of Decoupling Methods for Analyzing Pressure Fluctuations in Gas-Fluidized Beds. AIChE J., 56, 869-877, 2010.
• Bi, H.T. and X.H. Liu, “High density and high solids flux CFB risers for steam gasification of biomass” Fuel Processing Technologies, 91, 915-920, 2010.
• Du, W., Lifeng Zhang, Xiaotao T. Bi, David P. Wilkinson, Jürgen Stumper, Haijiang Wang, Simulation of gas-liquid two-phase flow in mini-channels with liquid side introduction, I&EC, 49, 6709–6721, 2010.
• Wang, Z.G., H.T. Bi and C.J. Lim, Use of a Pressure Source Term for the Simulation of Spouted Beds, I&EC, 49, 5053-5060, 2010.
• Zhang Xiaoping and Xiaotao Bi, Study on void Behaviour in a Turbulent Fluidized Bed with FCC Powders. I & EC, 49, 6862–6869, 2010.
• Liu, M.X., Y.M. Zhang, X.T. Bi and J.R. Grace, Y.D. Zhu. Bubble size estimation by pressure fluctuations and optical fiber probes. Chem. Eng. Sci., 65, 3485-3493, 2010.
• Pa, A. and X.T. Bi, Modeling of offgas emissions for wood pellets during ocean transportation, Annal Occupational Hygiene, 54, 833-841, 2010.
• Li, T.W., J.R. Grace and X.T. Bi, Study of wall boundary condition in numerical simulations of 2D bubbling fluidized beds, Powder Technol., 203, 447-457, 2010.
• Ryan Anderson, Xiaotao Bi and David Wilkinson, Two-Phase Flow Pressure Drop Hysteresis Under Realistic Operating Conditions for a Proton Exchange Membrane Fuel Cell. Transaction of Electrochemical Society, 28, 127-137, 2010.
• Zhou, D., X. T. Bi, S. Dong, Contribution of Hydrodynamic Characteristics on the Performance of an Aerobic Biofilm Conical Fluidized Bed. Water Science and Technology, in press, 2011.
• Liu, Z.L., X.T. Bi and J.R. Grace, “Electrostatic charging behaviour of dielectric particles in a pressurized gas-solid fluidized bed,” J. of Electrostatics, 68, 321-327, 2010.
• Choi, Kwang Seok, Muammar Omar, Xiaotao Bi and John R. Grace, Experimental Study on Electrostatic Charging of Polymer Powders in Mixing Processes. J. Loss Prevention in Process Industries, 23, 594-510, 2010.
• Bi, X.T., P. Sauriol and J. Stumper, Two-phase flow distributors for fuel cell flow channels, Particuology: Science and Technology, 8, 582-587, 2010
• Hsieh, Tar-Hua, Ko-Shan Ho, Ching-Hung Huang, Xiaotao Bi, Yen-Zen Wang, Yu-Kai Han, Zhi-Long Chen, Yu-Chen Chang, "Effects of [SDS]/[H2O] Molar Ratio on the Electromagnetic Properties of Polyaniline/ maghemite Nanocomposites", Synthetic Metals, 160, 1609-1616, 2010.
• Peng, J.H., H.T. Bi, S. Sokhansanj, C.J. Lim and S. Melin, An Economical and Market Analysis of Canadian Wood Pellets. Int. J. Green Energy, 7, 128-142, 2010.
• Stephen, J., Shahab Sokhansanj, Xiatao Bi, Taraneh Sowlati, Mark Stumborg, Lawrence Townley-Smith, Trevor Kloeck., The Impact of Biomass Feedstock Supply Variability on the Delivered Price to a Biorefinery in the Peace River Region of Alberta, Canada. Biosystems Eng., 105, 298-305, 2010.
• Dong, S.S., D.D. Zhou and H.T. Bi, “Liquid-phase heterogeneous photocatalytic ozonation of phenol in liquid-solid fluidized bed: simplified kinetics modeling,” Particuology: Science and Technology, 8, 60-66, 2010.
• Stephen, J., Shahab Sokhansanj, Xiaotao Bi, Taraneh Sowlati, Mark Stumborg, Lawrence Townley-Smith, Trevor Kloeck., Analysis of Biomass Feedstock Availability and Variability for the Peace River Region of Alberta, Canada. Biosystems Eng., 105, 103-111, 2010.
• Du, W., L.F. Zhang, H.T. Bi, D. P. Wilkinson, J. Stumper1 and H.J. Wang, “Simulation of gas-liquid two-phase flow in horizontal square PEM fuel cell flow field mini-channels,” Int. J. Chem. React. Eng., 8, A15, 2010.
• Yang, T.X. and H.T. Bi “A novel internal circulating bed reactor for HC-SCR of NOx,” Environmental Science and Technology, 43, 5049-5053, 2009.
• Zhang, L.F., H.T. Bi, D. Wilkinson, J. Stumper and H.J. Wang, “Gas-liquid two-phase flow distributions in parallel channels for fuel cells,” J. Power Sources, 189, 1023–1031, 2009.
• Magelli, F., K. Boucher, H.T. Bi, S. Melin and A. Bonoli, An environmental impact assessment of exported wood pellets from Canada to Europe, Biomass & Bioenergy, 33, 434-441, 2009.
