@article{li_ogunkoya_fang_willoughby_rojas_2016, title={Carboxymethylated lignins with low surface tension toward low viscosity and highly stable emulsions of crude bitumen and refined oils}, volume={482}, ISSN={["1095-7103"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84979781362&partnerID=MN8TOARS}, DOI={10.1016/j.jcis.2016.07.063}, abstractNote={Kraft and organosolv lignins were subjected to carboxymethylation to produce fractions that were soluble in water, displayed a minimum surface tension as low as 34mN/m (25°C) and a critical aggregation concentration of ∼1.5wt%. The carboxymethylated lignins (CML), which were characterized in terms of their degree of substitution ((31)P NMR), elemental composition, and molecular weight (GPC), were found suitable in the formulation of emulsions with bitumens of ultra-high viscosity, such as those from the Canadian oil sands. Remarkably, the interfacial features of the CML enabled fuel emulsions that were synthesized in a very broad range of internal phase content (30-70%). Cryo-replica transmission electron microscopy, which was used here the first time to assess the morphology of the lignin-based emulsions, revealed the droplets of the emulsion stabilized with the modified lignin. The observed drop size (diameters<2μm) was confirmed by light scattering, which revealed a normal size distribution. Such characteristics led to stable emulsified systems that are amenable for a wide range of applications. Emulsification with CML afforded bitumen emulsions with very high colloidal stability (no change was noted for over one month) and with a strong shear thinning behavior. Both features indicate excellent prospects for storage, transport and spraying, which are relevant in operations for power generation, which also take advantage of the high heating value of the emulsion components. The ability of CML to stabilize emulsions and to contribute in their combustion was tested with light fuels (kerosene, diesel, and jet fuel) after formulation of high internal phase systems (70% oil) that enabled operation of a fuel engine. A significant finding is that under certain conditions and compared to the respective pure fuel, combustion of the O/W emulsions stabilized by CML presented lower NOx and CO emissions and maintained a relatively high combustion efficiency. The results highlight the possibilities in high volume application for lignin biomacromolecules.}, journal={JOURNAL OF COLLOID AND INTERFACE SCIENCE}, author={Li, Shuai and Ogunkoya, Dolanimi and Fang, Tiegang and Willoughby, Julie and Rojas, Orlando J.}, year={2016}, month={Nov}, pages={27–38} }
 @article{ogunkoya_fang_2015, title={Engine performance, combustion, and emissions study of biomass to liquid fuel in a compression-ignition engine}, volume={95}, ISSN={["1879-2227"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84923774817&partnerID=MN8TOARS}, DOI={10.1016/j.enconman.2015.02.041}, abstractNote={In this work, the effects of diesel, biodiesel and biomass to liquid (BTL) fuels are investigated in a single-cylinder diesel engine at a fixed speed (2000 rpm) and three engine loads corresponding to 0 bar, 1.26 bar and 3.77 bar brake mean effective pressure (BMEP). The engine performance, in-cylinder combustion, and exhaust emissions were measured. Results show an increase in indicated work for BTL and biodiesel at 1.26 bar and 3.77 bar BMEP when compared to diesel but a decrease at 0 bar. Lower mechanical efficiency was observed for BTL and biodiesel at 1.26 bar BMEP but all three fuels had roughly the same mechanical efficiency at 3.77 bar BMEP. BTL was found to have the lowest brake specific fuel consumption (BSFC) and the highest brake thermal efficiency (BTE) among the three fuels tested. Combustion profiles for the three fuels were observed to vary depending on the engine load. Biodiesel was seen to have the shortest ignition delay among the three fuels regardless of engine loads. Diesel had the longest ignition delay at 0 bar and 3.77 bar BMEP but had the same ignition delay as BTL at 1.26 bar BMEP. At 1.26 bar and 3.77 bar BMEP, BTL had the lowest HC emissions but highest HC emissions at no load conditions when compared to biodiesel and diesel. When compared to diesel and biodiesel BTL had lower CO and CO2 emissions. At 0 bar and 1.26 bar BMEP, BTL had higher NOx emissions than diesel fuel but lower NOx than biodiesel at no load conditions. At the highest engine load tested, NOx emissions were observed to be highest for diesel fuel but lowest for BTL. At 1.26 bar BMEP, diesel had a higher smoke opacity than BTL and biodiesel. At 3.77 bar BMEP, BTL had the highest smoke opacity with diesel fuel having the lowest opacity. This work also demonstrated the effectiveness of BTL as a renewable alternative fuel with characteristics comparable to regular diesel fuel.}, journal={ENERGY CONVERSION AND MANAGEMENT}, author={Ogunkoya, Dolanimi and Fang, Tiegang}, year={2015}, month={May}, pages={342–351} }
