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

Theenhancement of gas-liquid mass transfer is an important content in energy saving and emission reduction research field.In chemical engineering or petrochemical industry,particles are often dispersed into liquid to enhance gas-liquid mass transfer.In recent years,with the development of nanotechnology,nanoparticles are gradually used as the dispersed phase to strengthen gas-liquid mass transfer.At present,the related research has attracted more and more attention,but the microscopic mechanism of mass transfer enhancement remains unclear and the corresponding mathematical model is not enough to support engineering applications.Therefore,it is necessary to investigate the enhancing of gas-liquid mass transfer by nanoparticles in depth.In this paper,Zeta potentiometer was used to measure the actual size of nanoparticles in nanofluid.The study found that the actual size of nanoparticles was larger than the solid particle size as nanoparticles agglomerated.The larger the nanoparticle size was,the weaker the agglomeration trend was.In order to study the characteristics of nanofluid viscosity,viscosity test-bed was established to investigate the influences of solids loading,particle size,and temperature.The results showed that the viscosity of nanofluid increased with increasing solids loadings,decreased with increasing of particle sizes,and decreased with increasing temperature.However,the dimensionless viscosity did not change with temperature.In this paper,we established a model to analyze the relations between nanofluid viscosity and base fluid viscosity,solids loading,particle size,and temperature.The model was used to forecast the experimental results.The calculated values from the model were consistent with the experimental values,which proved the correctness of the model.In order to understandthe effect of nanoparticles on gas-liquid mass transfer,a stirred reactor was established to study the influences of solids loading and particle size on CO2 absorption by propylene carbonate.The research found that the CO2 absorption enhancement factor firstly increased and then decreased with the increases of solids loadings,suggesting the existence of optimal solids loading.When the solids loading was at low level,smaller nanoparticles resulted in larger enhancement factors.When the solids loading was at high level,larger nanoparticles basically created larger enhancement factors.In order to explore the mechanism of nanoparticles enhancing gas-liquid mass transfer,a three-dimensional instantaneous multi-particle model based on both the shuttle mechanism as well as a micro-convection mechanism was developed.The results calculated by the model were contrasted with experimental results,and proved the correctness of the model.The model would provide useful information to reveal the mechanisms of nanoparticles' enhancement to gas-liquid mass transfer.