• Hsieh, Tar-Hwa, Ko-Shan Ho, Xiaotao Bi, Yu-Kai Han, Zhi-Long Chen, Chia-Hao Hsu, Yu-Chen Chang. Preparation and Electromagnetic Properties of Polyaniline -Coated Silica/Maghemite Nanoparticles. European Polymer Journal, 45, 613-620, 2009.
• Zhang, Y.M., C.X. Lu, J.R. Grace and H.T. Bi, Effect of louver baffles on hydrodynamics and gas mixing in a fluidized bed of FCC particles. Chem. Eng. Sci., 64, 3270-3281, 2009.
• Moughrabiah, W., J.R. Grace and X.T. Bi, “Effect of pressure and temperature on electrostatics in fluid beds of PE particles,” Ind. & Eng. Chem., 48, 320-325, 2009.
• Chen, Z.Q., H.T. Bi and J.R. Grace, Electrostatics generation in a small cyclone separator, Ind. & Eng. Chem., 185-190, 2009.
• Zhou, D.D., H.L Wang, S.S. Dong and H.T. Bi, “Characteristics of tapered three-phase fluidized beds”, Ind. & Eng. Chem., 48, 27-36, 2009.
• Grace, J.R., H.T. Bi and Y.M. Zhang, “Pitfalls in Gas Sampling from Fluidized Beds,” Chem. Eng. Sci., 64, 2522-2524, 2009.
• Kuang, X.Y, T. Jaya Shankar, X.T. Bi, C.J. Lim, S. Sokhansanj*, S. Melin, Rate and peak concentrations of emissions in stored wood pellets - sensitivities to temperature, relative humidity, and headspace volume,” Ann. Occupational Hygiene, 53, 789 - 796, 2009.
• Kuang, Xingya, Tumuluru Jaya Shankar, Shahab Sokhansanj, C. Jim Lim, Xiaotao T. Bi, Staffan Melin. Effects of headspace and Oxygen Level on the Off-gas Emission from Stored Wood Pellets. Ann. Occupational Hygiene, 53, 807 - 813, 2009.
• Igathinathane C., S. Melin, S. Sokhansanj, X. Bi, C. J. Lim, L. O. Pordesimo, E. P. Columbus, Machine vision based particle size and size distribution determination of airborne dust particles of wood and bark pellets, Powder Technology, 196, 202-212, 2009.
• Wang, Z.G., H.T. Bi and C.J. Lim, Measurement of Local flow structure in spouted beds, Can. J. Chem. Eng., 87, 264 - 273, 2009.
• Du, W., H.T Bi, N. Epstein, Exploring a non-dimensional varying exponent equation relating minimum spouting velocity to maximum spoutable bed depth, Can. J. Chem. Eng., 87, 157-162, 2009.
• Xu, J., X.J. Bao, W.S. Wei, H.T. Bi, J.R. Grace and C.J. Lim, Chaotic characteristics of pressure fluctuations in a gas spouted bed, Can. J. Chem. Eng., 87, 252-263, 2009.
• Hsieh, Tar-Hwa, Jan-Kuan Huang, Ko-Shan Ho, Xiaotao Bi, Yu-Kai Han, Shin-Shiao Yang, Yu-Chen Chang. Preparation, Thermal and Thermo-oxidative Stability of Vinylidene Chloride -co- Vinyl Chloride Copolymer /synthetic Hectorite Nanocomposites. J. of Applied Polymer Science, 113, 3171–3180, 2009.
• Yang, Shin-Shiao, Tar-Hwa Hsieh, Xiaotao Bi, Ko-Shan Ho, Tsung-Han Ho, Ho-Ruei Chen, Shi-Hao Ye, Yu-Chen Chang, Dynamic Cure Kinetics of Epoxy-Novolac Compounds by Differential Scanning Calorimetry. J. Applied Polymer Science, 114, 2373-2377, 2009.
• Dong SS, Zhou DD, Bi XT, Gao X., “Start-up and biofilm formation in an aerobic conical fluidized-bed biofilm reactor”, Environmental Science (Chinese), 30(3), 827-833, 2009.
• Chau, J., T. Sowlati, S.  Sokhansanj, F.  Preto, S. Melin, X. Bi “Economic sensitivity of wood biomass utilization for greenhouse heating application,” Applied Energy, 86, 616–621, 2009.
• Chau, J., T. Sowlati, S.  Sokhansanj, F.  Preto, S. Melin, X. Bi “Techno-Economic Analysis of Wood Biomass Boilers for the Greenhouse Industry,” Applied Energy, 86, 364-371, 2009.
• Sauriol, P., D.S. Nobes, H.T. Bi, J. Stumper, D. Kiel, D. Jones, "Design and Validation of a Water Transfer Factor Measurement Apparatus for PEMFCs," Int. J.Fuel Cell Science and Technology, 6(11), 1-13, 2009

OTHER AFFILIATIONS/MEMBERSHIPS

• Manager, Fluidization Research Centre (FRC)
• Member, Clean Energy Research Centre (CERC)
• Member, Biomass and Bioenergy Research Group (BBRG)
• Member, UBC Bridge Program
• Associate Director, Clean Energy Research Centre (CERC)
• Guest Professor, Department of Chemical Engineering, Tsinghua University, China
• Guest Professor, Department of Chemical Engineering, China Petroleum University

TEACHING

• CHBE 484. Green Engineering Principles and Applications for Process Industries
• CHBE 523. Energy and the Environment
• CHBE 561. Particle Technology