Preparation Of Nanofluid And Its Absorption Enhancement Of CO₂

Nanofluids refers to solid-liquid stable system formed by adding nano-size particles into base liquid.Since the concept of nanofluids was put forward by Choi et al in 1995,the research about nanofluids has attracted a lot of attention.According to the research results,nano-fluids show good enhancement performance in thermal conductivity.Due to the similarity between heat transfer and mass transfer,the investigation about mass transfer enhancement of nanofluids attaracted lots of concern.The improvement of gas-liquid mass transfer can reduce equipment size and energy consumption.The enhancement of CO₂absorption by nanofluids provides new ideas and methods for the mitigation of global warming and worth of research.In this paper,TiO₂nanoparticles and ATO?antimony oxide?nanoparticles were selected to prepare nanofluids.Firstly,the effects of particle size and concentration,ultrasonic time,dispersant type and adding amount on the stability of nanofluids were discussed.According to the experimental results,the 5 nm TiO₂-H₂O nanofluid is very stable without adding dispersant,and the optimal ultrasonic time is 0.5h.The larger the concentration of 10 nm and 20 nm TiO₂-H₂O nano-particles,the more unstable the nanofluids.For 10 nm TiO₂nano-fluid,the optimal dispersant content is 0.05%wt,and the ultrasonic vibration for 2 h can achieve the stable suspension effect.For 20nm TiO₂-H₂O nanofluids,the optimal dispersant addition amount was 0.1%wt and the optimal ultrasonic time was 2 h.The stability of all three ATO-H₂O nano-particles decreased with the increase of particle concentration.The addition amount of dispersant CTMAB was 0.05%,and the dispersion stability reached after 2 h ultrasound.The nano-fluid was used for gas-liquid mass transfer to absorb CO₂gas,and the efficiency of CO₂absorption was compared with distilled water to calculate the absorption enhancement factor E of nano-fluid.Factors such as particle addition amount,dispersant type and concentration,ultrasonic time,stirring speed,etc.,were changed to explore the effect of nanoparticles on absorption enhancement factor E.It was found that with the mass fraction of 5 nm TiO₂-H₂O nanofluid particles 0.2%,and the ultrasonic time 2 hr,the absorption enhancement factor E can reach 1.457.When the particle mass fraction of 10 nm TiO₂particles and CTMAB dispersant was 0.2%and 0.05%respectively,the maximum absorption enhancement factor E reached 1.426under the condition of ultrasonic time of 2 hr.mass fraction of 20 nm TiO₂particles and the dispersant CTMAB of 0.1%and 0.05%respectively,the ultrasonic time 2 hr,stirring speed 200 r/min the absorption enhancement factor E was up to 1.37.For ATO-H₂O nanofluids,when the concentration of dispersant CTMAB was 0.05%,the ultrasound 2 h,and the rotational speed 200 r/min,the maximum absorption enhancement factors of 1.37,1.3 and 1.27 reached for 10 nm,30 nm and 50 nm ATO particles respectively,with each concentration of the particles 0.05%,0.15%and0.1%.