Research interests + projects
Multiphase Systems and Reaction Engineering
Understanding the hydrodynamics of fluidized beds is critical to the design and scaling of fluidized bed reactors which are used as various reactors. This research deploys various measurement techniques and modeling methods to study and predict the behaviour of fluidized beds and other multiphase reactors. More recently, a novel travelling fluidized bed was taken to various institutions in North America and Europe to collect hydrodynamic data using advanced measurement techniques. Data collected (publically available) should serve as a benchmark database for validation of CFD and other models.
Chemical Looping Systems
One of the new applications of fluidized bed reactors is Chemical-Looping Combustion, CLC, which produces power by connecting two fluidized beds: a fuel reactor and an air reactor. In this configuration, air is never mixed with fuel. Instead, a metal oxide supplies the oxygen required for fuel combustion. It circulates in a loop, connecting the air reactor and fuel reactor. This novel configuration prevents NOx formation, and produces pure stream of steam and CO2, from which CO2 is separated without energy or economic penalty.
In another system, sorbent moves around the two interconnected fluidized fuel and reactor beds capturing CO2 in a gasification/carbonation cycle. Biomass gasifier with Calcium looping cycle can increase gas efficiencies and lead to negative carbon emissions.
The thermochemical process of biomass can lead to generation of heat, electricity and/or biofuels. Biomass has the potential to generate carbon-neutral energy. Current projects include biomass gasification with catalytic tar reduction; biomass pyrolysis; and utilization of pyrolysis products, bio-oil and biochar. We are working on biomass to synthetic natural gas through the BC BioAlliance RNG project. Biochar is applied as catalysts for biomass tar cracking, or adsorbent for waste water treatment.
The Biodiesel Project at UBC explores the production of alternative fuel from locally-obtained waste and non-food grade cooking oil, using an alkali-catalyzed transesterification process. The production unit is housed in CHBE 536, and has the capacity to produce 60L of biodiesel per batch. Students from Engineers for a Sustainable World are involved in producing biodiesel to supply fuel to trucks on campus. A fuel station in the CHBE courtyard dispenses a biodiesel/diesel blend.
Sustainability Leadership and Environmental Literacy
In 2013/2014, The University Sustainability Initiative (USI) identified various ways of integrating sustainability into large first-year courses at UBC. Using the concept of “campus as a living lab”, UBC has a tremendous opportunity to engage students in sustainability-related issues and advance environmental literacy in higher education.
Selected publications + presentations
Kim, J.Y., Ellis, N., Lim, C.J., Grace, J.R., “Effect of Calcination/carbonation and Oxidation/reduction on Attrition of Binary Solid Species in Sorption-enhanced Chemical Looping Reforming”, Fuel, 271, 117665 (2020).
Ebneyamini, A., Grace, J.R., Lim, C.J., Ellis, N., Elnashaie, S.S., Mahecha-Botero, A., “Simulation of Autothermal Hydrogen-Producing Limestone Calcination for Calcium Looping in Turbulent Fluidized Bed Reactors”, Chem Eng Sci, 212, 115353 (2020).
Cheng, L., Wu, Z., Zhang, Z., Guo, C., Ellis, N., Bi, X., Watkinson, A.P., Grace, J.R., “Tar Elimination from Biomass Gasification Syngas with Bauxite Residue Derived Catalysts and Gasification Char”, Applied Energy, 258, 114088 (2020).
Mohamed, B.A., Ellis, N., Kim, C.S., Bi, X., “Microwave-assisted Catalytic Biomass Pyrolysis: Effects of Catalyst Mixtures”, Applied Catalysis B: Environmental, 253 (15), 226-234 (2019).
Rahaman, M.S., Choudhury, M.R., Ramamurthy, A., Mavnic, D.S., Ellis, N., Taghipour, F., “CFD Modelling of Liquid-Solid Fluidized Beds of Polydisperse Struvite Crystals”, International Journal of Multiphase Flow, 99, 48-61 (2018).
Laesecke, J., Ellis, N., Kirchen, P., “Production, Analysis and Combustion Characterization of Biomass Fast Pyrolysis Oil – Biodiesel Blends for Use in Diesel Engines”, Fuel, 308, 346-357 (2017).
Dehkhoda, A.M., Gyenge E., Ellis N. “A Novel Method to Tailor the Porous Structure of KOH-activated Biochar and its Application in Capacitive Deionization and Energy Storage”. Biomass Bioenergy, 87, 107-121 (2016).
Ellis, N., Masnadi, M.S., Roberts, D.G., Kochanek, M.A., Ilyushechkin, A.Y., “Mineral Matter Interactions during Co-pyrolysis of Coal and Biomass and their Impact on Intrinsic Char Co-gasification Reactivity”, Chemical Engineering Journal, 279, 402-408 (2015).
Tebianian, S., Dubrawski, K., Ellis, N., Chaouki, J., Jafari, R., Cocco, R.A., Hays, R., Karri, S.B.R., Grace, J.R., “Investigation of Particle Velocity in FCC Gas-Fluidized Beds Based on Different Measurement Techniques”, Chem Eng Sci, 127, 310-322 (2015).
Knight, A., Ellis, N., Grace, J.R., Lim, C.J., “CO2 Sorbent Attrition Testing for Fluidized Bed Systems”, Powder Technology, 266, 412-423 (2014).
Saayman, J., Xu, M., Lim, C.J., Ellis, N., “Gas Leakage Between Reactors in a Dual Fluidized Bed Reactor System”, Powder Technology, 266, 196-202 (2014).
Rahaman, M.S., Mavinic, D.S., Ellis, N., “Fluidization Characteristics of Struvite Crystals Recovered from Wastewater”, Journal of Environmental Engineering and Science, 9, 137-149 (2014).
Masnadi, M.S., Habibi, R., Kopyscinski, J., Hill, J.M., Bi, X., Lim, C.J., Ellis, N., Grace, J.R., “Fuel Characterization and Co-pyrolysis Kinetics of Biomass and Fossil Fuels”, Fuel, 117, 1204-1214 (2014).
Reaume, S.J., Ellis, N., “Use of Hydroisomerization to Reduce the Cloud Point of Saturated Fatty Acids and Methyl Esters used in Biodiesel Production”, Biomass & Bioenergy, 49, 188-196 (2013).