The Effect of Various Nanofluids on Absorption Intensification of CO2/SO2 in a Single-Bubble Column

Abstract

Application of nanoparticles in aqueous base-fluids for intensification of absorption rate is an efficient method for absorption progress within the system incorporating bubble-liquid process. In this research, SO 2 and CO 2 were separately injected as single raising bubbles containing nanofluids to study the impact of nanoparticle effects on acidic gases absorption. In order to do this, comprehensive experimental studies were done. These works also tried to investigate the effect of different nanofluids such as water/Al 2 O 3 or water/Fe 2 O 3 or water/SiO 2 on the absorption rate. The results showed that the absorption of CO 2 and SO 2 in nanofluids significantly increases up to 77 percent in comparison with base fluid. It was also observed that the type of gas molecules and nanoparticles determine the mechanism of mass transfer enhancement by nanofluids. Additionally, our findings indicated that the values of mass transfer coefficient of SO 2 in water/Al 2 O 3 , water/Fe 2 O 3 and water/SiO 2 nanofluids are, respectively, 50%, 42% and 71% more than those of SO 2 in pure water (k LSO 2 −water = 1.45 × 10 −4 m/s). Moreover, the values for CO 2 in above nanofluids were, respectively, 117%, 103% and 88% more than those of CO 2 in water alone (k LCO 2 −water = 1.03 × 10 −4 m/s). Finally, this study tries to offer a new comprehensive correlation for mass transfer coefficient and absorption rate prediction.Processes 2019, 7, 393 2 of 21 of nanoparticles, leading to induce the micro-convections in nanofluids, has the most impact on mass transfer rate [14]. Ashrafmansouri et al. comprehensively studied previous research and reported an review to highlight the impacts of nanomaterials in heat and mass transfer processes [11]. They reported that much higher thorough studies are needed to disclose the impacts of main parameters including nanoparticles mean size and morphology on absorption rate by using nanofluids. They also exhibited that nanofluid reusing as well as absorption process modeling are the most important subjects for advancement of this technique. In addition, Kim et al. showed that mass transfer rate of ammonia is enhanced when a few nanoparticles are added to the basefluid. They exhibited that bubbles breaking by nanoparticles considerably enhances mass transfer through increasing interfacial area. They also reported that smaller bubbles were produced in nanofluid than in a base fluid, leading to intensification in mass transfer surface area [15].Ma et al. declared that by adding CNTs to a basefluid, the localized micro-convection occurs due to the Brownian motion of nanotubes [16]. They reported that induced convection can intensify the ammonia molecular diffusion within the nanofluid. Moreover, they concluded that the grazing effect can be considered another mechanism enhancing the efficiency of NH 3 by means of the bubble absorption process [16]. Absorption of gas molecules by means of the nanoparticle surfaces at the bubble interface and then removing the adsorbed gas components from the nanoparticles ...

Effects of Hydrophobic and Hydrophilic Graphene Nanoflakes on Methane Dissolution Rates in Water under Vapor–Liquid–Hydrate Equilibrium Conditions

“…This effect occurs when gas molecules adsorb on the surface of a nanoparticle, usually of similar hydrophobicity, and the nanoparticle transports the additional gas into the liquid bulk where it never enters the aqueous phase but stays on the particle surface. , While this would increase the mass transfer coefficient, it would also artificially increase the recorded number of moles in the aqueous phase and also the dissolution rate, based on the methodology used for this study. Recent studies have suggested an addition to the shuttle effect, called the grazing effect, where the gas nanobubbles also desorb from the nanoparticle and go into solution. − However, the mechanism in and conditions for which the latter effect could occur (i.e., for which this would be thermodynamically favorable in the current system) have yet to be sufficiently elucidated.…”

Bubble dynamics and mass transfer characteristics from an immersed orifice plate

“…Chemical absorption method was developed to quantify the mass transferred . The mass transfer process was assumed to consist of a bubble formation stage and a bubble rising stage.…”

Gas Capture Processes

“…Karamian et al [12] investigated the effect of different nanofluids, such as water/Al 2 O 3 , water/Fe 2 O 3 , or water/SiO 2 , on absorption rate. The results showed that the absorption of CO 2 and SO 2 in nanofluids significantly increased by up to 77% in comparison with the base fluid.…”