 @article{ogunkoya_li_rojas_fang_2015, title={Performance, combustion, and emissions in a diesel engine operated with fuel-in-water emulsions based on lignin}, volume={154}, ISSN={["1872-9118"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84930675094&partnerID=MN8TOARS}, DOI={10.1016/j.apenergy.2015.05.036}, abstractNote={We report for the first time on the use of water-continuous emulsions stabilized by a bio-based macromolecule in a compression-ignition diesel engine and compare their performance, combustion and emissions against the base fuels (diesel, biodiesel, and jet fuel). For this purpose, high internal phase ratio emulsions (70:30 fuel-to-water) were produced by mechanical emulsification using carboxymethylated wood lignin as stabilizer. Combusting experiments were performed with the engine operating at 2000 rpm under three loads (0, 1.26 and 3.26 bar brake mean effective pressure, BMEP). Engine performance, in-cylinder combustion, and exhaust emissions were monitored and compared for the fuels tested. At no load condition and when compared to the respective base (single phase) fuels, an increase in the indicated work was observed for diesel and biodiesel emulsions. Compared to the base fuels, the emulsions resulted in higher engine mechanical efficiency at 1.26 and 3.26 bar BMEP except for jet fuel emulsion at 1.26 bar. Additionally, they displayed a lower brake specific fuel consumption (BSFC), if calculated on the basis of effective fuel content discounting emulsion water, and higher brake thermal efficiency. Compared to the base fuel, the respective emulsions generally presented lower peak in-cylinder pressure, lower heat release rates, and longer ignition delays at 1.26 bar and 3.26 bar BMEP; the opposite effect was observed at no-load conditions. Remarkably, a large reduction of nitrogen oxides (NOx) emissions was noted in the combustion of the fuel emulsions, which was accompanied with a relatively higher carbon monoxide (CO) release at 1.26 and 3.26 bar (at 0 bar BMEP, the emulsions produced less CO emissions). The effect of emulsions on hydrocarbon emissions and smoke opacity depended on the fuel type and the engine load. Overall, it is concluded that while reports on fuel emulsions involve oil-continuous systems, the proposed water-continuous alternative represents an opportunity for diesel engines, whereby the fuel is dispersed as micrometric droplets for improved combustion and reduced emissions. At the same time, the fuel emulsion formulation takes advantage of the surface activity and high calorific value of widely available, inexpensive lignin stabilizers, making the proposed system a viable option towards cleaner or fully bio-based fuels.}, journal={APPLIED ENERGY}, author={Ogunkoya, Dolanimi and Li, Shuai and Rojas, Orlando J. and Fang, Tiegang}, year={2015}, month={Sep}, pages={851–861} }
 @article{ogunkoya_roberts_fang_thapaliya_2015, title={Investigation of the effects of renewable diesel fuels on engine performance, combustion, and emissions}, volume={140}, ISSN={["1873-7153"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84908577588&partnerID=MN8TOARS}, DOI={10.1016/j.fuel.2014.09.061}, abstractNote={A study was undertaken to investigate renewable fuels in a compression-ignition internal combustion engine. The focus of this study was the effect of newly developed renewable fuels on engine performance, combustion, and emissions. Eight fuels were investigated, and they include diesel, jet fuel, a traditional biodiesel (fatty acid methyl ester: FAME), and five next generation biofuels. These five fuels were derived using a two-step process: hydrolysis of the oil into fatty acids (if necessary) and then a thermo-catalytic process to remove the oxygen via a decarboxylation reaction. The fuels included a fed batch deoxygenation of canola derived fatty acids (DCFA), a fed batch deoxygenation of canola derived fatty acids with varying amounts of H2 used during the deoxygenation process (DCFAH), a continuous deoxygenation of canola derived fatty acids (CDCFA), fed batch deoxygenation of lauric acid (DLA), and a third reaction to isomerize the products of the deoxygenated canola derived fatty acid alkanes (IPCF). Diesel, jet fuel, and biodiesel (FAME) have been used as benchmarks for comparing with the newer renewable fuels. The results of the experiments show slightly lower mechanical efficiency but better brake specific fuel consumption for the new renewable fuels. Results from combustion show shorter ignition delays for most of the renewable (deoxygenated) fuels with the exception of fed batch deoxygenation of lauric acid. Combustion results also show lower peak in-cylinder pressures, reduced rate of increase in cylinder pressure, and lower heat release rates for the renewable fuels. Emission results show an increase in hydrocarbon emissions for renewable deoxygenated fuels, but a general decrease in all other emissions including NOx, greenhouse gases, and soot. Results also demonstrate that isomers of the alkanes resulting from the deoxygenation of the canola derived fatty acids could be a potential replacement to conventional fossil diesel and biodiesel based on the experiments in this work.}, journal={FUEL}, author={Ogunkoya, Dolanimi and Roberts, William L. and Fang, Tiegang and Thapaliya, Nirajan}, year={2015}, month={Jan}, pages={541–554} }