Preparation Of Nanofluids And Their Study On CO 2 Absorption Enhancement

The concept of nanofluid is proposed by Choi in the United States in 1995,which is the two-phase suspension composed of nanoparticles and base fluid,and thus promoted the development of the nano techno logy in the application of heat and mass transfer.The purpose of this paper is to investigate the stability and the enhancement of nanofluids to CO2 absorption.A comparison for nano-particles with metal,metal oxide and nonmetal oxide was made.The experimental researches of the nanofluids on the C02 mass transfer enhancement were carried out.A two-step method was employed to prepare the Cu-H2O,CuO-H2O and SiO2-H2O nanofluids.All kinds of methods,such as the visual observation,UV and the Transmission Electron Microscope(TEM)were used to observe the suspension stability of the nanofluids.From the experimental results,an optimum preparation condition was obtained.An absorption experiment was set up to investigate the enhancement of nano fluids to CO2 absorption.With the observed pressure different between the absorption reactor and the reference tank,the effects of several nano fluids on the absorption process under different operating conditions were studied.From the experimental result,the stirring speed,surfactant and ultrasonic time have a great influence on the absorption enhancement,and the three nanofluids have similar law,that is,with the increase of the mass fraction of nanoparticles and the ultrasonic time,the enhancement factor increases firstly and then decreases;with the increase of mass fraction of surfactant,a first increase and then decrease of the enhancement factor was observed,an optimum value existed;with the increase of stirring speed,the enhancement factor increases rapidly,but after a certain value of stirring speed,the enhancement factor no longer increases,but shows a downward trend.For all the three nanofluids(Cu-H2O,CuO-H2O and SiO2-H2O),the absorption enhancement factor E reaches the maximum value at mass fraction of 0.05%.The optimum ultrasonic times observed are 1.5h,45min and 60min for Cu-H2O,CuO-H2O and SiO2-H2O nano fluid respectively.When the mass fraction of SDBS added in Cu-H2O nano fluid was 0.01%and in CuO-H2O was 0.005%,the absorption enhancement factor E reached the maximum;Using Triton X-100 and SDBS as the dispersant in SiO2-H2O nano fluid,it was found that the best content for Triton is 0.005%,for SDBS is 0.01%.When the stirring rate was 60r/min,the absorption enhancement factor E reaches an optimum value for all the three nano fluids.