Experimental And Model Study Of Gas-liquid Mass Transfer Enhancement By Nanoparticles

Adding the fine particles to the liquid phase is a common method to enhance themass transfer. Many scholars have conducted the experiment and model studies for thephenomena of fine particles enhanced mass transfer, and proposed the relevantmechanisms to explain the phenomena. But their main research is for micro-particlesdue to the lack of experimental means, with the progress of experimental means,experiment and model studies of nanoparticles enhanced mass transfer are graduallyconcerned by researchers currently.In this paper, the self-designed sample cell is used for TIRF experiments based onthe total internal reflection fluorescence microscopy to study variation of nanoparticleBrownian motion with the solid loading, particle size, particle properties and base fluid.On the basis of the law of nanoparticle Brownian motion, microscopic measurements ofmass transfer experiment is designed based on TIRF to study the effect of Brownianmotion on enhancing mass transfer. Nanoparticle Brownian motioncauses the motion ofthe surrounding liquid, and the liquids between adjacent particles interfere with eachother leading to the micro-convection which causes additional mass transfer. Based onthe macro-convective mass transfer theory, the time-averaged method is used to analyzethe effect of Brownian motion on enhancing mass transfer, andSh pnumber isproposed to indicate the ratio between the micro-convective mass transfer and diffusionmass transfer. And then dimensional analysis and least-squares method are used toobtain the correlation of micro-convective mass transfer coefficient based on theexperimental data.In order to study the model of nanoparticle enhanced the gas-liquid mass transfer,the experiment of sulfite forced oxidation with nanoparticles is conducted in the stirredtank to study the effects of the solid loading, particle size, stirring speed, temperatureand particle properties on the gas-liquid mass transfer. Based on the shuttle effect andboundary mixing effect, three-dimensional unsteady heterogeneous mass transfer modelis built considering the effect of chemical reaction and model calculations andexperimental results are compared to find they are consistent basically. According to theboundary mixing effect, nanoparticle Brownian motion changes the hydrodynamic conditions and the effect of nanoparticle Brownian motion on the diffusion coefficientand residence time of liquid infinitesimal etc. can be obtained.In order to further study the effect of nanoparticles on the chemical absorption andverify the above mass transfer model, the experiments of CO2bubbling absorption bynanofluids based on the MEA/MDEA solution are conducted in the self-designedbubble absorber. The results are calculated using the above model by simplifying theexperimental conditions, and model calculations and experimental results are in goodagreement which indicates the accuracy of the model to a certain extent and it providesa theoretical reference for the studies of nanoparticles enhanced gas-liquid masstransfer.