Hang Yu,Tieyan Li,Xingda Yang,Chunxi Li,Jianguo Mi,Hong Meng,Junsu Jin
In order to improve the heat transfer efficiency of the shaped activated carbon in CO 2 adsorption, we proposed a rapid CO 2 adsorption–desorption approach by coating the outer surface of the metal tube with a hydrophobic carbon layer. The coating layer was prepared by carboxylated cellulose nanofibers (CNF) as the binder, coconut shell-activated carbon as the carrier, and methyltrimethoxysilane (MTMS) as the hydrophobic modifier. The oxygenated groups can increase its surface polarity and adsorptivity for the weakly polar small molecules like carbon dioxide. The equilibrium adsorption capacity of SAC-6-1.0 for CO 2 in dry (15 vol% CO 2 ) and wet flue gas (15 vol% CO 2 + 4.7 vol% H 2 O) is 39.4 mg/g and 34.3 mg/g, respectively, at 40 °C and 1.0 bar, which is 54.5% and 382.4% higher than that of the original activated carbon. After 10 cycled reuses, over 97% of its adsorption capacity can be retained. The CO 2 adsorption performance of SAC-6-1.0 is better than most of the oxygenated and sulfur-doped activated carbons, albeit slightly worse than that of nitrogen-doped ones. The present hydrophobic carbon coating approach is of great industrial application in the field of CO 2 capture and other gas separation.
Due to the oil field development enters the period of high water cut, the flow drag of oil-water two-phase flow in nonmetallic pipes requires further research. Moreover the dynamic spreading behavior of oil droplet on a pipe’s wall is of great significance to investigate the flow drag. However, the spreading behaviors of oil droplets on surfaces with different wettabilities in water system are still not clear. In this study, firstly, considering the effect of surface wettability and oil droplet diameter, the spreading behaviors of oil droplets on non-metallic and metallic substrates were observed using a high-speed imaging system. Then, according to the spreading behaviors of oil droplets on the substrates and based upon the energy balance theory, a theoretical model of the spreading behavior of oil droplets was developed for predicting the dimensionless maximum spreading diameter. The quantitative relationships among the dimensionless maximum spreading diameter, the diameter of oil droplets, the properties of oil and water, and the wettabilities of surfaces were obtained. Finally, the theoretical model was verified using experimental data with deviations generally ranging within ± 10%.
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