Study Of Gas-liquid Mass Transfer Enhanced By Nanofluids

Nanofluids has special properties of higher thermal conductivity, superior stability, and uniformity. The purpose of this paper is to explain the enhancement of gas-liquid mass transfer characteristics in nanofluids by comparing the similarities and differences between heat and mass transfer mechanism.Nanofluids prepared by two-step method show good stability and evenness, which were illustrated by the methods of sedimentation and Scanning Electron Microscope(SEM). Some factors that affect the viscosity and surface tension of nanaofluids were discussed. The results show that nanofluids was Newtonian fluid in low concentration, and the volume fraction of nanoparticles was the dominating factor affecting viscosity, besides of diameter and temperature. The addition of nanoparticles has a slight effect on the surface tension of nanofulids studied in this paper, and the surface tension decreased slightly as the accretion of volume fraction of nanoparticles.An experimental system was designed and built up to investigate the mechanism wich enhance gas absorption in nanofluids. The results show that the enhancement factor of absorption ratio increase almost linearly with increasing of volume fraction of nanoparticles, and the gas holdup rise when absorption stopped. The addition of nanoparticles led to the micro convection of base fluid, which increased the diffusibility of base fluid, introduced shuttle effect, impeded the coalescence of bubbles, strengthened absorption rate of CO₂ in nanofluids.A simulator of horizontal gas-liquid interfacial mass transfer process was established. By making use of Particle Image Velocimetry (PIV), a series of quantitative measurement of the velocity distributions are made for the micro convections generated in the gas-liquid mass transfer of the system of nanaofluids-CO₂. The micro convections occur in main body of fluid, and it intensified with the volume fraction of nanoparticles. The velocity and vorticity increased largely comparing with the base fluid. Nanofluid has a higher potential to resolve gas.Finally, Lattice Boltzmann method was used to simulate nanofluids flow. The results show that the intensity of turbulence was increased significantly, which were helpful for energy and mass transfer.